Java : FloatBuffer - API使用例

FloatBuffer (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

floatバッファです。

クラス構成

FloatBuffer クラスは、プリミティブ型の float 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 = FloatBuffer.allocate(5);

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

buffer.put(0.1f);
System.out.println(buffer.position()); // 1

buffer.put(0.2f);
System.out.println(buffer.position()); // 2

buffer.put(0.3f);
System.out.println(buffer.position()); // 3

if (buffer.hasArray()) {
    final var ret = buffer.array();
    System.out.println(Arrays.toString(ret)); // [0.1, 0.2, 0.3, 0.0, 0.0]
}

final float[] array = {0.1f, 0.2f, 0.3f};
final var buffer = FloatBuffer.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()); // 10
System.out.println(buffer.position()); // 0.1

System.out.println(buffer.get()); // 20
System.out.println(buffer.position()); // 0.2

System.out.println(buffer.get()); // 30
System.out.println(buffer.position()); // 0.3

メソッド

static FloatBuffer allocate (int capacity)

新しいfloatバッファを割り当てます。

final var buffer = FloatBuffer.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)); // [0.0, 0.0, 0.0, 0.0, 0.0]
}

final float[] array ()

このバッファを補助するfloat配列を返します (オプションの操作)。

final var buffer = FloatBuffer.allocate(5)
        .put(0.1f)
        .put(0.2f)
        .put(0.3f);

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [0.1, 0.2, 0.3, 0.0, 0.0]
}

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 float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

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

System.out.println(buffer); // java.nio.HeapFloatBuffer[pos=0 lim=5 cap=5]
if (buffer.hasArray()) {
    System.out.println(buffer.arrayOffset()); // 0
    System.out.println(buffer.get()); // 0.1
    System.out.println(buffer.get()); // 0.2
    System.out.println(buffer.get()); // 0.3
    System.out.println(buffer.get()); // 0.4
    System.out.println(buffer.get()); // 0.5
}

System.out.println(sliced); // java.nio.HeapFloatBuffer[pos=0 lim=3 cap=3]
if (sliced.hasArray()) {
    System.out.println(sliced.arrayOffset()); // 2
    System.out.println(sliced.get()); // 0.3
    System.out.println(sliced.get()); // 0.4
    System.out.println(sliced.get()); // 0.5
}

abstract FloatBuffer asReadOnlyBuffer ()

このバッファの内容を共有する新しい読込み専用floatバッファを作成します。

final var buffer = FloatBuffer.allocate(3);
buffer.put(0.1f);

final var readOnlyBuffer = buffer.asReadOnlyBuffer();

System.out.println(buffer); // java.nio.HeapFloatBuffer[pos=1 lim=3 cap=3]
System.out.println(readOnlyBuffer); // java.nio.HeapFloatBufferR[pos=1 lim=3 cap=3]

readOnlyBuffer.clear();
System.out.println(readOnlyBuffer.get()); // 0.1
System.out.println(readOnlyBuffer.get()); // 0.0
System.out.println(readOnlyBuffer.get()); // 0.0

buffer.put(0.2f);

readOnlyBuffer.clear();
System.out.println(readOnlyBuffer.get()); // 0.1
System.out.println(readOnlyBuffer.get()); // 0.2
System.out.println(readOnlyBuffer.get()); // 0.0

try {
    var _ = readOnlyBuffer.put(0.3f);
} catch (ReadOnlyBufferException e) {
    System.out.println("ReadOnlyBufferException!");
}

// 結果
// ↓
//ReadOnlyBufferException!

final FloatBuffer clear ()

このバッファをクリアします。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

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

System.out.println(buffer); // java.nio.HeapFloatBuffer[pos=2 lim=4 cap=5]

System.out.println(buffer.get()); // 0.3
System.out.println(buffer.get()); // 0.4
System.out.println(buffer.hasRemaining()); // false

System.out.println(buffer.clear()); // java.nio.HeapFloatBuffer[pos=0 lim=5 cap=5]

