Java : OutputStreamWriter with Examples

OutputStreamWriter (Java SE 21 & JDK 21) with Examples.
You will find code examples on most OutputStreamWriter methods.

Summary

An OutputStreamWriter is a bridge from character streams to byte streams: Characters written to it are encoded into bytes using a specified charset. The charset that it uses may be specified by name or may be given explicitly, or the default charset may be accepted.

Class diagram

final var os = new ByteArrayOutputStream();

try (final var writer = new OutputStreamWriter(os)) {
    writer.write("abcd");
}

System.out.println(os); // abcd
System.out.println(Arrays.toString(os.toByteArray())); // [97, 98, 99, 100]

final var os = new ByteArrayOutputStream();

try (final var writer = new BufferedWriter(new OutputStreamWriter(os))) {
    writer.write("abcd");
    writer.newLine();
    writer.write("XYZ");
}

System.out.println(os);

// Result
// ↓
//abcd
//XYZ

Fields declared in Writer

lock

Please see the link below.

Writer with Examples

Constructors

OutputStreamWriter (OutputStream out)

Creates an OutputStreamWriter that uses the default character encoding, or where out is a PrintStream, the charset used by the print stream.

final var os = new ByteArrayOutputStream();

try (final var writer = new OutputStreamWriter(os)) {
    writer.write("abcd");
}

System.out.println(os); // abcd
System.out.println(Arrays.toString(os.toByteArray())); // [97, 98, 99, 100]

OutputStreamWriter (OutputStream out, String charsetName)

Creates an OutputStreamWriter that uses the named charset.

final var sjis = "Shift_JIS";
final var os = new ByteArrayOutputStream();

try (final var writer = new OutputStreamWriter(os, sjis)) {
    writer.write("○△×");
}

System.out.println(os.toString(sjis)); // ○△×

final var bytes = os.toByteArray();
System.out.println(Arrays.toString(bytes)); // [-127, -101, -127, -94, -127, 126]

OutputStreamWriter (OutputStream out, Charset cs)

Creates an OutputStreamWriter that uses the given charset.

final var sjis = Charset.forName("Shift_JIS");
final var os = new ByteArrayOutputStream();

try (final var writer = new OutputStreamWriter(os, sjis)) {
    writer.write("○△×");
}

System.out.println(os.toString(sjis)); // ○△×

final var bytes = os.toByteArray();
System.out.println(Arrays.toString(bytes)); // [-127, -101, -127, -94, -127, 126]

OutputStreamWriter (OutputStream out, CharsetEncoder enc)

Creates an OutputStreamWriter that uses the given charset encoder.

final var sjis = Charset.forName("Shift_JIS");
final var os = new ByteArrayOutputStream();

try (final var writer = new OutputStreamWriter(os, sjis.newEncoder())) {
    writer.write("○△×");
}

System.out.println(os.toString(sjis)); // ○△×

final var bytes = os.toByteArray();
System.out.println(Arrays.toString(bytes)); // [-127, -101, -127, -94, -127, 126]

Methods

void close ()

Closes the stream, flushing it first.

final var os = new ByteArrayOutputStream();

try (final var writer = new OutputStreamWriter(os)) {
    writer.write("abcd");
}

System.out.println(os); // abcd
System.out.println(Arrays.toString(os.toByteArray())); // [97, 98, 99, 100]

// An example without a try-with-resources statement.
final var os = new ByteArrayOutputStream();
final var writer = new OutputStreamWriter(os);
try {
    writer.write("abcd");
} finally {
    writer.close();
}

System.out.println(os); // abcd
System.out.println(Arrays.toString(os.toByteArray())); // [97, 98, 99, 100]

void flush ()

Flushes the stream.

final var os = new ByteArrayOutputStream();

try (final var writer = new OutputStreamWriter(os)) {
    writer.write("abcd");

    final var ret1 = os.toString();
    System.out.println(ret1.isEmpty()); // true

    writer.flush();

    final var ret2 = os.toString();
    System.out.println(ret2); // abcd

    writer.write("XYZ");

    final var ret3 = os.toString();
    System.out.println(ret3); // abcd
}

final var ret4 = os.toString();
System.out.println(ret4); // abcdXYZ

String getEncoding ()

Returns the name of the character encoding being used by this stream.

try (final var writer = new OutputStreamWriter(new ByteArrayOutputStream())) {
    final var ret = writer.getEncoding();
    System.out.println(ret); // UTF8
}

final var sjis = Charset.forName("Shift_JIS");

try (final var writer = new OutputStreamWriter(new ByteArrayOutputStream(), sjis)) {
    final var ret = writer.getEncoding();
    System.out.println(ret); // SJIS
}

void write (char[] cbuf, int off, int len)

Writes a portion of an array of characters.

final char[] cbuf = {'a', 'b', 'c', 'd'};

{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(cbuf, 0, 1);
    }
    System.out.println(os); // a
}
{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(cbuf, 0, 2);
    }
    System.out.println(os); // ab
}
{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(cbuf, 0, 3);
    }
    System.out.println(os); // abc
}
{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(cbuf, 0, 4);
    }
    System.out.println(os); // abcd
}
{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        //writer.write(cbuf, 0, 5); // IndexOutOfBoundsException
    }
}

final char[] cbuf = {'a', 'b', 'c', 'd'};

{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(cbuf, 0, 4);
    }
    System.out.println(os); // abcd
}
{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(cbuf, 1, 3);
    }
    System.out.println(os); // bcd
}
{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(cbuf, 2, 2);
    }
    System.out.println(os); // cd
}
{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(cbuf, 3, 1);
    }
    System.out.println(os); // d
}

void write (int c)

Writes a single character.

final var os = new ByteArrayOutputStream();

try (final var writer = new OutputStreamWriter(os)) {
    writer.write('a');
    writer.write('b');
    writer.write('c');
}

System.out.println(os); // abc

void write (String str, int off, int len)

Writes a portion of a string.

final var str = "abcd";

{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(str, 0, 1);
    }
    System.out.println(os); // a
}
{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(str, 0, 2);
    }
    System.out.println(os); // ab
}
{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(str, 0, 3);
    }
    System.out.println(os); // abc
}
{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(str, 0, 4);
    }
    System.out.println(os); // abcd
}
{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        //writer.write(str, 0, 5); // IndexOutOfBoundsException
    }
}

final var str = "abcd";

{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(str, 0, 4);
    }
    System.out.println(os); // abcd
}
{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(str, 1, 3);
    }
    System.out.println(os); // bcd
}
{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(str, 2, 2);
    }
    System.out.println(os); // cd
}
{
    final var os = new ByteArrayOutputStream();
    try (final var writer = new OutputStreamWriter(os)) {
        writer.write(str, 3, 1);
    }
    System.out.println(os); // d
}

Methods declared in Writer

append, append, append, nullWriter, write, write

Please see the link below.

Writer with Examples

API Examples

Java : OutputStreamWriter with Examples

Summary

Fields declared in Writer

lock

Constructors

OutputStreamWriter (OutputStream out)

OutputStreamWriter (OutputStream out, String charsetName)

OutputStreamWriter (OutputStream out, Charset cs)

OutputStreamWriter (OutputStream out, CharsetEncoder enc)

Methods

void close ()

void flush ()

String getEncoding ()

void write (char[] cbuf, int off, int len)

void write (int c)

void write (String str, int off, int len)

Methods declared in Writer

append, append, append, nullWriter, write, write

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