Java : CharBuffer - API使用例

CharBuffer (Java SE 22 & JDK 22) の使い方まとめです。
ほとんどのメソッドにサンプルコードがあります。
APIドキュメントのおともにどうぞ。

概要

charバッファです。

クラス構成

CharBuffer クラスは、プリミティブ型の char を扱う Buffer の実装です。

配列と違い、

容量(capacity) : バッファのサイズ。配列の length に相当
リミット(limit) : どの位置まで読み書き可能にするか
位置(position) : 次に読み書きする位置

という３つのプロパティを持ちます。

final var buffer = CharBuffer.allocate(5);

System.out.println(buffer.capacity()); // 5
System.out.println(buffer.limit()); // 5
System.out.println(buffer.position()); // 0

buffer.put('a');
System.out.println(buffer.position()); // 1

buffer.put('b');
System.out.println(buffer.position()); // 2

buffer.put('c');
System.out.println(buffer.position()); // 3

if (buffer.hasArray()) {
    final var ret = buffer.array();
    System.out.println(Arrays.toString(ret)); // [a, b, c,  ,  ]
}

final char[] array = {'a', 'b', 'c'};
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.capacity()); // 3
System.out.println(buffer.limit()); // 3
System.out.println(buffer.position()); // 0

System.out.println(buffer.get()); // a
System.out.println(buffer.position()); // 1

System.out.println(buffer.get()); // b
System.out.println(buffer.position()); // 2

System.out.println(buffer.get()); // c
System.out.println(buffer.position()); // 3

メソッド

static CharBuffer allocate (int capacity)

新しいcharバッファを割り当てます。

final var buffer = CharBuffer.allocate(5);

System.out.println(buffer.capacity()); // 5
System.out.println(buffer.limit()); // 5
System.out.println(buffer.position()); // 0

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [ ,  ,  ,  ,  ]
}

CharBuffer append (char c)

指定されたcharをこのバッファに追加します (オプションの操作)。

final var buffer = CharBuffer.allocate(3);

System.out.println(buffer.capacity()); // 3
System.out.println(buffer.position()); // 0

final var ret1 = buffer.append('a');
System.out.println(ret1.position()); // 1

final var ret2 = buffer.append('b');
System.out.println(ret2.position()); // 2

final var ret3 = buffer.append('c');
System.out.println(ret3.position()); // 3

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [a, b, c]
}

CharBuffer append (CharSequence csq)

指定されたcharシーケンスをこのバッファに追加します (オプションの操作)。

final var buffer = CharBuffer.allocate(6);

System.out.println(buffer.capacity()); // 6
System.out.println(buffer.position()); // 0

final var ret1 = buffer.append("a");
System.out.println(ret1.position()); // 1

final var ret2 = buffer.append("bc");
System.out.println(ret2.position()); // 3

final var ret3 = buffer.append("XYZ");
System.out.println(ret3.position()); // 6

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [a, b, c, X, Y, Z]
}

CharBuffer append (CharSequence csq, int start, int end)

指定されたcharシーケンスのサブシーケンスをこのバッファに追加します (オプションの操作)。

final var array = new char[6];
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.capacity()); // 6
System.out.println(buffer.position()); // 0

final var csq = "abcXYZ";

final var ret1 = buffer.append(csq, 0, 1);
System.out.println(ret1.position()); // 1
System.out.println(Arrays.toString(array)); // [a,  ,  ,  ,  ,  ]

final var ret2 = buffer.append(csq, 1, 3);
System.out.println(ret2.position()); // 3
System.out.println(Arrays.toString(array)); // [a, b, c,  ,  ,  ]

final var ret3 = buffer.append(csq, 3, 6);
System.out.println(ret3.position()); // 6
System.out.println(Arrays.toString(array)); // [a, b, c, X, Y, Z]

final char[] array ()

このバッファを補助するchar配列を返します (オプションの操作)。

final var buffer = CharBuffer.allocate(5)
        .put('a')
        .put('b')
        .put('c');

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [a, b, c,  ,  ]
}

final int arrayOffset ()

このバッファの補助配列内にある、このバッファの最初の要素のオフセットを返します (オプションの操作)。

final char[] array = {'a', 'b', 'c', 'd', 'e'};
final var buffer = CharBuffer.wrap(array);

final var sliced = buffer.slice(2, 3);

System.out.println(buffer); // abcde
if (buffer.hasArray()) {
    System.out.println(buffer.arrayOffset()); // 0
    System.out.println(buffer.get()); // a
    System.out.println(buffer.get()); // b
    System.out.println(buffer.get()); // c
    System.out.println(buffer.get()); // d
    System.out.println(buffer.get()); // e
}

System.out.println(sliced); // cde
if (sliced.hasArray()) {
    System.out.println(sliced.arrayOffset()); // 2
    System.out.println(sliced.get()); // c
    System.out.println(sliced.get()); // d
    System.out.println(sliced.get()); // e
}

abstract CharBuffer asReadOnlyBuffer ()

このバッファの内容を共有する新しい読込み専用charバッファを作成します。

final var buffer = CharBuffer.allocate(3);
buffer.put('a');

final var readOnlyBuffer = buffer.asReadOnlyBuffer();