System.out.println(buffer.get()); // 0.1
System.out.println(buffer.get()); // 0.2
System.out.println(buffer.get()); // 0.3
System.out.println(buffer.get()); // 0.4
System.out.println(buffer.get()); // 0.5
System.out.println(buffer.hasRemaining()); // false

abstract FloatBuffer compact ()

このバッファを圧縮します (オプションの操作)。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f, 0.6f};
final var buffer = FloatBuffer.wrap(array);

buffer.position(3);
System.out.println(buffer.compact()); // java.nio.HeapFloatBuffer[pos=3 lim=6 cap=6]

System.out.println(Arrays.toString(array)); // [0.4, 0.5, 0.6, 0.4, 0.5, 0.6]

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f, 0.6f};
final var buffer = FloatBuffer.wrap(array);

buffer.position(2);
System.out.println(buffer.compact()); // java.nio.HeapFloatBuffer[pos=4 lim=6 cap=6]

System.out.println(Arrays.toString(array)); // [0.3, 0.4, 0.5, 0.6, 0.5, 0.6]

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f, 0.6f};
final var buffer = FloatBuffer.wrap(array);

buffer.position(4);
System.out.println(buffer.compact()); // java.nio.HeapFloatBuffer[pos=2 lim=6 cap=6]

System.out.println(Arrays.toString(array)); // [0.5, 0.6, 0.3, 0.4, 0.5, 0.6]

int compareTo (FloatBuffer that)

このバッファを別のバッファと比較します。

final var buffer1 = FloatBuffer.allocate(3)
        .put(0.1f)
        .put(0.2f)
        .put(0.3f);

final var buffer2 = FloatBuffer.allocate(3)
        .put(0.1f)
        .put(0.2f)
        .put(0.3f);

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

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

final var buffer1 = FloatBuffer.allocate(3)
        .put(10.0f)
        .put(20.0f)
        .put(30.0f);

final var buffer2 = FloatBuffer.allocate(3)
        .put(5.0f)
        .put(50.0f)
        .put(500.0f);

final var buffer3 = FloatBuffer.allocate(3)
        .put(30.0f)
        .put(20.0f)
        .put(10.0f);

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

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

abstract FloatBuffer duplicate ()

このバッファの内容を共有する新しいfloatバッファを作成します。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

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

final var duplicated = buffer.duplicate();

System.out.println(buffer); // java.nio.HeapFloatBuffer[pos=1 lim=4 cap=5]
System.out.println(duplicated); // java.nio.HeapFloatBuffer[pos=1 lim=4 cap=5]

System.out.println(buffer.get()); // 0.2
System.out.println(buffer.get()); // 0.3
System.out.println(buffer.get()); // 0.4

System.out.println(duplicated.get()); // 0.2
System.out.println(duplicated.get()); // 0.3
System.out.println(duplicated.get()); // 0.4

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 = FloatBuffer.allocate(3)
        .put(0.1f)
        .put(0.2f)
        .put(0.3f);

final var buffer2 = FloatBuffer.allocate(3)
        .put(0.1f)
        .put(0.2f)
        .put(0.3f);

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

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

final var buffer1 = FloatBuffer.allocate(3)
        .put(10.0f)
        .put(20.0f)
        .put(30.0f);

final var buffer2 = FloatBuffer.allocate(3)
        .put(5.0f)
        .put(50.0f)
        .put(500.0f);

final var buffer3 = FloatBuffer.allocate(3)
        .put(30.0f)
        .put(20.0f)
        .put(10.0f);

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

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

final FloatBuffer flip ()

このバッファをフリップ(反転)します。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

System.out.println(buffer.get()); // 0.1
System.out.println(buffer.get()); // 0.2
System.out.println(buffer.get()); // 0.3

System.out.println(buffer); // java.nio.HeapFloatBuffer[pos=3 lim=5 cap=5]
System.out.println(buffer.flip()); // java.nio.HeapFloatBuffer[pos=0 lim=3 cap=5]

