Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package java.nio; /** A buffer of floats. * <p> * A float buffer can be created in either of the following ways: * </p> * <ul> * <li>{@link #allocate(int) Allocate} a new float array and create a buffer based on it;</li> * <li>{@link #wrap(float[]) Wrap} an existing float array to create a new buffer;</li> * <li>Use {@link java.nio.ByteBuffer#asFloatBuffer() ByteBuffer.asFloatBuffer} to create a float buffer based on a byte buffer.</li> * </ul> * * @since Android 1.0 */ public abstract class FloatBuffer extends Buffer implements Comparable<FloatBuffer> { /** Creates a float buffer based on a newly allocated float array. * * @param capacity the capacity of the new buffer. * @return the created float buffer. * @throws IllegalArgumentException if {@code capacity} is less than zero. * @since Android 1.0 */ public static FloatBuffer allocate(int capacity) { if (capacity < 0) { throw new IllegalArgumentException(); } return BufferFactory.newFloatBuffer(capacity); } /** Creates a new float buffer by wrapping the given float array. * <p> * Calling this method has the same effect as {@code wrap(array, 0, array.length)}. * </p> * * @param array the float array which the new buffer will be based on. * @return the created float buffer. * @since Android 1.0 */ public static FloatBuffer wrap(float[] array) { return wrap(array, 0, array.length); } /** Creates a new float buffer by wrapping the given float array. * <p> * The new buffer's position will be {@code start}, limit will be {@code start + len}, capacity will be the length of the array. * </p> * * @param array the float array which the new buffer will be based on. * @param start the start index, must not be negative and not greater than {@code array.length}. * @param len the length, must not be negative and not greater than {@code array.length - start}. * @return the created float buffer. * @exception IndexOutOfBoundsException if either {@code start} or {@code len} is invalid. * @exception NullPointerException if {@code array} is null. * @since Android 1.0 */ public static FloatBuffer wrap(float[] array, int start, int len) { if (array == null) { throw new NullPointerException(); } if (start < 0 || len < 0 || (long) start + (long) len > array.length) { throw new IndexOutOfBoundsException(); } FloatBuffer buf = BufferFactory.newFloatBuffer(array); buf.position = start; buf.limit = start + len; return buf; } /** Constructs a {@code FloatBuffer} with given capacity. * * @param capacity The capacity of the buffer */ FloatBuffer(int capacity) { super(capacity); } /** Returns the float array which this buffer is based on, if there is one. * * @return the float array which this buffer is based on. * @exception ReadOnlyBufferException if this buffer is based on an array, but it is read-only. * @exception UnsupportedOperationException if this buffer is not based on an array. * @since Android 1.0 */ public final float[] array() { return protectedArray(); } /** Returns the offset of the float array which this buffer is based on, if there is one. * <p> * The offset is the index of the array and corresponds to the zero position of the buffer. * </p> * * @return the offset of the float array which this buffer is based on. * @exception ReadOnlyBufferException if this buffer is based on an array, but it is read-only. * @exception UnsupportedOperationException if this buffer is not based on an array. * @since Android 1.0 */ public final int arrayOffset() { return protectedArrayOffset(); } /** Returns a read-only buffer that shares its content with this buffer. * <p> * The returned buffer is guaranteed to be a new instance, even if this buffer is read-only itself. The new buffer's position, * limit, capacity and mark are the same as this buffer. * </p> * <p> * The new buffer shares its content with this buffer, which means this buffer's change of content will be visible to the new * buffer. The two buffer's position, limit and mark are independent. * </p> * * @return a read-only version of this buffer. * @since Android 1.0 */ public abstract FloatBuffer asReadOnlyBuffer(); /** Compacts this float buffer. * <p> * The remaining floats will be moved to the head of the buffer, starting from position zero. Then the position is set to * {@code remaining()}; the limit is set to capacity; the mark is cleared. * </p> * * @return this buffer. * @exception ReadOnlyBufferException if no changes may be made to the contents of this buffer. * @since Android 1.0 */ public abstract FloatBuffer compact(); /** Compare the remaining floats of this buffer to another float buffer's remaining floats. * * @param otherBuffer another float buffer. * @return a negative value if this is less than {@code otherBuffer}; 0 if this equals to {@code otherBuffer}; a positive value * if this is greater than {@code otherBuffer}. * @exception ClassCastException if {@code otherBuffer} is not a float buffer. * @since Android 1.0 */ public int compareTo(FloatBuffer otherBuffer) { int compareRemaining = (remaining() < otherBuffer.remaining()) ? remaining() : otherBuffer.remaining(); int thisPos = position; int otherPos = otherBuffer.position; // BEGIN android-changed float