System.out.println(buffer.position()); // 1
System.out.println(readOnlyBuffer.position()); // 1

readOnlyBuffer.clear();
System.out.println(readOnlyBuffer.get()); // a
System.out.println(readOnlyBuffer.get() == '\0'); // true
System.out.println(readOnlyBuffer.get() == '\0'); // true

buffer.put('b');

readOnlyBuffer.clear();
System.out.println(readOnlyBuffer.get()); // a
System.out.println(readOnlyBuffer.get()); // b
System.out.println(readOnlyBuffer.get() == '\0'); // true

try {
    var _ = readOnlyBuffer.put('c');
} catch (ReadOnlyBufferException e) {
    System.out.println("ReadOnlyBufferException!");
}

// 結果
// ↓
//ReadOnlyBufferException!

final char charAt (int index)

現在位置からの相対位置として指定されたインデックス位置にあるcharを読み込みます。

final var buffer = CharBuffer.wrap("abcXYZ");

System.out.println(buffer.capacity()); // 6
System.out.println(buffer.position()); // 0

System.out.println(buffer.charAt(0)); // a
System.out.println(buffer.charAt(1)); // b
System.out.println(buffer.charAt(2)); // c
System.out.println(buffer.charAt(3)); // X
System.out.println(buffer.charAt(4)); // Y
System.out.println(buffer.charAt(5)); // Z

System.out.println(buffer.position()); // 0
buffer.position(3);

System.out.println(buffer.charAt(0)); // X
System.out.println(buffer.charAt(1)); // Y
System.out.println(buffer.charAt(2)); // Z

System.out.println(buffer.position()); // 3

final CharBuffer clear ()

このバッファをクリアします。

final char[] array = {'a', 'b', 'c', 'd', 'e'};
final var buffer = CharBuffer.wrap(array);

buffer.limit(4);
buffer.position(2);

System.out.println(buffer.capacity()); // 5
System.out.println(buffer.limit()); // 4
System.out.println(buffer.position()); // 2

System.out.println(buffer.get()); // c
System.out.println(buffer.get()); // d
System.out.println(buffer.hasRemaining()); // false

final var ret = buffer.clear();
System.out.println(ret.capacity()); // 5
System.out.println(ret.limit()); // 5
System.out.println(ret.position()); // 0

System.out.println(buffer.get()); // a
System.out.println(buffer.get()); // b
System.out.println(buffer.get()); // c
System.out.println(buffer.get()); // d
System.out.println(buffer.get()); // e
System.out.println(buffer.hasRemaining()); // false

abstract CharBuffer compact ()

このバッファを圧縮します (オプションの操作)。

final char[] array = {'a', 'b', 'c', 'X', 'Y', 'Z'};
final var buffer = CharBuffer.wrap(array);

buffer.position(3);

final var ret = buffer.compact();
System.out.println(ret.position()); // 3

System.out.println(Arrays.toString(array)); // [X, Y, Z, X, Y, Z]

final char[] array = {'a', 'b', 'c', 'X', 'Y', 'Z'};
final var buffer = CharBuffer.wrap(array);

buffer.position(2);

final var ret = buffer.compact();
System.out.println(ret.position()); // 4

System.out.println(Arrays.toString(array)); // [c, X, Y, Z, Y, Z]

final char[] array = {'a', 'b', 'c', 'X', 'Y', 'Z'};
final var buffer = CharBuffer.wrap(array);

buffer.position(4);

final var ret = buffer.compact();
System.out.println(ret.position()); // 2

System.out.println(Arrays.toString(array)); // [Y, Z, c, X, Y, Z]

int compareTo (CharBuffer that)

このバッファを別のバッファと比較します。

final var buffer1 = CharBuffer.allocate(3)
        .put('a')
        .put('b')
        .put('c');

final var buffer2 = CharBuffer.allocate(3)
        .put('a')
        .put('b')
        .put('c');

buffer1.clear();
buffer2.clear();

System.out.println(buffer1.compareTo(buffer2)); // 0

final var buffer1 = CharBuffer.allocate(3)
        .put('b')
        .put('c')
        .put('d');

final var buffer2 = CharBuffer.allocate(3)
        .put('a')
        .put('x')
        .put('y');

final var buffer3 = CharBuffer.allocate(3)
        .put('d')
        .put('c')
        .put('b');

buffer1.clear();
buffer2.clear();
buffer3.clear();

System.out.println(buffer1.compareTo(buffer2)); // 1
System.out.println(buffer1.compareTo(buffer3)); // -2

abstract CharBuffer duplicate ()

このバッファの内容を共有する新しいcharバッファを作成します。

final char[] array = {'a', 'b', 'c', 'd', 'e'};
final var buffer = CharBuffer.wrap(array);

buffer.limit(4);
buffer.position(1);

final var duplicated = buffer.duplicate();

System.out.println(buffer.capacity()); // 5
System.out.println(buffer.limit()); // 4
System.out.println(buffer.position()); // 1

System.out.println(duplicated.capacity()); // 5
System.out.println(duplicated.limit()); // 4
System.out.println(duplicated.position()); // 1

System.out.println(buffer.get()); // b
System.out.println(buffer.get()); // c
System.out.println(buffer.get()); // d

System.out.println(duplicated.get()); // b
System.out.println(duplicated.get()); // c
System.out.println(duplicated.get()); // d

boolean equals (Object ob)