System.out.println(buffer.get()); // 0.1
System.out.println(buffer.get()); // 0.2
System.out.println(buffer.get()); // 0.3

abstract float get ()

相対getメソッドです。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

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

System.out.println(buffer.get()); // 0.1
System.out.println(buffer.get()); // 0.2
System.out.println(buffer.get()); // 0.3
System.out.println(buffer.get()); // 0.4
System.out.println(buffer.get()); // 0.5

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

FloatBuffer get (float[] dst)

相対一括getメソッドです。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f, 0.6f, 0.7f};
final var buffer = FloatBuffer.wrap(array);

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

{
    final var dst = new float[3];
    System.out.println(Arrays.toString(dst)); // [0.0, 0.0, 0.0]

    final var ret = buffer.get(dst);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=3 lim=7 cap=7]

    System.out.println(Arrays.toString(dst)); // [0.1, 0.2, 0.3]
    System.out.println(buffer.position()); // 3
}
{
    final var dst = new float[3];
    System.out.println(Arrays.toString(dst)); // [0.0, 0.0, 0.0]

    final var ret = buffer.get(dst);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=6 lim=7 cap=7]

    System.out.println(Arrays.toString(dst)); // [0.4, 0.5, 0.6]
    System.out.println(buffer.position()); // 6
}

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

// 結果
// ↓
//BufferUnderflowException!

FloatBuffer get (float[] dst, int offset, int length)

相対一括getメソッドです。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f, 0.6f, 0.7f, 0.8f};
final var buffer = FloatBuffer.wrap(array);

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

{
    final var dst = new float[5];
    System.out.println(Arrays.toString(dst)); // [0.0, 0.0, 0.0, 0.0, 0.0]

    final var ret = buffer.get(dst, 0, 3);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=3 lim=8 cap=8]

    System.out.println(Arrays.toString(dst)); // [0.1, 0.2, 0.3, 0.0, 0.0]
    System.out.println(buffer.position()); // 3
}
{
    final var dst = new float[5];
    System.out.println(Arrays.toString(dst)); // [0.0, 0.0, 0.0, 0.0, 0.0]

    final var ret = buffer.get(dst, 1, 3);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=6 lim=8 cap=8]

    System.out.println(Arrays.toString(dst)); // [0.0, 0.4, 0.5, 0.6, 0.0]
    System.out.println(buffer.position()); // 6
}
{
    final var dst = new float[5];
    System.out.println(Arrays.toString(dst)); // [0.0, 0.0, 0.0, 0.0, 0.0]

    final var ret = buffer.get(dst, 3, 2);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=8 lim=8 cap=8]

    System.out.println(Arrays.toString(dst)); // [0.0, 0.0, 0.0, 0.7, 0.8]
    System.out.println(buffer.position()); // 8
}

abstract float get (int index)

絶対getメソッドです。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

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

System.out.println(buffer.get(0)); // 0.1
System.out.println(buffer.get(1)); // 0.2
System.out.println(buffer.get(2)); // 0.3
System.out.println(buffer.get(3)); // 0.4
System.out.println(buffer.get(4)); // 0.5

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

FloatBuffer get (int index, float[] dst)

絶対一括getメソッド。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

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

{
    final var dst = new float[3];
    System.out.println(Arrays.toString(dst)); // [0.0, 0.0, 0.0]

    final var ret = buffer.get(0, dst);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=0 lim=5 cap=5]

    System.out.println(Arrays.toString(dst)); // [0.1, 0.2, 0.3]
    System.out.println(buffer.position()); // 0
}
{
    final var dst = new float[3];
    System.out.println(Arrays.toString(dst)); // [0.0, 0.0, 0.0]

    final var ret = buffer.get(1, dst);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=0 lim=5 cap=5]

