Java : String with Examples
Last Modified : December 10, 2023 Published : February 10, 2022
String (Java SE 20 & JDK 20) API Examples.
You will find code examples on most String methods.
Summary
The String class represents character strings. All string literals in Java programs, such as "abc", are implemented as instances of this class.
final var s = "abcde";
System.out.println(s); // "abcde"
final var upper = s.toUpperCase();
System.out.println(upper); // "ABCDE"
Fields
static final Comparator<String> CASE_INSENSITIVE_ORDER
A Comparator that orders String objects as by compareToIgnoreCase.
final var list = new ArrayList<String>();
list.add("Tree");
list.add("book");
list.add("stone");
list.add("Cake");
System.out.println(list); // [Tree, book, stone, Cake]
list.sort(Comparator.naturalOrder());
System.out.println(list); // [Cake, Tree, book, stone]
list.sort(String.CASE_INSENSITIVE_ORDER);
System.out.println(list); // [book, Cake, stone, Tree]
final var list = new ArrayList<String>();
list.add("D");
list.add("c");
list.add("B");
list.add("a");
System.out.println(list); // [D, c, B, a]
list.sort(Comparator.naturalOrder());
System.out.println(list); // [B, D, a, c]
list.sort(String.CASE_INSENSITIVE_ORDER);
System.out.println(list); // [a, B, c, D]
Constructors
String ()
Initializes a newly created String object so that it represents an empty character sequence.
// Rrecommended.
final var s = "";
System.out.println(s); // ""
System.out.println(s.isEmpty()); // true
// Unrecommended.
final var s = new String();
System.out.println(s); // ""
System.out.println(s.isEmpty()); // true
String (byte[] bytes)
Constructs a new String by decoding the specified array of bytes using the default charset.
final var bytes = "abcde".getBytes();
System.out.println(Arrays.toString(bytes)); // [97, 98, 99, 100, 101]
final var s = new String(bytes);
System.out.println(s); // "abcde"
System.out.println(Charset.defaultCharset()); // UTF-8
final var sjis = "あいうえお".getBytes("Shift_JIS");
// [-126, -96, -126, -94, -126, -92, -126, -90, -126, -88]
System.out.println(Arrays.toString(sjis));
System.out.println(new String(sjis)); // "����������" <- Garbled characters
final var utf8 = "あいうえお".getBytes(StandardCharsets.UTF_8);
// [-29, -127, -126, -29, -127, -124, -29, -127, -122, -29, -127, -120, -29, -127, -118]
System.out.println(Arrays.toString(utf8));
System.out.println(new String(utf8)); // "あいうえお"
String (byte[] ascii, int hibyte)
Deprecated. This method does not properly convert bytes into characters.
Deprecated.
String (byte[] bytes, int offset, int length)
Constructs a new String by decoding the specified subarray of bytes using the default charset.
final var bytes = "abcd".getBytes();
System.out.println(Arrays.toString(bytes)); // [97, 98, 99, 100]
System.out.println(new String(bytes, 0, 0)); // ""
System.out.println(new String(bytes, 0, 1)); // "a"
System.out.println(new String(bytes, 0, 2)); // "ab"
System.out.println(new String(bytes, 0, 3)); // "abc"
System.out.println(new String(bytes, 0, 4)); // "abcd"
System.out.println(new String(bytes, 1, 3)); // "bcd"
System.out.println(new String(bytes, 2, 2)); // "cd"
System.out.println(new String(bytes, 3, 1)); // "d"
System.out.println(new String(bytes, 4, 0)); // ""
String (byte[] ascii, int hibyte, int offset, int count)
Deprecated. This method does not properly convert bytes into characters.
Deprecated.
String (byte[] bytes, int offset, int length, String charsetName)
Constructs a new String by decoding the specified subarray of bytes using the specified charset.
Please see the method below.
String (byte[] bytes, int offset, int length, Charset charset)
Constructs a new String by decoding the specified subarray of bytes using the specified charset.
Please see the method below.
String (byte[] bytes, String charsetName)
Constructs a new String by decoding the specified array of bytes using the specified charset.
final var bytes = "abcd".getBytes("UTF-8");
System.out.println(Arrays.toString(bytes)); // [97, 98, 99, 100]
System.out.println(new String(bytes, "UTF-8")); // "abcd"
final var sjis = "あいうえお".getBytes("Shift_JIS");
// [-126, -96, -126, -94, -126, -92, -126, -90, -126, -88]
System.out.println(Arrays.toString(sjis));
System.out.println(new String(sjis, "Shift_JIS")); // "あいうえお"
final var utf8 = "あいうえお".getBytes("UTF-8");
// [-29, -127, -126, -29, -127, -124, -29, -127, -122, -29, -127, -120, -29, -127, -118]
System.out.println(Arrays.toString(utf8));
System.out.println(new String(utf8, "UTF-8")); // "あいうえお"
String (byte[] bytes, Charset charset)
Constructs a new String by decoding the specified array of bytes using the specified charset.
final var bytes = "abcd".getBytes(StandardCharsets.UTF_8);
System.out.println(Arrays.toString(bytes)); // [97, 98, 99, 100]
System.out.println(new String(bytes, StandardCharsets.UTF_8)); // "abcd"
final var sjis = "あいうえお".getBytes(Charset.forName("Shift_JIS"));
// [-126, -96, -126, -94, -126, -92, -126, -90, -126, -88]
System.out.println(Arrays.toString(sjis));
System.out.println(new String(sjis, Charset.forName("Shift_JIS"))); // "あいうえお"
final var utf8 = "あいうえお".getBytes(StandardCharsets.UTF_8);
// [-29, -127, -126, -29, -127, -124, -29, -127, -122, -29, -127, -120, -29, -127, -118]
System.out.println(Arrays.toString(utf8));
System.out.println(new String(utf8, StandardCharsets.UTF_8)); // "あいうえお"
String (char[] value)
Allocates a new String so that it represents the sequence of characters currently contained in the character array argument.
final char[] value = {'a', 'b', 'c', 'd'};
System.out.println(Arrays.toString(value)); // [a, b, c, d]
final var s = new String(value);
System.out.println(s); // "abcd"
String (char[] value, int offset, int count)
Allocates a new String that contains characters from a subarray of the character array argument.
final char[] value = {'a', 'b', 'c', 'd'};
System.out.println(Arrays.toString(value)); // [a, b, c, d]
System.out.println(new String(value, 0, 0)); // ""
System.out.println(new String(value, 0, 1)); // "a"
System.out.println(new String(value, 0, 2)); // "ab"
System.out.println(new String(value, 0, 3)); // "abc"
System.out.println(new String(value, 0, 4)); // "abcd"
System.out.println(new String(value, 1, 3)); // "bcd"
System.out.println(new String(value, 2, 2)); // "cd"
System.out.println(new String(value, 3, 1)); // "d"
System.out.println(new String(value, 4, 0)); // ""
String (int[] codePoints, int offset, int count)
Allocates a new String that contains characters from a subarray of the Unicode code point array argument.
final var codePoints = "abcd".codePoints().toArray();
System.out.println(Arrays.toString(codePoints)); // [97, 98, 99, 100]
System.out.println(new String(codePoints, 0, 0)); // ""
System.out.println(new String(codePoints, 0, 1)); // "a"
System.out.println(new String(codePoints, 0, 2)); // "ab"
System.out.println(new String(codePoints, 0, 3)); // "abc"
System.out.println(new String(codePoints, 0, 4)); // "abcd"
System.out.println(new String(codePoints, 1, 3)); // "bcd"
System.out.println(new String(codePoints, 2, 2)); // "cd"
System.out.println(new String(codePoints, 3, 1)); // "d"
System.out.println(new String(codePoints, 4, 0)); // ""
String (String original)
Initializes a newly created String object so that it represents the same sequence of characters as the argument; in other words, the newly created string is a copy of the argument string.