このバッファが別のオブジェクトと等価であるかどうかを判断します。

final var buffer1 = CharBuffer.allocate(3)
        .put('a')
        .put('b')
        .put('c');

final var buffer2 = CharBuffer.allocate(3)
        .put('a')
        .put('b')
        .put('c');

buffer1.clear();
buffer2.clear();

System.out.println(buffer1.equals(buffer2)); // true

final var buffer1 = CharBuffer.allocate(3)
        .put('b')
        .put('c')
        .put('d');

final var buffer2 = CharBuffer.allocate(3)
        .put('a')
        .put('x')
        .put('y');

final var buffer3 = CharBuffer.allocate(3)
        .put('d')
        .put('c')
        .put('b');

buffer1.clear();
buffer2.clear();
buffer3.clear();

System.out.println(buffer1.equals(buffer2)); // false
System.out.println(buffer1.equals(buffer3)); // false

final CharBuffer flip ()

このバッファをフリップ(反転)します。

final char[] array = {'a', 'b', 'c', 'd', 'e'};
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.capacity()); // 5
System.out.println(buffer.limit()); // 5
System.out.println(buffer.position()); // 0

System.out.println(buffer.get()); // a
System.out.println(buffer.get()); // b
System.out.println(buffer.get()); // c

System.out.println(buffer.limit()); // 5
System.out.println(buffer.position()); // 3

final var ret = buffer.flip();
System.out.println(ret.limit()); // 3
System.out.println(ret.position()); // 0

System.out.println(buffer.get()); // a
System.out.println(buffer.get()); // b
System.out.println(buffer.get()); // c

abstract char get ()

相対getメソッドです。

final char[] array = {'a', 'b', 'c'};
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.capacity()); // 3
System.out.println(buffer.position()); // 0

System.out.println(buffer.get()); // a
System.out.println(buffer.get()); // b
System.out.println(buffer.get()); // c

System.out.println(buffer.position()); // 3

CharBuffer get (char[] dst)

相対一括getメソッドです。

final char[] array = {'a', 'b', 'c', 'd', 'e', 'f', 'g'};
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.capacity()); // 7
System.out.println(buffer.position()); // 0

{
    final var dst = new char[3];
    System.out.println(Arrays.toString(dst)); // [ ,  ,  ]

    final var ret = buffer.get(dst);
    System.out.println(ret.position()); // 3

    System.out.println(Arrays.toString(dst)); // [a, b, c]
}
{
    final var dst = new char[3];
    System.out.println(Arrays.toString(dst)); // [ ,  ,  ]

    final var ret = buffer.get(dst);
    System.out.println(ret.position()); // 6

    System.out.println(Arrays.toString(dst)); // [d, e, f]
}

try {
    final var dst = new char[3];
    var _ = buffer.get(dst);
} catch (BufferUnderflowException e) {
    System.out.println("BufferUnderflowException!");
}

// 結果
// ↓
//BufferUnderflowException!

CharBuffer get (char[] dst, int offset, int length)

相対一括getメソッドです。

final char[] array = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'};
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.capacity()); // 8
System.out.println(buffer.position()); // 0

{
    final var dst = new char[5];
    System.out.println(Arrays.toString(dst)); // [ ,  ,  ,  ,  ]

    final var ret = buffer.get(dst, 0, 3);
    System.out.println(ret.position()); // 3

    System.out.println(Arrays.toString(dst)); // [a, b, c,  ,  ]
}
{
    final var dst = new char[5];
    System.out.println(Arrays.toString(dst)); // [ ,  ,  ,  ,  ]

    final var ret = buffer.get(dst, 1, 3);
    System.out.println(ret.position()); // 6

    System.out.println(Arrays.toString(dst)); // [ , d, e, f,  ]
}
{
    final var dst = new char[5];
    System.out.println(Arrays.toString(dst)); // [ ,  ,  ,  ,  ]

    final var ret = buffer.get(dst, 3, 2);
    System.out.println(ret.position()); // 8

    System.out.println(Arrays.toString(dst)); // [ ,  ,  , g, h]
}

abstract char get (int index)

絶対getメソッドです。

final char[] array = {'a', 'b', 'c'};
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.capacity()); // 3
System.out.println(buffer.position()); // 0

System.out.println(buffer.get(0)); // a
System.out.println(buffer.get(1)); // b
System.out.println(buffer.get(2)); // c

System.out.println(buffer.position()); // 0

CharBuffer get (int index, char[] dst)

絶対一括getメソッド。

final char[] array = {'a', 'b', 'c', 'd', 'e'};
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.capacity()); // 5
System.out.println(buffer.position()); // 0

{
    final var dst = new char[3];
    System.out.println(Arrays.toString(dst)); // [ ,  ,  ]

    final var ret = buffer.get(0, dst);
    System.out.println(ret.position()); // 0

    System.out.println(Arrays.toString(dst)); // [a, b, c]
}
{
    final var dst = new char[3];
    System.out.println(Arrays.toString(dst)); // [ ,  ,  ]

    final var ret = buffer.get(1, dst);
    System.out.println(ret.position()); // 0

    System.out.println(Arrays.toString(dst)); // [b, c, d]
}
{
    final var dst = new char[3];
    System.out.println(Arrays.toString(dst)); // [ ,  ,  ]

    final var ret = buffer.get(2, dst);
    System.out.println(ret.position()); // 0

    System.out.println(Arrays.toString(dst)); // [c, d, e]
}

CharBuffer get (int index, char[] dst, int offset, int length)