    System.out.println(Arrays.toString(dst)); // [0.2, 0.3, 0.4]
    System.out.println(buffer.position()); // 0
}
{
    final var dst = new float[3];
    System.out.println(Arrays.toString(dst)); // [0.0, 0.0, 0.0]

    final var ret = buffer.get(2, dst);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=0 lim=5 cap=5]

    System.out.println(Arrays.toString(dst)); // [0.3, 0.4, 0.5]
    System.out.println(buffer.position()); // 0
}

FloatBuffer get (int index, float[] dst, int offset, int length)

絶対一括getメソッド。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f, 0.6f};
final var buffer = FloatBuffer.wrap(array);

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

{
    final var dst = new float[5];
    System.out.println(Arrays.toString(dst)); // [0.0, 0.0, 0.0, 0.0, 0.0]

    final var ret = buffer.get(0, dst, 0, 3);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=0 lim=6 cap=6]

    System.out.println(Arrays.toString(dst)); // [0.1, 0.2, 0.3, 0.0, 0.0]
    System.out.println(buffer.position()); // 0
}
{
    final var dst = new float[5];
    System.out.println(Arrays.toString(dst)); // [0.0, 0.0, 0.0, 0.0, 0.0]

    final var ret = buffer.get(2, dst, 1, 3);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=0 lim=6 cap=6]

    System.out.println(Arrays.toString(dst)); // [0.0, 0.3, 0.4, 0.5, 0.0]
    System.out.println(buffer.position()); // 0
}
{
    final var dst = new float[5];
    System.out.println(Arrays.toString(dst)); // [0.0, 0.0, 0.0, 0.0, 0.0]

    final var ret = buffer.get(4, dst, 3, 2);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=0 lim=6 cap=6]

    System.out.println(Arrays.toString(dst)); // [0.0, 0.0, 0.0, 0.5, 0.6]
    System.out.println(buffer.position()); // 0
}

final boolean hasArray ()

このバッファがアクセス可能なfloat配列に連動するかどうかを判断します。

final var buffer = FloatBuffer.allocate(5)
        .put(0.1f)
        .put(0.2f)
        .put(0.3f);

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

if (ret) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [0.1, 0.2, 0.3, 0.0, 0.0]
}

final var buffer = FloatBuffer.allocate(5)
        .put(0.1f)
        .put(0.2f)
        .put(0.3f)
        .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 = FloatBuffer.allocate(0);
System.out.println(buffer.hashCode()); // 1

final var buffer = FloatBuffer.allocate(3)
        .put(0.1f)
        .put(0.2f)
        .put(0.3f)
        .clear();

System.out.println(buffer.hashCode()); // 29791

final var buffer = FloatBuffer.allocate(3)
        .put(-123.0f)
        .put(-456.0f)
        .put(-789.0f)
        .clear();

System.out.println(buffer.hashCode()); // -742697

abstract boolean isDirect ()

現在のfloat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 = FloatBuffer.allocate(5);
System.out.println(buffer.isDirect()); // false

final float[] array = {0.1f, 0.2f, 0.3f};
final var buffer = FloatBuffer.wrap(array);
System.out.println(buffer.isDirect()); // false

final var buffer = ByteBuffer.allocateDirect(8).asFloatBuffer();
System.out.println(buffer.isDirect()); // true

final FloatBuffer limit (int newLimit)

このバッファのリミットを設定します。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

System.out.println(buffer); // java.nio.HeapFloatBuffer[pos=0 lim=5 cap=5]
System.out.println(buffer.limit()); // 5

System.out.println(buffer.limit(3)); // java.nio.HeapFloatBuffer[pos=0 lim=3 cap=5]
System.out.println(buffer.limit()); // 3

System.out.println(buffer.clear()); // java.nio.HeapFloatBuffer[pos=0 lim=5 cap=5]
System.out.println(buffer.limit()); // 5

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

System.out.println(buffer.limit(3)); // java.nio.HeapFloatBuffer[pos=0 lim=3 cap=5]