// Rrecommended.
final var s = "abcd";
System.out.println(s); // "abcd"
// Unrecommended.
final var s = new String("abcd");
System.out.println(s); // "abcd"
String (StringBuffer buffer)
Allocates a new string that contains the sequence of characters currently contained in the string buffer argument.
final var buffer = new StringBuffer();
buffer.append("num : ");
buffer.append(123);
final var s = new String(buffer);
System.out.println(s); // "num : 123"
String (StringBuilder builder)
Allocates a new string that contains the sequence of characters currently contained in the string builder argument.
final var builder = new StringBuilder();
builder.append("num : ");
builder.append(123);
final var s = new String(builder);
System.out.println(s); // "num : 123"
Methods
char charAt (int index)
Returns the char value at the specified index.
final var s = "abc";
//s.charAt(-1); // IndexOutOfBoundsException
System.out.println(s.charAt(0)); // a
System.out.println(s.charAt(1)); // b
System.out.println(s.charAt(2)); // c
//s.charAt(3); // IndexOutOfBoundsException
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = surrogate + "ab";
System.out.println(s); // "𩸽ab"
final var ret1 = s.charAt(0);
System.out.println(ret1); // ? <- Garbled characters.
System.out.println(Integer.toHexString(ret1)); // d867
final var ret2 = s.charAt(1);
System.out.println(ret2); // ? <- Garbled characters.
System.out.println(Integer.toHexString(ret2)); // de3d
final var ret3 = s.charAt(2);
System.out.println(ret3); // a
final var ret4 = s.charAt(3);
System.out.println(ret4); // b
//s.charAt(4); // IndexOutOfBoundsException
IntStream chars ()
Returns a stream of int zero-extending the char values from this sequence.
// Unicode : 0x61 = a, 0x62 = b, 0x63 = c, 0x64 = d, 0x65 = e
final var ret = "abcde".chars();
// [61, 62, 63, 64, 65]
System.out.println(ret.mapToObj(Integer::toHexString).toList());
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = "ab" + surrogate;
System.out.println(s); // "ab𩸽"
final var ret = s.chars();
ret.forEach(c -> {
System.out.println("%x : %c".formatted(c, c));
});
// Result
// ↓
// "61 : a"
// "62 : b"
// "d867 : ?" <- Garbled characters
// "de3d : ?" <- Garbled characters
int codePointAt (int index)
Returns the character (Unicode code point) at the specified index.
final var s = "abc";
//s.codePointAt(-1); // IndexOutOfBoundsException
System.out.println("%c".formatted(s.codePointAt(0))); // a
System.out.println("%c".formatted(s.codePointAt(1))); // b
System.out.println("%c".formatted(s.codePointAt(2))); // c
//s.codePointAt(3); // IndexOutOfBoundsException
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = surrogate + "ab";
System.out.println(s); // "𩸽ab"
final var ret1 = s.codePointAt(0);
System.out.println("%c".formatted(ret1)); // 𩸽
System.out.println(Integer.toHexString(ret1)); // 29e3d
final var ret2 = s.codePointAt(1);
System.out.println("%c".formatted(ret2)); // ? <- Garbled characters.
System.out.println(Integer.toHexString(ret2)); // de3d
final var ret3 = s.codePointAt(2);
System.out.println("%c".formatted(ret3)); // a
final var ret4 = s.codePointAt(3);
System.out.println("%c".formatted(ret4)); // b
//s.codePointAt(4); // IndexOutOfBoundsException
int codePointBefore (int index)
Returns the character (Unicode code point) before the specified index.
final var s = "abc";
//s.codePointBefore(0); // IndexOutOfBoundsException
System.out.println("%c".formatted(s.codePointBefore(1))); // a
System.out.println("%c".formatted(s.codePointBefore(2))); // b
System.out.println("%c".formatted(s.codePointBefore(3))); // c
//s.codePointBefore(4); // IndexOutOfBoundsException
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = surrogate + "ab";
System.out.println(s); // "𩸽ab"
//s.codePointBefore(0); // IndexOutOfBoundsException
final var ret1 = s.codePointBefore(1);
System.out.println("%c".formatted(ret1)); // ? <- Garbled characters.
System.out.println(Integer.toHexString(ret1)); // d867
final var ret2 = s.codePointBefore(2);
System.out.println("%c".formatted(ret2)); // 𩸽
System.out.println(Integer.toHexString(ret2)); // 29e3d
final var ret3 = s.codePointBefore(3);
System.out.println("%c".formatted(ret3)); // a
final var ret4 = s.codePointBefore(4);
System.out.println("%c".formatted(ret4)); // b
//s.codePointBefore(5); // IndexOutOfBoundsException
int codePointCount (int beginIndex, int endIndex)
Returns the number of Unicode code points in the specified text range of this String.
final var s = "abc";
System.out.println(s.codePointCount(0, 3)); // 3
System.out.println(s.codePointCount(1, 2)); // 1
//s.codePointCount(-1, 3); // IndexOutOfBoundsException
//s.codePointCount(0, 4); // IndexOutOfBoundsException
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = surrogate + "ab";
System.out.println(s); // "𩸽ab"
System.out.println(s.codePointCount(0, 1)); // 1
System.out.println(s.codePointCount(0, 2)); // 1
System.out.println(s.codePointCount(0, 3)); // 2
System.out.println(s.codePointCount(0, 4)); // 3
//s.codePointCount(0, 5); // IndexOutOfBoundsException
IntStream codePoints ()
Returns a stream of code point values from this sequence.
// Unicode : 0x61 = a, 0x62 = b, 0x63 = c, 0x64 = d, 0x65 = e
final var ret = "abcde".codePoints();
// [61, 62, 63, 64, 65]
System.out.println(ret.mapToObj(Integer::toHexString).toList());
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = "ab" + surrogate;
System.out.println(s); // "ab𩸽"
final var ret = s.codePoints();
ret.forEach(c -> {
System.out.println("%x : %c".formatted(c, c));
});
// Result
// ↓
// "61 : a"
// "62 : b"
// "29e3d : 𩸽"
int compareTo (String anotherString)
Compares two strings lexicographically.
System.out.println("Cake".compareTo("Book")); // 1
System.out.println("Cake".compareTo("Stone")); // -16
System.out.println("Book".compareTo("Book")); // 0
System.out.println("Book".compareTo("book")); // -32
System.out.println("a".compareTo("a")); // 0
System.out.println("a".compareTo("A")); // 32
System.out.println("A".compareTo("a")); // -32
System.out.println("A".compareTo("A")); // 0
System.out.println("a".compareTo("b")); // -1
System.out.println("b".compareTo("a")); // 1
System.out.println("A".compareTo("b")); // -33
System.out.println("b".compareTo("A")); // 33
System.out.println("a".compareTo("B")); // 31
System.out.println("B".compareTo("a")); // -31
int compareToIgnoreCase (String str)
Compares two strings lexicographically, ignoring case differences.
System.out.println("Cake".compareToIgnoreCase("Book")); // 1
System.out.println("Cake".compareToIgnoreCase("Stone")); // -16
System.out.println("Book".compareToIgnoreCase("Book")); // 0
System.out.println("Book".compareToIgnoreCase("book")); // 0
System.out.println("a".compareToIgnoreCase("a")); // 0
System.out.println("a".compareToIgnoreCase("A")); // 0
System.out.println("A".compareToIgnoreCase("a")); // 0
System.out.println("A".compareToIgnoreCase("A")); // 0
System.out.println("a".compareToIgnoreCase("b")); // -1
System.out.println("b".compareToIgnoreCase("a")); // 1
System.out.println("A".compareToIgnoreCase("b")); // -1
System.out.println("b".compareToIgnoreCase("A")); // 1
System.out.println("a".compareToIgnoreCase("B")); // -1
System.out.println("B".compareToIgnoreCase("a")); // 1
String concat (String str)
Concatenates the specified string to the end of this string.
final var ret1 = "cares".concat("s");
System.out.println(ret1); // "caress"
final var ret2 = "to".concat("get").concat("her");
System.out.println(ret2); // "together"
boolean contains (CharSequence s)
Returns true if and only if this string contains the specified sequence of char values.
final var s = "abcde";
System.out.println(s.contains("a")); // true
System.out.println(s.contains("abc")); // true
System.out.println(s.contains("z")); // false
System.out.println(s.contains("ace")); // false
boolean contentEquals (CharSequence cs)
Compares this string to the specified CharSequence.
final var s = "abc";
System.out.println(s.contentEquals("abc")); // true
System.out.println(s.contentEquals("xyz")); // false
final var cs = new StringBuilder();
cs.append('a');
System.out.println(s.contentEquals(cs)); // false
cs.append('b');
cs.append('c');
System.out.println(s.contentEquals(cs)); // true
boolean contentEquals (StringBuffer sb)
Compares this string to the specified StringBuffer.