絶対一括getメソッド。

final char[] array = {'a', 'b', 'c', 'd', 'e', 'f'};
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.capacity()); // 6
System.out.println(buffer.position()); // 0

{
    final var dst = new char[5];
    System.out.println(Arrays.toString(dst)); // [ ,  ,  ,  ,  ]

    final var ret = buffer.get(0, dst, 0, 3);
    System.out.println(ret.position()); // 0

    System.out.println(Arrays.toString(dst)); // [a, b, c,  ,  ]
}
{
    final var dst = new char[5];
    System.out.println(Arrays.toString(dst)); // [ ,  ,  ,  ,  ]

    final var ret = buffer.get(2, dst, 1, 3);
    System.out.println(ret.position()); // 0

    System.out.println(Arrays.toString(dst)); // [ , c, d, e,  ]
}
{
    final var dst = new char[5];
    System.out.println(Arrays.toString(dst)); // [ ,  ,  ,  ,  ]

    final var ret = buffer.get(4, dst, 3, 2);
    System.out.println(ret.position()); // 0

    System.out.println(Arrays.toString(dst)); // [ ,  ,  , e, f]
}

final boolean hasArray ()

このバッファがアクセス可能なchar配列に連動するかどうかを判断します。

final var buffer = CharBuffer.allocate(5)
        .put('a')
        .put('b')
        .put('c');

final var ret = buffer.hasArray();
System.out.println(ret); // true

if (ret) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [a, b, c,  ,  ]
}

final var buffer = CharBuffer.allocate(5)
        .put('a')
        .put('b')
        .put('c')
        .asReadOnlyBuffer();

System.out.println(buffer.hasArray()); // false
try {
    var _ = buffer.array();
} catch (UnsupportedOperationException e) {
    System.out.println("UnsupportedOperationException!");
}

// 結果
// ↓
//UnsupportedOperationException!

int hashCode ()

このバッファの現在のハッシュ・コードを返します。

final var buffer = CharBuffer.allocate(0);
System.out.println(buffer.hashCode()); // 1

final var buffer = CharBuffer.allocate(3)
        .put('a')
        .put('b')
        .put('c')
        .clear();

System.out.println(buffer.hashCode()); // 128065

final var buffer = CharBuffer.allocate(3)
        .put('X')
        .put('Y')
        .put('Z')
        .clear();

System.out.println(buffer.hashCode()); // 119128

abstract boolean isDirect ()

このcharバッファがダイレクト・バッファであるかどうかを判断します。

final var buffer = CharBuffer.allocate(5);
System.out.println(buffer.isDirect()); // false

final char[] array = {'a', 'b', 'c'};
final var buffer = CharBuffer.wrap(array);
System.out.println(buffer.isDirect()); // false

final var buffer = ByteBuffer.allocateDirect(12).asCharBuffer();
System.out.println(buffer.isDirect()); // true

final boolean isEmpty ()

この文字バッファが空の場合、trueを返します。

final char[] array = {'a', 'b', 'c', 'd'};
final var buffer = CharBuffer.wrap(array);

buffer.limit(3);

System.out.println(buffer.capacity()); // 4
System.out.println(buffer.limit()); // 3
System.out.println(buffer.position()); // 0

System.out.println(buffer.remaining()); // 3
System.out.println(buffer.length()); // 3
System.out.println(buffer.isEmpty()); // false

System.out.println(buffer.get()); // a
System.out.println(buffer.position()); // 1

System.out.println(buffer.remaining()); // 2
System.out.println(buffer.length()); // 2
System.out.println(buffer.isEmpty()); // false

System.out.println(buffer.get()); // b
System.out.println(buffer.position()); // 2

System.out.println(buffer.remaining()); // 1
System.out.println(buffer.length()); // 1
System.out.println(buffer.isEmpty()); // false

System.out.println(buffer.get()); // c
System.out.println(buffer.position()); // 3

System.out.println(buffer.remaining()); // 0
System.out.println(buffer.length()); // 0
System.out.println(buffer.isEmpty()); // true

final int length ()

このcharバッファのバッファ長を返します。

final char[] array = {'a', 'b', 'c', 'd'};
final var buffer = CharBuffer.wrap(array);

buffer.limit(3);

System.out.println(buffer.capacity()); // 4
System.out.println(buffer.limit()); // 3
System.out.println(buffer.position()); // 0

System.out.println(buffer.remaining()); // 3
System.out.println(buffer.length()); // 3
System.out.println(buffer.isEmpty()); // false

System.out.println(buffer.get()); // a
System.out.println(buffer.position()); // 1

System.out.println(buffer.remaining()); // 2
System.out.println(buffer.length()); // 2
System.out.println(buffer.isEmpty()); // false

System.out.println(buffer.get()); // b
System.out.println(buffer.position()); // 2

System.out.println(buffer.remaining()); // 1
System.out.println(buffer.length()); // 1
System.out.println(buffer.isEmpty()); // false

System.out.println(buffer.get()); // c
System.out.println(buffer.position()); // 3