System.out.println(buffer.get()); // 0.1
System.out.println(buffer.get()); // 0.2
System.out.println(buffer.get()); // 0.3

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

// 結果
// ↓
//BufferUnderflowException!

final FloatBuffer mark ()

このバッファの現在位置にマークを設定します。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

System.out.println(buffer.get()); // 0.1
System.out.println(buffer.get()); // 0.2

System.out.println(buffer.position()); // 2
System.out.println(buffer.mark()); // java.nio.HeapFloatBuffer[pos=2 lim=5 cap=5]

System.out.println(buffer.get()); // 0.3
System.out.println(buffer.get()); // 0.4
System.out.println(buffer.get()); // 0.5

System.out.println(buffer.position()); // 5
System.out.println(buffer.reset()); // java.nio.HeapFloatBuffer[pos=2 lim=5 cap=5]

System.out.println(buffer.get()); // 0.3
System.out.println(buffer.get()); // 0.4
System.out.println(buffer.get()); // 0.5

int mismatch (FloatBuffer 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 float[] array = {0.1f, 0.2f, 0.3f, 0.4f};
final var buffer = FloatBuffer.wrap(array);

{
    final float[] a = {0.1f};
    final var that = FloatBuffer.wrap(a);

    System.out.println(buffer.mismatch(that)); // 1
}
{
    final float[] a = {0.1f, 0.2f};
    final var that = FloatBuffer.wrap(a);

    System.out.println(buffer.mismatch(that)); // 2
}
{
    final float[] a = {0.1f, 0.2f, 0.3f};
    final var that = FloatBuffer.wrap(a);

    System.out.println(buffer.mismatch(that)); // 3
}
{
    final float[] a = {0.1f, 0.2f, 0.3f, 0.4f};
    final var that = FloatBuffer.wrap(a);

    System.out.println(buffer.mismatch(that)); // -1
}
{
    final float[] a = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
    final var that = FloatBuffer.wrap(a);

    System.out.println(buffer.mismatch(that)); // 4
}
{
    final float[] a = {0.1f, 0.2f, 0.999f};
    final var that = FloatBuffer.wrap(a); // 2

    System.out.println(buffer.mismatch(that));
}
{
    final float[] a = {-0.9f, -0.8f};
    final var that = FloatBuffer.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 = FloatBuffer.allocate(5);
System.out.println(buffer.order()); // LITTLE_ENDIAN

final FloatBuffer position (int newPosition)

このバッファの位置を設定します。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

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

System.out.println(buffer.get()); // 0.1
System.out.println(buffer.position()); // 1

System.out.println(buffer.get()); // 0.2
System.out.println(buffer.position()); // 2

System.out.println(buffer.get()); // 0.3
System.out.println(buffer.position()); // 3

System.out.println(buffer.get()); // 0.4
System.out.println(buffer.position()); // 4

System.out.println(buffer.get()); // 0.5
System.out.println(buffer.position()); // 5

System.out.println(buffer.position(3)); // java.nio.HeapFloatBuffer[pos=3 lim=5 cap=5]

System.out.println(buffer.get()); // 0.4
System.out.println(buffer.position()); // 4

System.out.println(buffer.get()); // 0.5
System.out.println(buffer.position()); // 5

abstract FloatBuffer put (float f)

相対putメソッドです (オプションの操作)。

final var buffer = FloatBuffer.allocate(5);

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

System.out.println(buffer.put(0.1f)); // java.nio.HeapFloatBuffer[pos=1 lim=5 cap=5]
System.out.println(buffer.put(0.2f)); // java.nio.HeapFloatBuffer[pos=2 lim=5 cap=5]
System.out.println(buffer.put(0.3f)); // java.nio.HeapFloatBuffer[pos=3 lim=5 cap=5]
System.out.println(buffer.put(0.4f)); // java.nio.HeapFloatBuffer[pos=4 lim=5 cap=5]
System.out.println(buffer.put(0.5f)); // java.nio.HeapFloatBuffer[pos=5 lim=5 cap=5]