final var s = "abc";
final var sb = new StringBuffer();
sb.append('a');
System.out.println(s.contentEquals(sb)); // false
sb.append('b');
sb.append('c');
System.out.println(s.contentEquals(sb)); // true
static String copyValueOf (char[] data)
Equivalent to valueOf(char[]).
final char[] data = {'a', 'b', 'c'};
final var ret = String.copyValueOf(data);
System.out.println(ret); // "abc"
static String copyValueOf (char[] data, int offset, int count)
Equivalent to valueOf(char[], int, int).
final char[] data = {'a', 'b', 'c'};
System.out.println(String.copyValueOf(data, 0, 0)); // ""
System.out.println(String.copyValueOf(data, 0, 1)); // "a"
System.out.println(String.copyValueOf(data, 0, 2)); // "ab"
System.out.println(String.copyValueOf(data, 0, 3)); // "abc"
//String.copyValueOf(data, 0, 4); // IndexOutOfBoundsException
System.out.println(String.copyValueOf(data, 1, 2)); // "bc"
System.out.println(String.copyValueOf(data, 2, 1)); // "c"
Optional<String> describeConstable ()
Returns an Optional containing the nominal descriptor for this instance, which is the instance itself.
final var ret = "abcd".describeConstable();
System.out.println(ret); // Optional[abcd]
boolean endsWith (String suffix)
Tests if this string ends with the specified suffix.
final var s = "abcd";
System.out.println(s.endsWith("abcd")); // true
System.out.println(s.endsWith("bcd")); // true
System.out.println(s.endsWith("cd")); // true
System.out.println(s.endsWith("d")); // true
System.out.println(s.endsWith("")); // true
System.out.println(s.endsWith("a")); // false
System.out.println(s.endsWith("ab")); // false
System.out.println(s.endsWith("abc")); // false
boolean equals (Object anObject)
Compares this string to the specified object.
final var s = "abc";
System.out.println(s.equals("")); // false
System.out.println(s.equals("a")); // false
System.out.println(s.equals("ab")); // false
System.out.println(s.equals("abc")); // true
System.out.println(s.equals("abcd")); // false
System.out.println(s.equals("ABC")); // false
final var s = "abc";
final var sb = new StringBuilder("abc");
System.out.println(s.equals(sb)); // false
System.out.println(s.contentEquals(sb)); // true
boolean equalsIgnoreCase (String anotherString)
Compares this String to another String, ignoring case considerations.
final var s = "abc";
System.out.println(s.equalsIgnoreCase("")); // false
System.out.println(s.equalsIgnoreCase("a")); // false
System.out.println(s.equalsIgnoreCase("ab")); // false
System.out.println(s.equalsIgnoreCase("abc")); // true
System.out.println(s.equalsIgnoreCase("abcd")); // false
System.out.println(s.equalsIgnoreCase("ABC")); // true
static String format (String format, Object... args)
Returns a formatted string using the specified format string and arguments.
System.out.println(String.format("b : %b", true)); // "b : true"
System.out.println(String.format("B : %B", false)); // "B : FALSE"
System.out.println(String.format("h : %h", "abcd")); // "h : 2d9442"
System.out.println(String.format("H : %H", LocalTime.of(12, 30))); // "H : 6103F8ED"
System.out.println(String.format("s : %s", "abcd")); // "s : abcd"
System.out.println(String.format("S : %S", "abcd")); // "S : ABCD"
System.out.println(String.format("c : %c", 'z')); // "c : z"
System.out.println(String.format("C : %C", 'z')); // "C : Z"
System.out.println(String.format("d : %d", 123)); // "d : 123"
System.out.println(String.format("o : %o", 123)); // "o : 173"
System.out.println(String.format("x : %x", 123)); // "x : 7b"
System.out.println(String.format("X : %X", 123)); // "X : 7B"
System.out.println(String.format("e : %e", 0.12)); // "e : 1.200000e-01"
System.out.println(String.format("E : %E", 0.12)); // "E : 1.200000E-01"
System.out.println(String.format("f : %f", 1.400004)); // "f : 1.400004"
System.out.println(String.format("g : %g", 1.400004)); // "g : 1.40000"
System.out.println(String.format("a : %a", 0.12)); // "a : 0x1.eb851eb851eb8p-4"
System.out.println(String.format("A : %A", 0.12)); // "A : 0X1.EB851EB851EB8P-4"
final var date = LocalDate.of(2021, 3, 10);
System.out.println(date); // 2021-03-10
System.out.println(String.format("%tY %tm %te", date, date, date)); // "2021 03 10"
static String format (Locale l, String format, Object... args)
Returns a formatted string using the specified locale, format string, and arguments.
final var date = LocalDate.of(2021, 3, 10);
System.out.println(date); // 2021-03-10
final var ret = String.format(Locale.ENGLISH, "%tY %tB %te %tA", date, date, date, date);
System.out.println(ret); // 2021 March 10 Wednesday
String formatted (Object... args)
Formats using this string as the format string, and the supplied arguments.
System.out.println("b : %b".formatted(true)); // "b : true"
System.out.println("B : %B".formatted(false)); // "B : FALSE"
System.out.println("h : %h".formatted("abcd")); // "h : 2d9442"
System.out.println("H : %H".formatted(LocalTime.of(12, 30))); // "H : 6103F8ED"
System.out.println("s : %s".formatted("abcd")); // "s : abcd"
System.out.println("S : %S".formatted("abcd")); // "S : ABCD"
System.out.println("c : %c".formatted('z')); // "c : z"
System.out.println("C : %C".formatted('z')); // "C : Z"
System.out.println("d : %d".formatted(123)); // "d : 123"
System.out.println("o : %o".formatted(123)); // "o : 173"
System.out.println("x : %x".formatted(123)); // "x : 7b"
System.out.println("X : %X".formatted(123)); // "X : 7B"
System.out.println("e : %e".formatted(0.12)); // "e : 1.200000e-01"
System.out.println("E : %E".formatted(0.12)); // "E : 1.200000E-01"
System.out.println("f : %f".formatted(1.400004)); // "f : 1.400004"
System.out.println("g : %g".formatted(1.400004)); // "g : 1.40000"
System.out.println("a : %a".formatted(0.12)); // "a : 0x1.eb851eb851eb8p-4"
System.out.println("A : %A".formatted(0.12)); // "A : 0X1.EB851EB851EB8P-4"
final var date = LocalDate.of(2021, 3, 10);
System.out.println(date); // 2021-03-10
System.out.println("%tY %tm %te".formatted(date, date, date)); // "2021 03 10"
byte[] getBytes ()
Encodes this String into a sequence of bytes using the default charset, storing the result into a new byte array.
final var ret = "abcd".getBytes();
// [97, 98, 99, 100]
System.out.println(Arrays.toString(ret));
System.out.println(Charset.defaultCharset()); // UTF-8
final var s = "あいうえお";
final var ret = s.getBytes();
// [-29, -127, -126, -29, -127, -124, -29, -127, -122, -29, -127, -120, -29, -127, -118]
System.out.println(Arrays.toString(ret));
final var utf8 = s.getBytes(StandardCharsets.UTF_8);
System.out.println(Arrays.equals(ret, utf8)); // true
final var sjis = s.getBytes("Shift_JIS");
System.out.println(Arrays.equals(ret, sjis)); // false
void getBytes (int srcBegin, int srcEnd, byte[] dst, int dstBegin)
Deprecated. This method does not properly convert characters into bytes.