System.out.println(buffer.remaining()); // 0
System.out.println(buffer.length()); // 0
System.out.println(buffer.isEmpty()); // true

final CharBuffer limit (int newLimit)

このバッファのリミットを設定します。

final char[] array = {'a', 'b', 'c', 'd', 'e'};
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.position()); // 0
System.out.println(buffer.limit()); // 5

buffer.limit(3);

System.out.println(buffer.position()); // 0
System.out.println(buffer.limit()); // 3

buffer.clear();

System.out.println(buffer.position()); // 0
System.out.println(buffer.limit()); // 5

final char[] array = {'a', 'b', 'c', 'd', 'e'};
final var buffer = CharBuffer.wrap(array);

final var ret1 = buffer.limit(3);
System.out.println(ret1.limit()); // 3

System.out.println(buffer.get()); // a
System.out.println(buffer.get()); // b
System.out.println(buffer.get()); // c

try {
    var _ = buffer.get();
} catch (BufferUnderflowException e) {
    System.out.println("BufferUnderflowException!");
}

// 結果
// ↓
//BufferUnderflowException!

final CharBuffer mark ()

このバッファの現在位置にマークを設定します。

final char[] array = {'a', 'b', 'c', 'd', 'e'};
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.get()); // a
System.out.println(buffer.get()); // b

System.out.println(buffer.position()); // 2

final var ret1 = buffer.mark();
System.out.println(ret1.position()); // 2

System.out.println(buffer.get()); // c
System.out.println(buffer.get()); // d
System.out.println(buffer.get()); // e

System.out.println(buffer.position()); // 5

final var ret2 = buffer.reset();
System.out.println(ret2.position()); // 2

System.out.println(buffer.get()); // c
System.out.println(buffer.get()); // d
System.out.println(buffer.get()); // e

int mismatch (CharBuffer that)

このバッファと指定されたバッファの最初の不一致の相対索引を検索して戻します。

final char[] array = {'a', 'b', 'c', 'd'};
final var buffer = CharBuffer.wrap(array);

{
    final char[] a = {'a'};
    final var that = CharBuffer.wrap(a);

    System.out.println(buffer.mismatch(that)); // 1
}
{
    final char[] a = {'a', 'b'};
    final var that = CharBuffer.wrap(a);

    System.out.println(buffer.mismatch(that)); // 2
}
{
    final char[] a = {'a', 'b', 'c'};
    final var that = CharBuffer.wrap(a);

    System.out.println(buffer.mismatch(that)); // 3
}
{
    final char[] a = {'a', 'b', 'c', 'd'};
    final var that = CharBuffer.wrap(a);

    System.out.println(buffer.mismatch(that)); // -1
}
{
    final char[] a = {'a', 'b', 'c', 'd', 'e'};
    final var that = CharBuffer.wrap(a);

    System.out.println(buffer.mismatch(that)); // 4
}
{
    final char[] a = {'a', 'b', 'X'};
    final var that = CharBuffer.wrap(a); // 2

    System.out.println(buffer.mismatch(that));
}
{
    final char[] a = {'Y', 'Z'};
    final var that = CharBuffer.wrap(a);

    System.out.println(buffer.mismatch(that)); // 0
}

abstract ByteOrder order ()

このバッファのbyte順序を取得します。

final var os = System.getProperty("os.name");
System.out.println(os); // Windows 10

final var buffer = CharBuffer.allocate(5);
System.out.println(buffer.order()); // LITTLE_ENDIAN

final CharBuffer position (int newPosition)

このバッファの位置を設定します。

final char[] array = {'a', 'b', 'c', 'd', 'e'};
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.position()); // 0

System.out.println(buffer.get()); // a
System.out.println(buffer.position()); // 1

System.out.println(buffer.get()); // b
System.out.println(buffer.position()); // 2

System.out.println(buffer.get()); // c
System.out.println(buffer.position()); // 3

System.out.println(buffer.get()); // d
System.out.println(buffer.position()); // 4

System.out.println(buffer.get()); // e
System.out.println(buffer.position()); // 5

final var ret = buffer.position(3);
System.out.println(ret.position()); // 3

System.out.println(buffer.get()); // d
System.out.println(buffer.position()); // 4

System.out.println(buffer.get()); // e
System.out.println(buffer.position()); // 5

abstract CharBuffer put (char c)

相対putメソッドです (オプションの操作)。

final var buffer = CharBuffer.allocate(3);

System.out.println(buffer.capacity()); // 3
System.out.println(buffer.position()); // 0

final var ret1 = buffer.put('a');
System.out.println(ret1.position()); // 1

final var ret2 = buffer.put('b');
System.out.println(ret2.position()); // 2

final var ret3 = buffer.put('c');
System.out.println(ret3.position()); // 3

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [a, b, c]
}

final CharBuffer put (char[] src)

相対一括putメソッドです (オプションの操作)。

final var buffer = CharBuffer.allocate(6);

System.out.println(buffer.capacity()); // 6
System.out.println(buffer.position()); // 0

{
    final char[] src = {'a'};

    final var ret = buffer.put(src);
    System.out.println(ret.position()); // 1
}
{
    final char[] src = {'b', 'c'};

    final var ret = buffer.put(src);
    System.out.println(ret.position()); // 3
}
{
    final char[] src = {'d', 'e', 'f'};

    final var ret = buffer.put(src);
    System.out.println(ret.position()); // 6
}

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [a, b, c, d, e, f]
}

CharBuffer put (char[] src, int offset, int length)