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

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [0.1, 0.2, 0.3, 0.4, 0.5]
}

final FloatBuffer put (float[] src)

相対一括putメソッドです (オプションの操作)。

final var buffer = FloatBuffer.allocate(6);

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

{
    final float[] src = {0.1f};

    final var ret = buffer.put(src);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=1 lim=6 cap=6]
}
{
    final float[] src = {0.2f, 0.3f};

    final var ret = buffer.put(src);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=3 lim=6 cap=6]
}
{
    final float[] src = {0.4f, 0.5f, 0.6f};

    final var ret = buffer.put(src);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=6 lim=6 cap=6]
}

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

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [0.1, 0.2, 0.3, 0.4, 0.5, 0.6]
}

FloatBuffer put (float[] 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 float[6];
final var buffer = FloatBuffer.wrap(array);

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

final float[] src = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f, 0.6f};

final var ret1 = buffer.put(src, 0, 1);
System.out.println(ret1); // java.nio.HeapFloatBuffer[pos=1 lim=6 cap=6]
System.out.println(Arrays.toString(array)); // [0.1, 0.0, 0.0, 0.0, 0.0, 0.0]

final var ret2 = buffer.put(src, 1, 2);
System.out.println(ret2); // java.nio.HeapFloatBuffer[pos=3 lim=6 cap=6]
System.out.println(Arrays.toString(array)); // [0.1, 0.2, 0.3, 0.0, 0.0, 0.0]

final var ret3 = buffer.put(src, 3, 3);
System.out.println(ret3); // java.nio.HeapFloatBuffer[pos=6 lim=6 cap=6]
System.out.println(Arrays.toString(array)); // [0.1, 0.2, 0.3, 0.4, 0.5, 0.6]

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

abstract FloatBuffer put (int index, float f)

絶対putメソッドです (オプションの操作)。

final var buffer = FloatBuffer.allocate(5);

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

System.out.println(buffer.put(0, 0.1f)); // java.nio.HeapFloatBuffer[pos=0 lim=5 cap=5]
System.out.println(buffer.put(1, 0.2f)); // java.nio.HeapFloatBuffer[pos=0 lim=5 cap=5]
System.out.println(buffer.put(2, 0.3f)); // java.nio.HeapFloatBuffer[pos=0 lim=5 cap=5]
System.out.println(buffer.put(3, 0.4f)); // java.nio.HeapFloatBuffer[pos=0 lim=5 cap=5]
System.out.println(buffer.put(4, 0.5f)); // java.nio.HeapFloatBuffer[pos=0 lim=5 cap=5]

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

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [0.1, 0.2, 0.3, 0.4, 0.5]
}

FloatBuffer put (int index, float[] src)

(optional operation)の絶対一括putメソッド。

final var buffer = FloatBuffer.allocate(6);

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

{
    final float[] src = {0.1f};

    final var ret = buffer.put(0, src);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=0 lim=6 cap=6]
}
{
    final float[] src = {0.2f, 0.3f};

    final var ret = buffer.put(1, src);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=0 lim=6 cap=6]
}
{
    final float[] src = {0.4f, 0.5f, 0.6f};

    final var ret = buffer.put(3, src);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=0 lim=6 cap=6]
}

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

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [0.1, 0.2, 0.3, 0.4, 0.5, 0.6]
}

FloatBuffer put (int index, float[] src, int offset, int length)

(optional operation)の絶対一括putメソッド。

final var array = new float[6];
final var buffer = FloatBuffer.wrap(array);