Deprecated.
byte[] getBytes (String charsetName)
Encodes this String into a sequence of bytes using the named charset, storing the result into a new byte array.
final var ret = "abcd".getBytes("UTF-8");
// [97, 98, 99, 100]
System.out.println(Arrays.toString(ret));
final var s = "あいうえお";
final var utf8 = s.getBytes("UTF-8");
// [-29, -127, -126, -29, -127, -124, -29, -127, -122, -29, -127, -120, -29, -127, -118]
System.out.println(Arrays.toString(utf8));
System.out.println(new String(utf8, "UTF-8")); // "あいうえお"
final var sjis = s.getBytes("Shift_JIS");
// [-126, -96, -126, -94, -126, -92, -126, -90, -126, -88]
System.out.println(Arrays.toString(sjis));
System.out.println(new String(sjis, "Shift_JIS")); // "あいうえお"
byte[] getBytes (Charset charset)
Encodes this String into a sequence of bytes using the given charset, storing the result into a new byte array.
final var ret = "abcd".getBytes(StandardCharsets.UTF_8);
// [97, 98, 99, 100]
System.out.println(Arrays.toString(ret));
final var s = "あいうえお";
final var utf8 = s.getBytes(StandardCharsets.UTF_8);
// [-29, -127, -126, -29, -127, -124, -29, -127, -122, -29, -127, -120, -29, -127, -118]
System.out.println(Arrays.toString(utf8));
System.out.println(new String(utf8, StandardCharsets.UTF_8)); // "あいうえお"
final var sjis = s.getBytes(Charset.forName("Shift_JIS"));
// [-126, -96, -126, -94, -126, -92, -126, -90, -126, -88]
System.out.println(Arrays.toString(sjis));
System.out.println(new String(sjis, Charset.forName("Shift_JIS"))); // "あいうえお"
void getChars (int srcBegin, int srcEnd, char[] dst, int dstBegin)
Copies characters from this string into the destination character array.
final var s = "abcde";
final var chars1 = new char[5];
s.getChars(0, 5, chars1, 0);
System.out.println(Arrays.toString(chars1)); // [a, b, c, d, e]
final var chars2 = new char[5];
s.getChars(1, 3, chars2, 0);
System.out.println(Arrays.toString(chars2)); // [b, c, , , ]
final var chars3 = new char[5];
s.getChars(0, 2, chars3, 3);
System.out.println(Arrays.toString(chars3)); // [ , , , a, b]
int hashCode ()
Returns a hash code for this string.
System.out.println("".hashCode()); // 0
System.out.println("a".hashCode()); // 97
System.out.println("ab".hashCode()); // 3105
System.out.println("123".hashCode()); // 48690
final var s = """
abcdefghijklmnopqrstuvwxyz
ABCDEFGHIJKLMNOPQRSTUVWXYZ
123456790
""";
System.out.println(s.hashCode()); // 573751039
String indent (int n)
Adjusts the indentation of each line of this string based on the value of n, and normalizes line termination characters.
final var s = """
Book
Cake
Tree
Stone
""";
// """
// Cake
// Tree
// Stone
// """
System.out.println(s);
// """
// Book
// Cake
// Tree
// Stone
// """
System.out.println(s.indent(0));
// """
// Book
// Cake
// Tree
// Stone
// """
System.out.println(s.indent(1));
// """
// Book
// Cake
// Tree
// Stone
// """
System.out.println(s.indent(2));
int indexOf (int ch)
Returns the index within this string of the first occurrence of the specified character.
final var s = "abcXY";
System.out.println(s.indexOf('a')); // 0
System.out.println(s.indexOf('b')); // 1
System.out.println(s.indexOf('c')); // 2
System.out.println(s.indexOf('d')); // -1
System.out.println(s.indexOf('X')); // 3
System.out.println(s.indexOf('Y')); // 4
System.out.println(s.indexOf('Z')); // -1
final var s = "abcabc";
System.out.println(s.indexOf('a')); // 0
System.out.println(s.indexOf('b')); // 1
System.out.println(s.indexOf('c')); // 2
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = "a" + surrogate + "b";
System.out.println(s); // "a𩸽b"
System.out.println(s.indexOf('a')); // 0
// 0x29e3d = 𩸽
System.out.println(s.indexOf(0x29e3d)); // 1
System.out.println(s.indexOf('b')); // 3
int indexOf (int ch, int fromIndex)
Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index.
final var s = "abcabc";
System.out.println(s.indexOf('a', -1)); // 0
System.out.println(s.indexOf('a', 0)); // 0
System.out.println(s.indexOf('a', 1)); // 3
System.out.println(s.indexOf('a', 2)); // 3
System.out.println(s.indexOf('a', 3)); // 3
System.out.println(s.indexOf('a', 4)); // -1
System.out.println(s.indexOf('a', 5)); // -1
System.out.println(s.indexOf('a', 6)); // -1
System.out.println(s.indexOf('b', 0)); // 1
System.out.println(s.indexOf('b', 1)); // 1
System.out.println(s.indexOf('b', 2)); // 4
System.out.println(s.indexOf('b', 3)); // 4
System.out.println(s.indexOf('b', 4)); // 4
System.out.println(s.indexOf('b', 5)); // -1
System.out.println(s.indexOf('c', 0)); // 2
System.out.println(s.indexOf('c', 1)); // 2
System.out.println(s.indexOf('c', 2)); // 2
System.out.println(s.indexOf('c', 3)); // 5
System.out.println(s.indexOf('c', 4)); // 5
System.out.println(s.indexOf('c', 5)); // 5
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = "a" + surrogate + "b";
System.out.println(s); // "a𩸽b"
System.out.println(s.indexOf('a', 0)); // 0
System.out.println(s.indexOf('a', 1)); // -1
System.out.println(s.indexOf('a', 2)); // -1
System.out.println(s.indexOf('a', 3)); // -1
// 0x29e3d = 𩸽
System.out.println(s.indexOf(0x29e3d, 0)); // 1
System.out.println(s.indexOf(0x29e3d, 1)); // 1
System.out.println(s.indexOf(0x29e3d, 2)); // -1
System.out.println(s.indexOf(0x29e3d, 3)); // -1
System.out.println(s.indexOf('b', 0)); // 3
System.out.println(s.indexOf('b', 1)); // 3
System.out.println(s.indexOf('b', 2)); // 3
System.out.println(s.indexOf('b', 3)); // 3
System.out.println(s.indexOf('b', 4)); // -1
int indexOf (String str)
Returns the index within this string of the first occurrence of the specified substring.
final var s = "abcabc";
System.out.println(s.indexOf("a")); // 0
System.out.println(s.indexOf("ab")); // 0
System.out.println(s.indexOf("abc")); // 0
System.out.println(s.indexOf("bc")); // 1
System.out.println(s.indexOf("c")); // 2
System.out.println(s.indexOf("cab")); // 2
System.out.println(s.indexOf("abcd")); // -1
System.out.println(s.indexOf("ac")); // -1
System.out.println(s.indexOf("z")); // -1
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = "a" + surrogate + "b";
System.out.println(s); // "a𩸽b"
System.out.println(s.indexOf("a")); // 0
System.out.println(s.indexOf(surrogate)); // 1
System.out.println(s.indexOf("b")); // 3
int indexOf (String str, int fromIndex)
Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.
final var s = "abcabc";
System.out.println(s.indexOf("ab", -1)); // 0
System.out.println(s.indexOf("ab", 0)); // 0
System.out.println(s.indexOf("ab", 1)); // 3
System.out.println(s.indexOf("ab", 2)); // 3
System.out.println(s.indexOf("ab", 3)); // 3
System.out.println(s.indexOf("ab", 4)); // -1
System.out.println(s.indexOf("ab", 5)); // -1
System.out.println(s.indexOf("ab", 6)); // -1
System.out.println(s.indexOf("bc", 0)); // 1
System.out.println(s.indexOf("bc", 1)); // 1
System.out.println(s.indexOf("bc", 2)); // 4
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = "a" + surrogate + "b";
System.out.println(s); // "a𩸽b"
System.out.println(s.indexOf("a", 0)); // 0
System.out.println(s.indexOf("a", 1)); // -1
System.out.println(s.indexOf(surrogate, 0)); // 1
System.out.println(s.indexOf(surrogate, 1)); // 1
System.out.println(s.indexOf(surrogate, 2)); // -1
System.out.println(s.indexOf(surrogate, 3)); // -1
System.out.println(s.indexOf("b", 0)); // 3
System.out.println(s.indexOf("b", 1)); // 3
System.out.println(s.indexOf("b", 2)); // 3
System.out.println(s.indexOf("b", 3)); // 3
System.out.println(s.indexOf("b", 4)); // -1
String intern ()
Returns a canonical representation for the string object.
final var s1 = new String("abc");
final var s2 = new String("abc");
final var ret1 = s1.intern();
System.out.println(ret1); // "abc"
final var ret2 = s2.intern();
System.out.println(ret2); // "abc"
System.out.println(s1 == s2); // false
System.out.println(s1.equals(s2)); // true
System.out.println(ret1 == ret2); // true
boolean isBlank ()
Returns true if the string is empty or contains only white space codepoints, otherwise false.