thisFloat, otherFloat; while (compareRemaining > 0) { thisFloat = get(thisPos); otherFloat = otherBuffer.get(otherPos); // checks for float and NaN inequality if ((thisFloat != otherFloat) && ((thisFloat == thisFloat) || (otherFloat == otherFloat))) { return thisFloat < otherFloat ? -1 : 1; } thisPos++; otherPos++; compareRemaining--; } // END android-changed return remaining() - otherBuffer.remaining(); } /** Returns a duplicated buffer that shares its content with this buffer. * <p> * The duplicated buffer's position, limit, capacity and mark are the same as this buffer. The duplicated buffer's read-only * property and byte order are same as this buffer too. * </p> * <p> * The new buffer shares its content with this buffer, which means either buffer's change of content will be visible to the * other. The two buffer's position, limit and mark are independent. * </p> * * @return a duplicated buffer that shares its content with this buffer. * @since Android 1.0 */ public abstract FloatBuffer duplicate(); /** Checks whether this float buffer is equal to another object. * <p> * If {@code other} is not a float buffer then {@code false} is returned. Two float buffers are equal if and only if their * remaining floats are exactly the same. Position, limit, capacity and mark are not considered. * </p> * * @param other the object to compare with this float buffer. * @return {@code true} if this float buffer is equal to {@code other}, {@code false} otherwise. * @since Android 1.0 */ public boolean equals(Object other) { if (!(other instanceof FloatBuffer)) { return false; } FloatBuffer otherBuffer = (FloatBuffer) other; if (remaining() != otherBuffer.remaining()) { return false; } int myPosition = position; int otherPosition = otherBuffer.position; boolean equalSoFar = true; while (equalSoFar && (myPosition < limit)) { equalSoFar = get(myPosition++) == otherBuffer.get(otherPosition++); } return equalSoFar; } /** Returns the float at the current position and increases the position by 1. * * @return the float at the current position. * @exception BufferUnderflowException if the position is equal or greater than limit. * @since Android 1.0 */ public abstract float get(); /** Reads floats from the current position into the specified float array and increases the position by the number of floats * read. * <p> * Calling this method has the same effect as {@code get(dest, 0, dest.length)}. * </p> * * @param dest the destination float array. * @return this buffer. * @exception BufferUnderflowException if {@code dest.length} is greater than {@code remaining()}. * @since Android 1.0 */ public FloatBuffer get(float[] dest) { return get(dest, 0, dest.length); } /** Reads floats from the current position into the specified float array, starting from the specified offset, and increases the * position by the number of floats read. * * @param dest the target float array. * @param off the offset of the float array, must not be negative and no greater than {@code dest.length}. * @param len the number of floats to read, must be no less than zero and no greater than {@code dest.length - off}. * @return this buffer. * @exception IndexOutOfBoundsException if either {@code off} or {@code len} is invalid. * @exception BufferUnderflowException if {@code len} is greater than {@code remaining()}. * @since Android 1.0 */ public FloatBuffer get(float[] dest, int off, int len) { int length = dest.length; if (off < 0 || len < 0 || (long) off + (long) len > length) { throw new IndexOutOfBoundsException(); } if (len > remaining()) { throw new BufferUnderflowException(); } for (int i = off; i < off + len; i++) { dest[i] = get(); } return this; } /** Returns a float at the specified index; the position is not changed. * * @param index the index, must not be negative and less than limit. * @return a float at the specified index. * @exception IndexOutOfBoundsException if index is invalid. * @since Android 1.0 */ public abstract float get(int index); /** Indicates whether this buffer is based on a float array and is read/write. * * @return {@code true} if this buffer is based on a float array and provides read/write access, {@code false} otherwise. * @since Android 1.0 */ public final boolean hasArray() { return protectedHasArray(); } // /** // * Calculates this buffer's hash code from the remaining chars. The // * position, limit, capacity and mark don't affect the hash code. // * // * @return the hash code calculated from the remaining floats. // * @since Android 1.0 // */ // public int hashCode() { // int myPosition = position; // int hash = 0; // while (myPosition < limit) { // hash = hash + Float.floatToIntBits(get(myPosition++)); // } // return hash; // } /** Indicates whether this buffer is direct. A direct buffer will try its best to take advantage of native memory APIs and it * may not stay in the Java heap, so it is not affected by garbage collection. * <p> * A float buffer is direct if it is based on a byte buffer and the byte buffer is direct. * </p> * * @return {@code true} if this buffer is direct, {@code false} otherwise. * @since Android 1.0 */ public abstract boolean isDirect(); /** Returns the byte order used by this buffer when converting