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

final float[] src = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f, 0.6f};

final var ret1 = buffer.put(0, src, 0, 1);
System.out.println(ret1); // java.nio.HeapFloatBuffer[pos=0 lim=6 cap=6]
System.out.println(Arrays.toString(array)); // [0.1, 0.0, 0.0, 0.0, 0.0, 0.0]

final var ret2 = buffer.put(1, src, 1, 2);
System.out.println(ret2); // java.nio.HeapFloatBuffer[pos=0 lim=6 cap=6]
System.out.println(Arrays.toString(array)); // [0.1, 0.2, 0.3, 0.0, 0.0, 0.0]

final var ret3 = buffer.put(3, src, 3, 3);
System.out.println(ret3); // java.nio.HeapFloatBuffer[pos=0 lim=6 cap=6]
System.out.println(Arrays.toString(array)); // [0.1, 0.2, 0.3, 0.4, 0.5, 0.6]

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

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

(optional operation)の絶対一括putメソッド。

final var array = new float[6];
final var buffer = FloatBuffer.wrap(array);

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

final float[] srcArray = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f, 0.6f};
final var src = FloatBuffer.wrap(srcArray);

final var ret1 = buffer.put(0, src, 0, 1);
System.out.println(ret1); // java.nio.HeapFloatBuffer[pos=0 lim=6 cap=6]
System.out.println(Arrays.toString(array)); // [0.1, 0.0, 0.0, 0.0, 0.0, 0.0]

final var ret2 = buffer.put(1, src, 1, 2);
System.out.println(ret2); // java.nio.HeapFloatBuffer[pos=0 lim=6 cap=6]
System.out.println(Arrays.toString(array)); // [0.1, 0.2, 0.3, 0.0, 0.0, 0.0]

final var ret3 = buffer.put(3, src, 3, 3);
System.out.println(ret3); // java.nio.HeapFloatBuffer[pos=0 lim=6 cap=6]
System.out.println(Arrays.toString(array)); // [0.1, 0.2, 0.3, 0.4, 0.5, 0.6]

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

FloatBuffer put (FloatBuffer src)

相対一括putメソッドです (オプションの操作)。

final var buffer = FloatBuffer.allocate(5);

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

{
    final float[] array = {0.1f, 0.2f};
    final var src = FloatBuffer.wrap(array);

    final var ret = buffer.put(src);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=2 lim=5 cap=5]
}
{
    final float[] array = {0.3f, 0.4f, 0.5f};
    final var src = FloatBuffer.wrap(array);

    final var ret = buffer.put(src);
    System.out.println(ret); // java.nio.HeapFloatBuffer[pos=5 lim=5 cap=5]
}

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

if (buffer.hasArray()) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [0.1, 0.2, 0.3, 0.4, 0.5]
}

final FloatBuffer 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 float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

System.out.println(buffer.get()); // 0.1
System.out.println(buffer.get()); // 0.2

System.out.println(buffer.position()); // 2
System.out.println(buffer.mark()); // java.nio.HeapFloatBuffer[pos=2 lim=5 cap=5]

System.out.println(buffer.get()); // 0.3
System.out.println(buffer.get()); // 0.4
System.out.println(buffer.get()); // 0.5

System.out.println(buffer.position()); // 5
System.out.println(buffer.reset()); // java.nio.HeapFloatBuffer[pos=2 lim=5 cap=5]

System.out.println(buffer.get()); // 0.3
System.out.println(buffer.get()); // 0.4
System.out.println(buffer.get()); // 0.5

final FloatBuffer rewind ()

このバッファをリワインド(巻き戻し)します。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

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

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

System.out.println(buffer.rewind()); // java.nio.HeapFloatBuffer[pos=0 lim=4 cap=5]

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

abstract FloatBuffer slice ()

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

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

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

final var sliced = buffer.slice();

System.out.println(buffer); // java.nio.HeapFloatBuffer[pos=1 lim=4 cap=5]
System.out.println(sliced); // java.nio.HeapFloatBuffer[pos=0 lim=3 cap=3]

System.out.println(buffer.get()); // 0.2
System.out.println(buffer.get()); // 0.3
System.out.println(buffer.get()); // 0.4
System.out.println(buffer.hasRemaining()); // false