System.out.println("".isBlank()); // true
System.out.println(" ".isBlank()); // true
System.out.println(" ".isBlank()); // true
System.out.println("\t".isBlank()); // true
System.out.println("\n".isBlank()); // true
System.out.println("abc".isBlank()); // false
System.out.println("a b c".isBlank()); // false
boolean isEmpty ()
Returns true if, and only if, length() is 0.
System.out.println("".isEmpty()); // true
System.out.println(" ".isEmpty()); // false
System.out.println("\n".isEmpty()); // false
System.out.println("\0".isEmpty()); // false
System.out.println("abc".isEmpty()); // false
static String join (CharSequence delimiter, CharSequence... elements)
Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter.
System.out.println(String.join("-", "Java", "is", "cool")); // "Java-is-cool"
System.out.println(String.join("->", "A", "B", "C")); // "A->B->C"
System.out.println(String.join("-")); // ""
System.out.println(String.join("-", "", "a", "", "b")); // "-a--b"
static String join (CharSequence delimiter, Iterable<? extends CharSequence> elements)
Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter.
System.out.println(String.join("-", List.of("Java", "is", "cool"))); // "Java-is-cool"
System.out.println(String.join("->", List.of("A", "B", "C"))); // "A->B->C"
System.out.println(String.join("-", List.of())); // ""
System.out.println(String.join("-", List.of("", "a", "", "b"))); // "-a--b"
int lastIndexOf (int ch)
Returns the index within this string of the last occurrence of the specified character.
final var s = "abcXY";
System.out.println(s.lastIndexOf('a')); // 0
System.out.println(s.lastIndexOf('b')); // 1
System.out.println(s.lastIndexOf('c')); // 2
System.out.println(s.lastIndexOf('d')); // -1
System.out.println(s.lastIndexOf('X')); // 3
System.out.println(s.lastIndexOf('Y')); // 4
System.out.println(s.lastIndexOf('Z')); // -1
final var s = "abcabc";
System.out.println(s.lastIndexOf('a')); // 3
System.out.println(s.lastIndexOf('b')); // 4
System.out.println(s.lastIndexOf('c')); // 5
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = "a" + surrogate + "b";
System.out.println(s); // "a𩸽b"
System.out.println(s.lastIndexOf('a')); // 0
// 0x29e3d = 𩸽
System.out.println(s.lastIndexOf(0x29e3d)); // 1
System.out.println(s.lastIndexOf('b')); // 3
int lastIndexOf (int ch, int fromIndex)
Returns the index within this string of the last occurrence of the specified character, searching backward starting at the specified index.
final var s = "abcabc";
System.out.println(s.lastIndexOf('a', 5)); // 3
System.out.println(s.lastIndexOf('a', 4)); // 3
System.out.println(s.lastIndexOf('a', 3)); // 3
System.out.println(s.lastIndexOf('a', 2)); // 0
System.out.println(s.lastIndexOf('a', 1)); // 0
System.out.println(s.lastIndexOf('a', 0)); // 0
System.out.println(s.lastIndexOf('b', 5)); // 4
System.out.println(s.lastIndexOf('b', 4)); // 4
System.out.println(s.lastIndexOf('b', 3)); // 1
System.out.println(s.lastIndexOf('b', 2)); // 1
System.out.println(s.lastIndexOf('b', 1)); // 1
System.out.println(s.lastIndexOf('b', 0)); // -1
System.out.println(s.lastIndexOf('c', 5)); // 5
System.out.println(s.lastIndexOf('c', 4)); // 2
System.out.println(s.lastIndexOf('c', 3)); // 2
System.out.println(s.lastIndexOf('c', 2)); // 2
System.out.println(s.lastIndexOf('c', 1)); // -1
System.out.println(s.lastIndexOf('c', 0)); // -1
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = "a" + surrogate + "b";
System.out.println(s); // "a𩸽b"
System.out.println(s.lastIndexOf('a', 3)); // 0
System.out.println(s.lastIndexOf('a', 2)); // 0
System.out.println(s.lastIndexOf('a', 1)); // 0
System.out.println(s.lastIndexOf('a', 0)); // 0
// 0x29e3d = 𩸽
System.out.println(s.lastIndexOf(0x29e3d, 3)); // 1
System.out.println(s.lastIndexOf(0x29e3d, 2)); // 1
System.out.println(s.lastIndexOf(0x29e3d, 1)); // 1
System.out.println(s.lastIndexOf(0x29e3d, 0)); // -1
System.out.println(s.lastIndexOf('b', 4)); // 3
System.out.println(s.lastIndexOf('b', 3)); // 3
System.out.println(s.lastIndexOf('b', 2)); // -1
System.out.println(s.lastIndexOf('b', 1)); // -1
System.out.println(s.lastIndexOf('b', 0)); // -1
int lastIndexOf (String str)
Returns the index within this string of the last occurrence of the specified substring.
final var s = "abcabc";
System.out.println(s.lastIndexOf("a")); // 3
System.out.println(s.lastIndexOf("ab")); // 3
System.out.println(s.lastIndexOf("abc")); // 3
System.out.println(s.lastIndexOf("bc")); // 4
System.out.println(s.lastIndexOf("c")); // 5
System.out.println(s.lastIndexOf("cab")); // 2
System.out.println(s.lastIndexOf("abcd")); // -1
System.out.println(s.lastIndexOf("ac")); // -1
System.out.println(s.lastIndexOf("z")); // -1
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = "a" + surrogate + "b";
System.out.println(s); // "a𩸽b"
System.out.println(s.lastIndexOf("a")); // 0
System.out.println(s.lastIndexOf(surrogate)); // 1
System.out.println(s.lastIndexOf("b")); // 3
int lastIndexOf (String str, int fromIndex)
Returns the index within this string of the last occurrence of the specified substring, searching backward starting at the specified index.
final var s = "abcabc";
System.out.println(s.lastIndexOf("ab", 5)); // 3
System.out.println(s.lastIndexOf("ab", 4)); // 3
System.out.println(s.lastIndexOf("ab", 3)); // 3
System.out.println(s.lastIndexOf("ab", 2)); // 0
System.out.println(s.lastIndexOf("ab", 1)); // 0
System.out.println(s.lastIndexOf("ab", 0)); // 0
System.out.println(s.lastIndexOf("bc", 5)); // 4
System.out.println(s.lastIndexOf("bc", 4)); // 4
System.out.println(s.lastIndexOf("bc", 3)); // 1
System.out.println(s.lastIndexOf("bc", 2)); // 1
System.out.println(s.lastIndexOf("bc", 1)); // 1
System.out.println(s.lastIndexOf("bc", 0)); // -1
System.out.println(s.lastIndexOf("ca", 5)); // 2
System.out.println(s.lastIndexOf("ca", 4)); // 2
System.out.println(s.lastIndexOf("ca", 3)); // 2
System.out.println(s.lastIndexOf("ca", 2)); // 2
System.out.println(s.lastIndexOf("ca", 1)); // -1
System.out.println(s.lastIndexOf("ca", 0)); // -1
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = "a" + surrogate + "b";
System.out.println(s); // "a𩸽b"
System.out.println(s.lastIndexOf("a", 3)); // 0
System.out.println(s.lastIndexOf("a", 2)); // 0
System.out.println(s.lastIndexOf("a", 1)); // 0
System.out.println(s.lastIndexOf("a", 0)); // 0
System.out.println(s.lastIndexOf(surrogate, 3)); // 1
System.out.println(s.lastIndexOf(surrogate, 2)); // 1
System.out.println(s.lastIndexOf(surrogate, 1)); // 1
System.out.println(s.lastIndexOf(surrogate, 0)); // -1
System.out.println(s.lastIndexOf("b", 3)); // 3
System.out.println(s.lastIndexOf("b", 2)); // -1
System.out.println(s.lastIndexOf("b", 1)); // -1
System.out.println(s.lastIndexOf("b", 0)); // -1
int length ()
Returns the length of this string.
