Java tutorial
/******************************************************************************* * Copyright 2011 See AUTHORS file. * * Licensed 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 com.badlogic.gdx.utils; import com.badlogic.gdx.math.MathUtils; import java.util.BitSet; /** A resizable, ordered or unordered boolean array. Avoids the boxing that occurs with ArrayList<Boolean>. It is less memory * efficient than {@link BitSet}, except for very small sizes. It more CPU efficient than {@link BitSet}, except for very large * sizes or if BitSet functionality such as and, or, xor, etc are needed. If unordered, this class avoids a memory copy when * removing elements (the last element is moved to the removed element's position). * @author Nathan Sweet */ public class BooleanArray { public boolean[] items; public int size; public boolean ordered; /** Creates an ordered array with a capacity of 16. */ public BooleanArray() { this(true, 16); } /** Creates an ordered array with the specified capacity. */ public BooleanArray(int capacity) { this(true, capacity); } /** @param ordered If false, methods that remove elements may change the order of other elements in the array, which avoids a * memory copy. * @param capacity Any elements added beyond this will cause the backing array to be grown. */ public BooleanArray(boolean ordered, int capacity) { this.ordered = ordered; items = new boolean[capacity]; } /** Creates a new array containing the elements in the specific array. The new array will be ordered if the specific array is * ordered. The capacity is set to the number of elements, so any subsequent elements added will cause the backing array to be * grown. */ public BooleanArray(BooleanArray array) { this.ordered = array.ordered; size = array.size; items = new boolean[size]; System.arraycopy(array.items, 0, items, 0, size); } /** Creates a new ordered array containing the elements in the specified array. The capacity is set to the number of elements, * so any subsequent elements added will cause the backing array to be grown. */ public BooleanArray(boolean[] array) { this(true, array, 0, array.length); } /** Creates a new array containing the elements in the specified array. The capacity is set to the number of elements, so any * subsequent elements added will cause the backing array to be grown. * @param ordered If false, methods that remove elements may change the order of other elements in the array, which avoids a * memory copy. */ public BooleanArray(boolean ordered, boolean[] array, int startIndex, int count) { this(ordered, count); size = count; System.arraycopy(array, startIndex, items, 0, count); } public void add(boolean value) { boolean[] items = this.items; if (size == items.length) items = resize(Math.max(8, (int) (size * 1.75f))); items[size++] = value; } public void addAll(BooleanArray array) { addAll(array, 0, array.size); } public void addAll(BooleanArray array, int offset, int length) { if (offset + length > array.size) throw new IllegalArgumentException( "offset + length must be <= size: " + offset + " + " + length + " <= " + array.size); addAll(array.items, offset, length); } public void addAll(boolean... array) { addAll(array, 0, array.length); } public void addAll(boolean[] array, int offset, int length) { boolean[] items = this.items; int sizeNeeded = size + length; if (sizeNeeded > items.length) items = resize(Math.max(8, (int) (sizeNeeded * 1.75f))); System.arraycopy(array, offset, items, size, length); size += length; } public boolean get(int index) { if (index >= size) throw new IndexOutOfBoundsException("index can't be >= size: " + index + " >= " + size); return items[index]; } public void set(int index, boolean value) { if (index >= size) throw new IndexOutOfBoundsException("index can't be >= size: " + index + " >= " + size); items[index] = value; } public void insert(int index, boolean value) { if (index > size) throw new IndexOutOfBoundsException("index can't be > size: " + index + " > " + size); boolean[] items = this.items; if (size == items.length) items = resize(Math.max(8, (int) (size * 1.75f))); if (ordered) System.arraycopy(items, index, items, index + 1, size - index); else items[size] = items[index]; size++; items[index] = value; } public void swap(int first, int second) { if (first >= size) throw new IndexOutOfBoundsException("first can't be >= size: " + first + " >= " + size); if (second >= size) throw new IndexOutOfBoundsException("second can't be >= size: " + second + " >= " + size); boolean[] items = this.items; boolean firstValue = items[first]; items[first] = items[second]; items[second] = firstValue; } /** Removes