System.out.println(sliced.get()); // 0.2
System.out.println(sliced.get()); // 0.3
System.out.println(sliced.get()); // 0.4
System.out.println(sliced.hasRemaining()); // false

abstract FloatBuffer slice (int index, int length)

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

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

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

System.out.println(buffer); // java.nio.HeapFloatBuffer[pos=0 lim=5 cap=5]
System.out.println(sliced); // java.nio.HeapFloatBuffer[pos=0 lim=3 cap=3]

System.out.println(buffer.get()); // 0.1
System.out.println(buffer.get()); // 0.2
System.out.println(buffer.get()); // 0.3
System.out.println(buffer.get()); // 0.4
System.out.println(buffer.get()); // 0.5
System.out.println(buffer.hasRemaining()); // false

System.out.println(sliced.get()); // 0.3
System.out.println(sliced.get()); // 0.4
System.out.println(sliced.get()); // 0.5
System.out.println(sliced.hasRemaining()); // false

String toString ()

このバッファの状態を要約した文字列を返します。

final var buffer = FloatBuffer.allocate(5)
        .limit(4)
        .position(2);

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

final var str1 = buffer.toString();
System.out.println(str1); // java.nio.HeapFloatBuffer[pos=2 lim=4 cap=5]

buffer.clear();

final var str2 = buffer.toString();
System.out.println(str2); // java.nio.HeapFloatBuffer[pos=0 lim=5 cap=5]

static FloatBuffer wrap (float[] array)

float配列をバッファにラップします。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f};
final var buffer = FloatBuffer.wrap(array);

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

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

    System.out.println(buffer.get()); // 0.1
    System.out.println(buffer.get()); // 0.2
    System.out.println(buffer.get()); // 0.3
    System.out.println(buffer.get()); // 0.4
    System.out.println(buffer.get()); // 0.5
}

static FloatBuffer wrap (float[] array, int offset, int length)

float配列をバッファにラップします。

final float[] array = {0.1f, 0.2f, 0.3f, 0.4f, 0.5f, 0.6f, 0.7f};
final var buffer = FloatBuffer.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()); // 0.3
    System.out.println(buffer.get()); // 0.4
    System.out.println(buffer.get()); // 0.5
    System.out.println(buffer.get()); // 0.6
}

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。

API 使用例
- Buffer

Java : FloatBuffer - API使用例

概要

メソッド

static FloatBuffer allocate (int capacity)

final float[] array ()

final int arrayOffset ()

abstract FloatBuffer asReadOnlyBuffer ()

final FloatBuffer clear ()

abstract FloatBuffer compact ()

int compareTo (FloatBuffer that)

abstract FloatBuffer duplicate ()

boolean equals (Object ob)

final FloatBuffer flip ()

abstract float get ()

FloatBuffer get (float[] dst)

FloatBuffer get (float[] dst, int offset, int length)

abstract float get (int index)

FloatBuffer get (int index, float[] dst)

FloatBuffer get (int index, float[] dst, int offset, int length)

final boolean hasArray ()

int hashCode ()

abstract boolean isDirect ()

final FloatBuffer limit (int newLimit)

final FloatBuffer mark ()

int mismatch (FloatBuffer that)

abstract ByteOrder order ()

final FloatBuffer position (int newPosition)

abstract FloatBuffer put (float f)

final FloatBuffer put (float[] src)

FloatBuffer put (float[] src, int offset, int length)

abstract FloatBuffer put (int index, float f)

FloatBuffer put (int index, float[] src)

FloatBuffer put (int index, float[] src, int offset, int length)

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

FloatBuffer put (FloatBuffer src)

final FloatBuffer reset ()

final FloatBuffer rewind ()

abstract FloatBuffer slice ()

abstract FloatBuffer slice (int index, int length)

String toString ()

static FloatBuffer wrap (float[] array)

static FloatBuffer wrap (float[] array, int offset, int length)

Bufferで宣言されたメソッド

capacity, hasRemaining, isReadOnly, limit, position, remaining

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