System.out.println("".length()); // 0
System.out.println("abc".length()); // 3
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = "a" + surrogate + "b";
System.out.println(s); // "a𩸽b"
System.out.println(s.length()); // 4
System.out.println(s.codePoints().count()); // 3
Stream<String> lines ()
Returns a stream of lines extracted from this string, separated by line terminators.
final var s = """
Book
Cake
Stone
""";
final var ret = s.lines();
System.out.println(ret.toList()); // [Book, Cake, Stone]
final var s = """
Book
Cake
Stone
""";
final var ret = s.lines();
System.out.println(ret.toList()); // [, Book, , Cake, , Stone, ]
final var ret = "".lines();
System.out.println(ret.toList()); // []
boolean matches (String regex)
Tells whether or not this string matches the given regular expression.
final var s = "java is cool";
System.out.println(s.matches("java")); // false
System.out.println(s.matches("java.*")); // true
System.out.println(s.matches(".*cool")); // true
final var s1 = "Book";
final var s2 = "Cake";
final var s3 = "Stone";
System.out.println(s1.matches("Book|Cake")); // true
System.out.println(s2.matches("Book|Cake")); // true
System.out.println(s3.matches("Book|Cake")); // false
int offsetByCodePoints (int index, int codePointOffset)
Returns the index within this String that is offset from the given index by codePointOffset code points.
final var s = "abc";
//s.offsetByCodePoints(0, -1); // IndexOutOfBoundsException
System.out.println(s.offsetByCodePoints(0, 0)); // 0
System.out.println(s.offsetByCodePoints(0, 1)); // 1
System.out.println(s.offsetByCodePoints(0, 2)); // 2
System.out.println(s.offsetByCodePoints(0, 3)); // 3
System.out.println(s.offsetByCodePoints(1, 0)); // 1
System.out.println(s.offsetByCodePoints(1, 1)); // 2
System.out.println(s.offsetByCodePoints(1, 2)); // 3
final var surrogate = "\uD867\uDE3D"; // "𩸽" is one character.
System.out.println(surrogate); // "𩸽"
final var s = "a" + surrogate + "b";
System.out.println(s); // "a𩸽b"
System.out.println(s.offsetByCodePoints(0, 0)); // 0
System.out.println(s.offsetByCodePoints(0, 1)); // 1
System.out.println(s.offsetByCodePoints(0, 2)); // 3
System.out.println(s.offsetByCodePoints(0, 3)); // 4
boolean regionMatches (boolean ignoreCase, int toffset, String other, int ooffset, int len)
Tests if two string regions are equal.
final var s = "abcde";
// ignoreCase is false.
System.out.println(s.regionMatches(false, 0, "abcde", 0, 5)); // true
System.out.println(s.regionMatches(false, 0, "bcdef", 0, 5)); // false
System.out.println(s.regionMatches(false, 0, "ABCDE", 0, 5)); // false
System.out.println(s.regionMatches(false, 0, "bcd", 0, 3)); // false
System.out.println(s.regionMatches(false, 1, "bcd", 0, 3)); // true
System.out.println(s.regionMatches(false, 2, "bcd", 0, 3)); // false
System.out.println(s.regionMatches(false, 0, "012abcde345", 0, 11)); // false
System.out.println(s.regionMatches(false, 0, "012abcde345", 0, 5)); // false
System.out.println(s.regionMatches(false, 0, "012abcde345", 3, 5)); // true
// ignoreCase is true.
System.out.println(s.regionMatches(true, 0, "abcde", 0, 5)); // true
System.out.println(s.regionMatches(true, 0, "bcdef", 0, 5)); // false
System.out.println(s.regionMatches(true, 0, "ABCDE", 0, 5)); // true
boolean regionMatches (int toffset, String other, int ooffset, int len)
Tests if two string regions are equal.
final var s = "abcde";
System.out.println(s.regionMatches(0, "abcde", 0, 5)); // true
System.out.println(s.regionMatches(0, "bcdef", 0, 5)); // false
System.out.println(s.regionMatches(0, "ABCDE", 0, 5)); // false
System.out.println(s.regionMatches(0, "bcd", 0, 3)); // false
System.out.println(s.regionMatches(1, "bcd", 0, 3)); // true
System.out.println(s.regionMatches(2, "bcd", 0, 3)); // false
System.out.println(s.regionMatches(0, "012abcde345", 0, 11)); // false
System.out.println(s.regionMatches(0, "012abcde345", 0, 5)); // false
System.out.println(s.regionMatches(0, "012abcde345", 3, 5)); // true
String repeat (int count)
Returns a string whose value is the concatenation of this string repeated count times.
System.out.println("A".repeat(0)); // ""
System.out.println("A".repeat(1)); // "A"
System.out.println("A".repeat(2)); // "AA"
System.out.println("A".repeat(3)); // "AAA"
System.out.println("abc".repeat(0)); // ""
System.out.println("abc".repeat(1)); // "abc"
System.out.println("abc".repeat(2)); // "abcabc"
System.out.println("".repeat(0)); // ""
System.out.println("".repeat(1)); // ""
String replace (char oldChar, char newChar)
Returns a string resulting from replacing all occurrences of oldChar in this string with newChar.
final var s = "abcd";
System.out.println(s.replace('a', 'X')); // "Xbcd"
System.out.println(s.replace('b', 'Y')); // "aYcd"
System.out.println(s.replace('c', 'Z')); // "abZd"
final var s = "aabbcc";
System.out.println(s.replace('a', 'X')); // "XXbbcc"
System.out.println(s.replace('b', 'Y')); // "aaYYcc"
String replace (CharSequence target, CharSequence replacement)
Replaces each substring of this string that matches the literal target sequence with the specified literal replacement sequence.
final var s = "abcd";
System.out.println(s.replace("a", "X")); // "Xbcd"
System.out.println(s.replace("abc", "XYZ")); // "XYZd"
System.out.println(s.replace("ab", "")); // "cd"
final var s = "abcabc";
System.out.println(s.replace("a", "X")); // "XbcXbc"
System.out.println(s.replace("bc", "YYZZ")); // "aYYZZaYYZZ"
String replaceAll (String regex, String replacement)
Replaces each substring of this string that matches the given regular expression with the given replacement.
final var s = "javaAAABBB";
System.out.println(s.replaceAll("java.", "x")); // "xAABBB"
System.out.println(s.replaceAll("A.", "y")); // "javayyBB"
System.out.println(s.replaceAll(".", "z")); // "zzzzzzzzzz"
String replaceFirst (String regex, String replacement)
Replaces the first substring of this string that matches the given regular expression with the given replacement.
final var s = "javaAAABBB";
System.out.println(s.replaceFirst("java.", "x")); // "xAABBB"
System.out.println(s.replaceFirst("A.", "y")); // "javayABBB"
System.out.println(s.replaceFirst(".", "z")); // "zavaAAABBB"
String resolveConstantDesc (MethodHandles.Lookup lookup)
Resolves this instance as a ConstantDesc, the result of which is the instance itself.
final var ret = "abcd".resolveConstantDesc(MethodHandles.lookup());
System.out.println(ret); // "abcd"
String[] split (String regex)
Splits this string around matches of the given regular expression.
final var s = "a-b-c";
System.out.println(Arrays.toString(s.split("-"))); // [a, b, c]
System.out.println(Arrays.toString(s.split("b"))); // [a-, -c]
System.out.println(Arrays.toString(s.split("X"))); // [a-b-c]
final var s = "boo:and:foo";
System.out.println(Arrays.toString(s.split(":"))); // [boo, and, foo]
System.out.println(Arrays.toString(s.split("o"))); // [b, , :and:f]
final var s = "a-b>c";
System.out.println(Arrays.toString(s.split("-"))); // [a, b>c]
System.out.println(Arrays.toString(s.split(">"))); // [a-b, c]
System.out.println(Arrays.toString(s.split("(-|>)"))); // [a, b, c]
String[] split (String regex, int limit)
Splits this string around matches of the given regular expression.