and returns the item at the specified index. */ public boolean removeIndex(int index) { if (index >= size) throw new IndexOutOfBoundsException("index can't be >= size: " + index + " >= " + size); boolean[] items = this.items; boolean value = items[index]; size--; if (ordered) System.arraycopy(items, index + 1, items, index, size - index); else items[index] = items[size]; return value; } /** Removes the items between the specified indices, inclusive. */ public void removeRange(int start, int end) { if (end >= size) throw new IndexOutOfBoundsException("end can't be >= size: " + end + " >= " + size); if (start > end) throw new IndexOutOfBoundsException("start can't be > end: " + start + " > " + end); boolean[] items = this.items; int count = end - start + 1; if (ordered) System.arraycopy(items, start + count, items, start, size - (start + count)); else { int lastIndex = this.size - 1; for (int i = 0; i < count; i++) items[start + i] = items[lastIndex - i]; } size -= count; } /** Removes from this array all of elements contained in the specified array. * @return true if this array was modified. */ public boolean removeAll(BooleanArray array) { int size = this.size; int startSize = size; boolean[] items = this.items; for (int i = 0, n = array.size; i < n; i++) { boolean item = array.get(i); for (int ii = 0; ii < size; ii++) { if (item == items[ii]) { removeIndex(ii); size--; break; } } } return size != startSize; } /** Removes and returns the last item. */ public boolean pop() { return items[--size]; } /** Returns the last item. */ public boolean peek() { return items[size - 1]; } /** Returns the first item. */ public boolean first() { if (size == 0) throw new IllegalStateException("Array is empty."); return items[0]; } public void clear() { size = 0; } /** Reduces the size of the backing array to the size of the actual items. This is useful to release memory when many items have * been removed, or if it is known that more items will not be added. * @return {@link #items} */ public boolean[] shrink() { if (items.length != size) resize(size); return items; } /** Increases the size of the backing array to accommodate the specified number of additional items. Useful before adding many * items to avoid multiple backing array resizes. * @return {@link #items} */ public boolean[] ensureCapacity(int additionalCapacity) { int sizeNeeded = size + additionalCapacity; if (sizeNeeded > items.length) resize(Math.max(8, sizeNeeded)); return items; } protected boolean[] resize(int newSize) { boolean[] newItems = new boolean[newSize]; boolean[] items = this.items; System.arraycopy(items, 0, newItems, 0, Math.min(size, newItems.length)); this.items = newItems; return newItems; } public void reverse() { boolean[] items = this.items; for (int i = 0, lastIndex = size - 1, n = size / 2; i < n; i++) { int ii = lastIndex - i; boolean temp = items[i]; items[i] = items[ii]; items[ii] = temp; } } public void shuffle() { boolean[] items = this.items; for (int i = size - 1; i >= 0; i--) { int ii = MathUtils.random(i); boolean temp = items[i]; items[i] = items[ii]; items[ii] = temp; } } /** Reduces the size of the array to the specified size. If the array is already smaller than the specified size, no action is * taken. */ public void truncate(int newSize) { if (size > newSize) size = newSize; } /** Returns a random item from the array, or false if the array is empty. */ public boolean random() { if (size == 0) return false; return items[MathUtils.random(0, size - 1)]; } public boolean[] toArray() { boolean[] array = new boolean[size]; System.arraycopy(items, 0, array, 0, size); return array; } public boolean equals(Object object) { if (object == this) return true; if (!(object instanceof BooleanArray)) return false; BooleanArray array = (BooleanArray) object; int n = size; if (n != array.size) return false; for (int i = 0; i < n; i++) if (items[i] != array.items[i]) return false; return true; } public String toString() { if (size == 0) return "[]"; boolean[] items = this.items; StringBuilder buffer = new StringBuilder(32); buffer.append('['); buffer.append(items[0]); for (int i = 1; i < size; i++) { buffer.append(", "); buffer.append(items[i]); } buffer.append(']'); return buffer.toString(); } public String toString(String separator) { if (size == 0) return ""; boolean[] items = this.items; StringBuilder buffer = new StringBuilder(32); buffer.append(items[0]); for (int i = 1; i < size; i++) { buffer.append(separator); buffer.append(items[i]); } return buffer.toString(); } /** @see #BooleanArray(boolean[]) */ static public BooleanArray with(boolean... array) { return new BooleanArray(array); } }