相対一括putメソッドです (オプションの操作)。

final var array = new char[6];
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.capacity()); // 6
System.out.println(buffer.position()); // 0

final char[] src = {'a', 'b', 'c', 'd', 'e', 'f'};

final var ret1 = buffer.put(src, 0, 1);
System.out.println(ret1.position()); // 1
System.out.println(Arrays.toString(array)); // [a,  ,  ,  ,  ,  ]

final var ret2 = buffer.put(src, 1, 2);
System.out.println(ret2.position()); // 3
System.out.println(Arrays.toString(array)); // [a, b, c,  ,  ,  ]

final var ret3 = buffer.put(src, 3, 3);
System.out.println(ret3.position()); // 6
System.out.println(Arrays.toString(array)); // [a, b, c, d, e, f]

abstract CharBuffer put (int index, char c)

絶対putメソッドです (オプションの操作)。

final var buffer = CharBuffer.allocate(3);

System.out.println(buffer.capacity()); // 3
System.out.println(buffer.position()); // 0

final var ret1 = buffer.put(0, 'a');
System.out.println(ret1.position()); // 0

final var ret2 = buffer.put(1, 'b');
System.out.println(ret2.position()); // 0

final var ret3 = buffer.put(2, 'c');
System.out.println(ret3.position()); // 0

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [a, b, c]
}

CharBuffer put (int index, char[] src)

(optional operation)の絶対一括putメソッド。

final var buffer = CharBuffer.allocate(6);

System.out.println(buffer.capacity()); // 6
System.out.println(buffer.position()); // 0

{
    final char[] src = {'a'};

    final var ret = buffer.put(0, src);
    System.out.println(ret.position()); // 0
}
{
    final char[] src = {'b', 'c'};

    final var ret = buffer.put(1, src);
    System.out.println(ret.position()); // 0
}
{
    final char[] src = {'d', 'e', 'f'};

    final var ret = buffer.put(3, src);
    System.out.println(ret.position()); // 0
}

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [a, b, c, d, e, f]
}

CharBuffer put (int index, char[] src, int offset, int length)

(optional operation)の絶対一括putメソッド。

final var array = new char[6];
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.capacity()); // 6
System.out.println(buffer.position()); // 0

final char[] src = {'a', 'b', 'c', 'd', 'e', 'f'};

final var ret1 = buffer.put(0, src, 0, 1);
System.out.println(ret1.position()); // 0
System.out.println(Arrays.toString(array)); // [a,  ,  ,  ,  ,  ]

final var ret2 = buffer.put(1, src, 1, 2);
System.out.println(ret2.position()); // 0
System.out.println(Arrays.toString(array)); // [a, b, c,  ,  ,  ]

final var ret3 = buffer.put(3, src, 3, 3);
System.out.println(ret3.position()); // 0
System.out.println(Arrays.toString(array)); // [a, b, c, d, e, f]

CharBuffer put (int index, CharBuffer src, int offset, int length)

(optional operation)の絶対一括putメソッド。

final var array = new char[6];
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.capacity()); // 6
System.out.println(buffer.position()); // 0

final char[] srcArray = {'a', 'b', 'c', 'd', 'e', 'f'};
final var src = CharBuffer.wrap(srcArray);

final var ret1 = buffer.put(0, src, 0, 1);
System.out.println(ret1.position()); // 0
System.out.println(Arrays.toString(array)); // [a,  ,  ,  ,  ,  ]

final var ret2 = buffer.put(1, src, 1, 2);
System.out.println(ret2.position()); // 0
System.out.println(Arrays.toString(array)); // [a, b, c,  ,  ,  ]

final var ret3 = buffer.put(3, src, 3, 3);
System.out.println(ret3.position()); // 0
System.out.println(Arrays.toString(array)); // [a, b, c, d, e, f]

final CharBuffer put (String src)

相対一括putメソッドです (オプションの操作)。

final var buffer = CharBuffer.allocate(6);

System.out.println(buffer.capacity()); // 6
System.out.println(buffer.position()); // 0

final var ret1 = buffer.put("a");
System.out.println(ret1.position()); // 1

final var ret2 = buffer.put("bc");
System.out.println(ret2.position()); // 3

final var ret3 = buffer.put("XYZ");
System.out.println(ret3.position()); // 6

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [a, b, c, X, Y, Z]
}

CharBuffer put (String src, int start, int end)

相対一括putメソッドです (オプションの操作)。

final var array = new char[6];
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.capacity()); // 6
System.out.println(buffer.position()); // 0

final var src = "abcXYZ";

final var ret1 = buffer.put(src, 0, 1);
System.out.println(ret1.position()); // 1
System.out.println(Arrays.toString(array)); // [a,  ,  ,  ,  ,  ]

final var ret2 = buffer.put(src, 1, 3);
System.out.println(ret2.position()); // 3
System.out.println(Arrays.toString(array)); // [a, b, c,  ,  ,  ]

final var ret3 = buffer.put(src, 3, 6);
System.out.println(ret3.position()); // 6
System.out.println(Arrays.toString(array)); // [a, b, c, X, Y, Z]