final var s = "a-b-c";
System.out.println(Arrays.toString(s.split("-", 0))); // [a, b, c]
System.out.println(Arrays.toString(s.split("-", 1))); // [a-b-c]
System.out.println(Arrays.toString(s.split("-", 2))); // [a, b-c]
System.out.println(Arrays.toString(s.split("-", 3))); // [a, b, c]
final var s = "boo:and:foo";
System.out.println(Arrays.toString(s.split(":", 2))); // [boo, and:foo]
System.out.println(Arrays.toString(s.split(":", 5))); // [boo, and, foo]
System.out.println(Arrays.toString(s.split(":", -2))); // [boo, and, foo]
System.out.println(Arrays.toString(s.split("o", 5))); // [b, , :and:f, , ]
System.out.println(Arrays.toString(s.split("o", -2))); // [b, , :and:f, , ]
System.out.println(Arrays.toString(s.split("o", 0))); // [b, , :and:f]
final var s = "a-b>c";
System.out.println(Arrays.toString(s.split("-", 1))); // [a-b>c]
System.out.println(Arrays.toString(s.split("-", 2))); // [a, b>c]
System.out.println(Arrays.toString(s.split("-", 3))); // [a, b>c]
System.out.println(Arrays.toString(s.split(">", 1))); // [a-b>c]
System.out.println(Arrays.toString(s.split(">", 2))); // [a-b, c]
System.out.println(Arrays.toString(s.split(">", 3))); // [a-b, c]
System.out.println(Arrays.toString(s.split("(-|>)", 1))); // [a-b>c]
System.out.println(Arrays.toString(s.split("(-|>)", 2))); // [a, b>c]
System.out.println(Arrays.toString(s.split("(-|>)", 3))); // [a, b, c]
boolean startsWith (String prefix)
Tests if this string starts with the specified prefix.
final var s = "abc";
System.out.println(s.startsWith("a")); // true
System.out.println(s.startsWith("ab")); // true
System.out.println(s.startsWith("abc")); // true
System.out.println(s.startsWith("abcd")); // false
System.out.println(s.startsWith("b")); // false
System.out.println(s.startsWith("c")); // false
boolean startsWith (String prefix, int toffset)
Tests if the substring of this string beginning at the specified index starts with the specified prefix.
final var s = "abc";
System.out.println(s.startsWith("a", 0)); // true
System.out.println(s.startsWith("a", 1)); // false
System.out.println(s.startsWith("a", 2)); // false
System.out.println(s.startsWith("ab", 0)); // true
System.out.println(s.startsWith("ab", 1)); // false
System.out.println(s.startsWith("ab", 2)); // false
System.out.println(s.startsWith("abc", 0)); // true
System.out.println(s.startsWith("abc", 1)); // false
System.out.println(s.startsWith("abc", 2)); // false
System.out.println(s.startsWith("b", 0)); // false
System.out.println(s.startsWith("b", 1)); // true
System.out.println(s.startsWith("b", 2)); // false
System.out.println(s.startsWith("bc", 0)); // false
System.out.println(s.startsWith("bc", 1)); // true
System.out.println(s.startsWith("bc", 2)); // false
System.out.println(s.startsWith("c", 0)); // false
System.out.println(s.startsWith("c", 1)); // false
System.out.println(s.startsWith("c", 2)); // true
String strip ()
Returns a string whose value is this string, with all leading and trailing white space removed.
Related method : trim().
final var ret = " abcd ".strip();
System.out.println(ret); // "abcd"
final var s = " \t\nABC \t\n";
// The function for whitespace readability.
final Function<String, String> func = (v) -> v.replace(" ", "*")
.replace("\t", "\\t")
.replace("\n", "\\n");
// "*\t\nABC*\t\n"
System.out.println(func.apply(s));
final var ret = s.strip();
// "ABC"
System.out.println(func.apply(ret));
final var s = " <html>\n" +
" <body>\n" +
" <p>Hello</p>\n" +
" </body>\n" +
" </html> ";
// The function for whitespace readability.
final Function<String, String> func = (v) -> v.replace(" ", "*");
// """
// **<html>
// ****<body>
// ******<p>Hello</p>
// ****</body>
// **</html>**
// """
System.out.println(func.apply(s));
final var ret = s.strip();
// """
// <html>
// ****<body>
// ******<p>Hello</p>
// ****</body>
// **</html>
// """
System.out.println(func.apply(ret));
String stripIndent ()
Returns a string whose value is this string, with incidental white space removed from the beginning and end of every line.
final var ret = " abcd ".stripIndent();
System.out.println(ret); // "abcd"
final var s = " \t\nABC \t\n";
// The function for whitespace readability.
final Function<String, String> func = (v) -> v.replace(" ", "*")
.replace("\t", "\\t")
.replace("\n", "\\n");
// "*\t\nABC*\t\n"
System.out.println(func.apply(s));
final var ret = s.stripIndent();
// "\nABC\n"
System.out.println(func.apply(ret));
final var s = " <html>\n" +
" <body>\n" +
" <p>Hello</p>\n" +
" </body>\n" +
" </html> ";
// The function for whitespace readability.
final Function<String, String> func = (v) -> v.replace(" ", "*");
// """
// **<html>
// ****<body>
// ******<p>Hello</p>
// ****</body>
// **</html>**
// """
System.out.println(func.apply(s));
final var ret = s.stripIndent();
// """
// <html>
// **<body>
// ****<p>Hello</p>
// **</body>
// </html>
// """
System.out.println(func.apply(ret));
String stripLeading ()
Returns a string whose value is this string, with all leading white space removed.
final var ret = " abcd ".stripLeading();
System.out.println(ret); // "abcd "
final var s = " \t\nABC \t\n";
// The function for whitespace readability.
final Function<String, String> func = (v) -> v.replace(" ", "*")
.replace("\t", "\\t")
.replace("\n", "\\n");
// "*\t\nABC*\t\n"
System.out.println(func.apply(s));
final var ret = s.stripLeading();
// "ABC*\t\n"
System.out.println(func.apply(ret));
final var s = " <html>\n" +
" <body>\n" +
" <p>Hello</p>\n" +
" </body>\n" +
" </html> ";
// The function for whitespace readability.
final Function<String, String> func = (v) -> v.replace(" ", "*");
// """
// **<html>
// ****<body>
// ******<p>Hello</p>
// ****</body>
// **</html>**
// """
System.out.println(func.apply(s));
final var ret = s.stripLeading();
// """
// <html>
// ****<body>
// ******<p>Hello</p>
// ****</body>
// **</html>**
// """
System.out.println(func.apply(ret));
String stripTrailing ()
Returns a string whose value is this string, with all trailing white space removed.
final var ret = " abcd ".stripTrailing();
System.out.println(ret); // " abcd"
final var s = " \t\nABC \t\n";
// The function for whitespace readability.
final Function<String, String> func = (v) -> v.replace(" ", "*")
.replace("\t", "\\t")
.replace("\n", "\\n");
// "*\t\nABC*\t\n"
System.out.println(func.apply(s));
final var ret = s.stripTrailing();
// "*\t\nABC"
System.out.println(func.apply(ret));
final var s = " <html>\n" +
" <body>\n" +
" <p>Hello</p>\n" +
" </body>\n" +
" </html> ";
// The function for whitespace readability.
final Function<String, String> func = (v) -> v.replace(" ", "*");
// """
// **<html>
// ****<body>
// ******<p>Hello</p>
// ****</body>
// **</html>**
// """
System.out.println(func.apply(s));
final var ret = s.stripTrailing();
// """
// **<html>
// ****<body>
// ******<p>Hello</p>
// ****</body>
// **</html>
// """
System.out.println(func.apply(ret));
CharSequence subSequence (int beginIndex, int endIndex)
Returns a character sequence that is a subsequence of this sequence.
final var s = "abcd";
System.out.println(s.subSequence(0, 0)); // ""
System.out.println(s.subSequence(0, 1)); // "a"
System.out.println(s.subSequence(0, 2)); // "ab"
System.out.println(s.subSequence(0, 3)); // "abc"
System.out.println(s.subSequence(0, 4)); // "abcd"
//s.subSequence(0, 5); // IndexOutOfBoundsException
System.out.println(s.subSequence(1, 2)); // "b"
System.out.println(s.subSequence(2, 4)); // "cd"
String substring (int beginIndex)
Returns a string that is a substring of this string.
final var s = "abcd";
System.out.println(s.substring(0)); // "abcd"
System.out.println(s.substring(1)); // "bcd"
System.out.println(s.substring(2)); // "cd"
System.out.println(s.substring(3)); // "d"
System.out.println(s.substring(4)); // ""
//s.substring(5); // IndexOutOfBoundsException
String substring (int beginIndex, int endIndex)
Returns a string that is a substring of this string.
final var s = "abcd";
System.out.println(s.substring(0, 0)); // ""
System.out.println(s.substring(0, 1)); // "a"
System.out.println(s.substring(0, 2)); // "ab"
System.out.println(s.substring(0, 3)); // "abc"
System.out.println(s.substring(0, 4)); // "abcd"
//s.substring(0, 5); // IndexOutOfBoundsException
System.out.println(s.substring(1, 2)); // "b"
System.out.println(s.substring(2, 4)); // "cd"
char[] toCharArray ()
Converts this string to a new character array.
final var ret1 = "".toCharArray();
System.out.println(Arrays.toString(ret1)); // []
final var ret2 = "abcd".toCharArray();
System.out.println(Arrays.toString(ret2)); // [a, b, c, d]
String toLowerCase ()
Converts all of the characters in this String to lower case using the rules of the default locale.