floats from/to bytes. * <p> * If this buffer is not based on a byte buffer, then always return the platform's native byte order. * </p> * * @return the byte order used by this buffer when converting floats from/to bytes. * @since Android 1.0 */ public abstract ByteOrder order(); /** Child class implements this method to realize {@code array()}. * * @return see {@code array()} */ abstract float[] protectedArray(); /** Child class implements this method to realize {@code arrayOffset()}. * * @return see {@code arrayOffset()} */ abstract int protectedArrayOffset(); /** Child class implements this method to realize {@code hasArray()}. * * @return see {@code hasArray()} */ abstract boolean protectedHasArray(); /** Writes the given float to the current position and increases the position by 1. * * @param f the float to write. * @return this buffer. * @exception BufferOverflowException if position is equal or greater than limit. * @exception ReadOnlyBufferException if no changes may be made to the contents of this buffer. * @since Android 1.0 */ public abstract FloatBuffer put(float f); /** Writes floats from the given float array to the current position and increases the position by the number of floats written. * <p> * Calling this method has the same effect as {@code put(src, 0, src.length)}. * </p> * * @param src the source float array. * @return this buffer. * @exception BufferOverflowException if {@code remaining()} is less than {@code src.length}. * @exception ReadOnlyBufferException if no changes may be made to the contents of this buffer. * @since Android 1.0 */ public final FloatBuffer put(float[] src) { return put(src, 0, src.length); } /** Writes floats from the given float array, starting from the specified offset, to the current position and increases the * position by the number of floats written. * * @param src the source float array. * @param off the offset of float array, must not be negative and not greater than {@code src.length}. * @param len the number of floats to write, must be no less than zero and no greater than {@code src.length - off}. * @return this buffer. * @exception BufferOverflowException if {@code remaining()} is less than {@code len}. * @exception IndexOutOfBoundsException if either {@code off} or {@code len} is invalid. * @exception ReadOnlyBufferException if no changes may be made to the contents of this buffer. * @since Android 1.0 */ public FloatBuffer put(float[] src, int off, int len) { int length = src.length; if (off < 0 || len < 0 || (long) off + (long) len > length) { throw new IndexOutOfBoundsException(); } if (len > remaining()) { throw new BufferOverflowException(); } for (int i = off; i < off + len; i++) { put(src[i]); } return this; } /** Writes all the remaining floats of the {@code src} float buffer to this buffer's current position, and increases both * buffers' position by the number of floats copied. * * @param src the source float buffer. * @return this buffer. * @exception BufferOverflowException if {@code src.remaining()} is greater than this buffer's {@code remaining()}. * @exception IllegalArgumentException if {@code src} is this buffer. * @exception ReadOnlyBufferException if no changes may be made to the contents of this buffer. * @since Android 1.0 */ public FloatBuffer put(FloatBuffer src) { if (src == this) { throw new IllegalArgumentException(); } if (src.remaining() > remaining()) { throw new BufferOverflowException(); } float[] contents = new float[src.remaining()]; src.get(contents); put(contents); return this; } /** Writes a float to the specified index of this buffer; the position is not changed. * * @param index the index, must not be negative and less than the limit. * @param f the float to write. * @return this buffer. * @exception IndexOutOfBoundsException if index is invalid. * @exception ReadOnlyBufferException if no changes may be made to the contents of this buffer. * @since Android 1.0 */ public abstract FloatBuffer put(int index, float f); /** Returns a sliced buffer that shares its content with this buffer. * <p> * The sliced buffer's capacity will be this buffer's {@code remaining()}, and its zero position will correspond to this * buffer's current position. The new buffer's position will be 0, limit will be its capacity, and its mark is cleared. The new * buffer's read-only property and byte order are same as this buffer's. * </p> * <p> * The new buffer shares its content with this buffer, which means either buffer's change of content will be visible to the * other. The two buffer's position, limit and mark are independent. * </p> * * @return a sliced buffer that shares its content with this buffer. * @since Android 1.0 */ public abstract FloatBuffer slice(); /** Returns a string representing the state of this float buffer. * * @return a string representing the state of this float buffer. * @since Android 1.0 */ public String toString() { StringBuffer buf = new StringBuffer(); buf.append(getClass().getName()); buf.append(", status: capacity="); //$NON-NLS-1$ buf.append(capacity()); buf.append(" position="); //$NON-NLS-1$ buf.append(position()); buf.append(" limit="); //$NON-NLS-1$ buf.append(limit()); return buf.toString(); } }