CharBuffer put (CharBuffer src)

相対一括putメソッドです (オプションの操作)。

final var buffer = CharBuffer.allocate(5);

System.out.println(buffer.capacity()); // 5
System.out.println(buffer.position()); // 0

{
    final char[] array = {'a', 'b'};
    final var src = CharBuffer.wrap(array);

    final var ret = buffer.put(src);
    System.out.println(ret.position()); // 2
}
{
    final char[] array = {'c', 'd', 'e'};
    final var src = CharBuffer.wrap(array);

    final var ret = buffer.put(src);
    System.out.println(ret.position()); // 5
}

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [a, b, c, d, e]
}

int read (CharBuffer target)

指定されたcharバッファにcharを読み込みます。

final var buffer = CharBuffer.wrap("abcde");

System.out.println(buffer.capacity()); // 5
System.out.println(buffer.position()); // 0

{
    final var array = new char[2];
    final var target = CharBuffer.wrap(array);

    System.out.println(buffer.read(target)); // 2
    System.out.println(buffer.position()); // 2
    System.out.println(Arrays.toString(array)); // [a, b]
}
{
    final var array = new char[3];
    final var target = CharBuffer.wrap(array);

    System.out.println(buffer.read(target)); // 3
    System.out.println(buffer.position()); // 5
    System.out.println(Arrays.toString(array)); // [c, d, e]
}

final CharBuffer reset ()

バッファの位置を以前にマークした位置に戻します。

final char[] array = {'a', 'b', 'c', 'd', 'e'};
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.get()); // a
System.out.println(buffer.get()); // b

System.out.println(buffer.position()); // 2

final var ret1 = buffer.mark();
System.out.println(ret1.position()); // 2

System.out.println(buffer.get()); // c
System.out.println(buffer.get()); // d
System.out.println(buffer.get()); // e

System.out.println(buffer.position()); // 5

final var ret2 = buffer.reset();
System.out.println(ret2.position()); // 2

System.out.println(buffer.get()); // c
System.out.println(buffer.get()); // d
System.out.println(buffer.get()); // e

final CharBuffer rewind ()

このバッファをリワインド(巻き戻し)します。

final char[] array = {'a', 'b', 'c', 'd', 'e'};
final var buffer = CharBuffer.wrap(array);

buffer.limit(4);
buffer.position(2);

System.out.println(buffer.limit()); // 4
System.out.println(buffer.position()); // 2

final var ret = buffer.rewind();
System.out.println(ret.limit()); // 4
System.out.println(ret.position()); // 0

abstract CharBuffer slice ()

このバッファの内容の共有のサブシーケンスを内容とする新しいcharバッファを作成します。

final char[] array = {'a', 'b', 'c', 'd', 'e'};
final var buffer = CharBuffer.wrap(array);

buffer.limit(4);
buffer.position(1);

final var sliced = buffer.slice();

System.out.println(buffer.capacity()); // 5
System.out.println(buffer.limit()); // 4
System.out.println(buffer.position()); // 1

System.out.println(sliced.capacity()); // 3
System.out.println(sliced.limit()); // 3
System.out.println(sliced.position()); // 0

System.out.println(buffer.get()); // b
System.out.println(buffer.get()); // c
System.out.println(buffer.get()); // d
System.out.println(buffer.hasRemaining()); // false

System.out.println(sliced.get()); // b
System.out.println(sliced.get()); // c
System.out.println(sliced.get()); // d
System.out.println(sliced.hasRemaining()); // false

abstract CharBuffer slice (int index, int length)

このバッファの内容の共有のサブシーケンスを内容とする新しいcharバッファを作成します。

final char[] array = {'a', 'b', 'c', 'd', 'e'};
final var buffer = CharBuffer.wrap(array);

final var sliced = buffer.slice(2, 3);

System.out.println(buffer.capacity()); // 5
System.out.println(buffer.limit()); // 5
System.out.println(buffer.position()); // 0

System.out.println(sliced.capacity()); // 3
System.out.println(sliced.limit()); // 3
System.out.println(sliced.position()); // 0

System.out.println(buffer.get()); // a
System.out.println(buffer.get()); // b
System.out.println(buffer.get()); // c
System.out.println(buffer.get()); // d
System.out.println(buffer.get()); // e
System.out.println(buffer.hasRemaining()); // false

System.out.println(sliced.get()); // c
System.out.println(sliced.get()); // d
System.out.println(sliced.get()); // e
System.out.println(sliced.hasRemaining()); // false

abstract CharBuffer subSequence (int start, int end)

このバッファの指定されたサブシーケンス(現在位置からの相対位置)を表す新しいcharバッファを作成します。

final char[] array = {'a', 'b', 'c', 'd', 'e'};
final var buffer = CharBuffer.wrap(array);

{
    final var ret = buffer.subSequence(0, 2);
    System.out.println(ret.capacity()); // 5
    System.out.println(ret.limit()); // 2
    System.out.println(ret.position()); // 0

    System.out.println(ret.get()); // a
    System.out.println(ret.get()); // b
    System.out.println(ret.hasRemaining()); // false
}

System.out.println(buffer.position()); // 0

{
    final var ret = buffer.subSequence(2, 5);
    System.out.println(ret.capacity()); // 5
    System.out.println(ret.limit()); // 5
    System.out.println(ret.position()); // 2