System.out.println(Locale.getDefault()); // en_US
System.out.println("".toLowerCase()); // ""
System.out.println("abcdef".toLowerCase()); // "abcdef"
System.out.println("ABCDEF".toLowerCase()); // "abcdef"
System.out.println("ΙΧΘΥΣ".toLowerCase()); // "ιχθυς"
String toLowerCase (Locale locale)
Converts all of the characters in this String to lower case using the rules of the given Locale.
final var s1 = "I"; // u0049
final var s2 = "İ"; // u0130
{
final var en = Locale.ENGLISH;
final var ret1 = s1.toLowerCase(en);
System.out.println(ret1); // "i"
System.out.println(ret1.codePoints().mapToObj(Integer::toHexString).toList()); // [69]
final var ret2 = s2.toLowerCase(en);
System.out.println(ret2); // "i̇ "
System.out.println(ret2.codePoints().mapToObj(Integer::toHexString).toList()); // [69, 307]
}
{
final var tr = new Locale("tr");
final var ret1 = s1.toLowerCase(tr);
System.out.println(ret1); // "ı"
System.out.println(ret1.codePoints().mapToObj(Integer::toHexString).toList()); // [131]
final var ret2 = s2.toLowerCase(tr);
System.out.println(ret2); // "i"
System.out.println(ret2.codePoints().mapToObj(Integer::toHexString).toList()); // [69]
}
String toString ()
This object (which is already a string!)
final var ret1 = "abcd".toString();
System.out.println(ret1); // "abcd"
final var ret2 = "XYZ".toString();
System.out.println(ret2); // "XYZ"
String toUpperCase ()
Converts all of the characters in this String to upper case using the rules of the default locale.
System.out.println(Locale.getDefault()); // en_US
System.out.println("".toUpperCase()); // ""
System.out.println("abcdef".toUpperCase()); // "ABCDEF"
System.out.println("ABCDEF".toUpperCase()); // "ABCDEF"
System.out.println("ιχθυς".toUpperCase()); // "ΙΧΘΥΣ"
String toUpperCase (Locale locale)
Converts all of the characters in this String to upper case using the rules of the given Locale.
final var s1 = "i"; // u0069
final var s2 = "ı"; // u0130
{
final var en = Locale.ENGLISH;
final var ret1 = s1.toUpperCase(en);
System.out.println(ret1); // "I"
System.out.println(ret1.codePoints().mapToObj(Integer::toHexString).toList()); // [49]
final var ret2 = s2.toUpperCase(en);
System.out.println(ret2); // "I"
System.out.println(ret2.codePoints().mapToObj(Integer::toHexString).toList()); // [49]
}
{
final var tr = new Locale("tr");
final var ret1 = s1.toUpperCase(tr);
System.out.println(ret1); // "İ"
System.out.println(ret1.codePoints().mapToObj(Integer::toHexString).toList()); // [130]
final var ret2 = s2.toUpperCase(tr);
System.out.println(ret2); // "I"
System.out.println(ret2.codePoints().mapToObj(Integer::toHexString).toList()); // [49]
}
<R> R transform (Function<? super String,? extends R> f)
This method allows the application of a function to this string.
final var s = "1234";
final var ret = s.transform(v -> Integer.parseInt(v) * 2);
System.out.println(ret); // 2468
final var s = "a";
final var ret = s.transform(v -> v.repeat(5).toUpperCase());
System.out.println(ret); // "AAAAA"
String translateEscapes ()
Returns a string whose value is this string, with escape sequences translated as if in a string literal.
final var s = "aaaa\\nBBBB";
System.out.println(s); // "aaaa\nBBBB"
// """
// aaaa
// BBBB
// """
System.out.println(s.translateEscapes());
String trim ()
Returns a string whose value is this string, with all leading and trailing space removed, where space is defined as any character whose codepoint is less than or equal to 'U+0020' (the space character).
Related method : strip().
final var ret = " abcd ".trim();
System.out.println(ret.trim()); // "abcd"
final var s = " \t\nABC \t\n";
// The function for whitespace readability.
final Function<String, String> func = (v) -> v.replace(" ", "*")
.replace("\t", "\\t")
.replace("\n", "\\n");
// "*\t\nABC*\t\n"
System.out.println(func.apply(s));
final var ret = s.trim();
// "ABC"
System.out.println(ret);
final var s = " <html>\n" +
" <body>\n" +
" <p>Hello</p>\n" +
" </body>\n" +
" </html> ";
// The function for whitespace readability.
final Function<String, String> func = (v) -> v.replace(" ", "*");
// """
// **<html>
// ****<body>
// ******<p>Hello</p>
// ****</body>
// **</html>**
// """
System.out.println(func.apply(s));
final var ret = s.trim();
// """
// <html>
// ****<body>
// ******<p>Hello</p>
// ****</body>
// **</html>
// """
System.out.println(func.apply(ret));
static String valueOf (boolean b)
Returns the string representation of the boolean argument.
final var ret1 = String.valueOf(true);
System.out.println(ret1); // "true"
final var ret2 = String.valueOf(false);
System.out.println(ret2); // "false"
static String valueOf (char c)
Returns the string representation of the char argument.
final var ret1 = String.valueOf('a');
System.out.println(ret1); // "a"
final var ret2 = String.valueOf('X');
System.out.println(ret2); // "X"
static String valueOf (char[] data)
Returns the string representation of the char array argument.
final char[] data = {'b', 'o', 'o', 'k'};
final var ret = String.valueOf(data);
System.out.println(ret); // "book"
static String valueOf (char[] data, int offset, int count)
Returns the string representation of a specific subarray of the char array argument.
final char[] data = {'b', 'o', 'o', 'k'};
System.out.println(String.valueOf(data, 0, 1)); // "b"
System.out.println(String.valueOf(data, 0, 2)); // "bo"
System.out.println(String.valueOf(data, 0, 3)); // "boo"
System.out.println(String.valueOf(data, 0, 4)); // "book"
System.out.println(String.valueOf(data, 1, 3)); // "ook"
System.out.println(String.valueOf(data, 2, 2)); // "ok"
System.out.println(String.valueOf(data, 3, 1)); // "k"
static String valueOf (double d)
Returns the string representation of the double argument.
final double d1 = 1.0;
final double d2 = 0.12345;
final double d3 = 1.23e10;
System.out.println(String.valueOf(d1)); // "1.0"
System.out.println(String.valueOf(d2)); // "0.12345"
System.out.println(String.valueOf(d3)); // "1.23E10"
static String valueOf (float f)
Returns the string representation of the float argument.
final float f1 = 1.0f;
final float f2 = 0.12345f;
final float f3 = 1.23e10f;
System.out.println(String.valueOf(f1)); // "1.0"
System.out.println(String.valueOf(f2)); // "0.12345"
System.out.println(String.valueOf(f3)); // "1.23E10"
static String valueOf (int i)
Returns the string representation of the int argument.
final int i1 = 0;
final int i2 = 1234;
final int i3 = -5678;
System.out.println(String.valueOf(i1)); // "0"
System.out.println(String.valueOf(i2)); // "1234"
System.out.println(String.valueOf(i3)); // "-5678"
static String valueOf (long l)
Returns the string representation of the long argument.
final long l1 = 0L;
final long l2 = 1234567890123456789L;
final long l3 = -5678901234L;
System.out.println(String.valueOf(l1)); // "0"
System.out.println(String.valueOf(l2)); // "1234567890123456789"
System.out.println(String.valueOf(l3)); // "-5678901234"
static String valueOf (Object obj)
Returns the string representation of the Object argument.
final var obj = LocalDate.of(2021, 3, 11);
final var ret = String.valueOf(obj);
System.out.println(ret); // "2021-03-11"
final var obj = new URL("https://example.com/");
final var ret = String.valueOf(obj);
System.out.println(ret); // "https://example.com/"