    System.out.println(ret.get()); // c
    System.out.println(ret.get()); // d
    System.out.println(ret.get()); // e
    System.out.println(ret.hasRemaining()); // false
}

System.out.println(buffer.position()); // 0

String toString ()

このバッファ内に残っているcharを含む文字列を返します。

final var buffer = CharBuffer.wrap("abcXYZ");
System.out.println(buffer.position()); // 0

final var str1 = buffer.toString();
System.out.println(str1); // abcXYZ

buffer.position(3);
System.out.println(buffer.position()); // 3

final var str2 = buffer.toString();
System.out.println(str2); // XYZ

static CharBuffer wrap (char[] array)

char配列をバッファにラップします。

final char[] array = {'a', 'b', 'c'};
final var buffer = CharBuffer.wrap(array);

System.out.println(buffer.capacity()); // 3
System.out.println(buffer.limit()); // 3
System.out.println(buffer.position()); // 0

if (buffer.hasArray()) {
    System.out.println(buffer.arrayOffset()); // 0

    System.out.println(buffer.get()); // a
    System.out.println(buffer.get()); // b
    System.out.println(buffer.get()); // c
}

static CharBuffer wrap (char[] array, int offset, int length)

char配列をバッファにラップします。

final char[] array = {'a', 'b', 'c', 'd', 'e', 'f', 'g'};
final var buffer = CharBuffer.wrap(array, 2, 4);

System.out.println(buffer.capacity()); // 7
System.out.println(buffer.limit()); // 6
System.out.println(buffer.position()); // 2

if (buffer.hasArray()) {
    System.out.println(buffer.arrayOffset()); // 0

    System.out.println(buffer.get()); // c
    System.out.println(buffer.get()); // d
    System.out.println(buffer.get()); // e
    System.out.println(buffer.get()); // f
}

static CharBuffer wrap (CharSequence csq)

charシーケンスをバッファにラップします。

final var buffer = CharBuffer.wrap("abc");

System.out.println(buffer.capacity()); // 3
System.out.println(buffer.limit()); // 3
System.out.println(buffer.position()); // 0

System.out.println(buffer.get()); // a
System.out.println(buffer.get()); // b
System.out.println(buffer.get()); // c

static CharBuffer wrap (CharSequence csq, int start, int end)

charシーケンスをバッファにラップします。

final var buffer = CharBuffer.wrap("abcdefg", 2, 6);

System.out.println(buffer.capacity()); // 7
System.out.println(buffer.limit()); // 6
System.out.println(buffer.position()); // 2

System.out.println(buffer.get()); // c
System.out.println(buffer.get()); // d
System.out.println(buffer.get()); // e
System.out.println(buffer.get()); // f

Bufferで宣言されたメソッド

capacity, hasRemaining, isReadOnly, limit, position, remaining

「Java API 使用例 : Buffer」をご参照ください。

CharSequenceで宣言されたメソッド

chars, codePoints

「Java API 使用例 : CharSequence」をご参照ください。

API 使用例
- Buffer

Java : CharBuffer - API使用例

概要

メソッド

static CharBuffer allocate (int capacity)

CharBuffer append (char c)

CharBuffer append (CharSequence csq)

CharBuffer append (CharSequence csq, int start, int end)

final char[] array ()

final int arrayOffset ()

abstract CharBuffer asReadOnlyBuffer ()

final char charAt (int index)

final CharBuffer clear ()

abstract CharBuffer compact ()

int compareTo (CharBuffer that)

abstract CharBuffer duplicate ()

boolean equals (Object ob)

final CharBuffer flip ()

abstract char get ()

CharBuffer get (char[] dst)

CharBuffer get (char[] dst, int offset, int length)

abstract char get (int index)

CharBuffer get (int index, char[] dst)

CharBuffer get (int index, char[] dst, int offset, int length)

final boolean hasArray ()

int hashCode ()

abstract boolean isDirect ()

final boolean isEmpty ()

final int length ()

final CharBuffer limit (int newLimit)

final CharBuffer mark ()

int mismatch (CharBuffer that)

abstract ByteOrder order ()

final CharBuffer position (int newPosition)

abstract CharBuffer put (char c)

final CharBuffer put (char[] src)

CharBuffer put (char[] src, int offset, int length)

abstract CharBuffer put (int index, char c)

CharBuffer put (int index, char[] src)

CharBuffer put (int index, char[] src, int offset, int length)

CharBuffer put (int index, CharBuffer src, int offset, int length)

final CharBuffer put (String src)

CharBuffer put (String src, int start, int end)

CharBuffer put (CharBuffer src)

int read (CharBuffer target)

final CharBuffer reset ()

final CharBuffer rewind ()

abstract CharBuffer slice ()

abstract CharBuffer slice (int index, int length)

abstract CharBuffer subSequence (int start, int end)

String toString ()

static CharBuffer wrap (char[] array)

static CharBuffer wrap (char[] array, int offset, int length)

static CharBuffer wrap (CharSequence csq)

static CharBuffer wrap (CharSequence csq, int start, int end)

Bufferで宣言されたメソッド

capacity, hasRemaining, isReadOnly, limit, position, remaining

CharSequenceで宣言されたメソッド

chars, codePoints

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