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 java.util.Comparator; import java.util.Iterator; import java.util.NoSuchElementException; import com.badlogic.gdx.math.MathUtils; import com.badlogic.gdx.utils.reflect.ArrayReflection; /** A resizable, ordered or unordered array of objects. 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 Array<T> implements Iterable<T> { /** Provides direct access to the underlying array. If the Array's generic type is not Object, this field may only be accessed * if the {@link Array#Array(boolean, int, Class)} constructor was used. */ public T[] items; public int size; public boolean ordered; private ArrayIterable iterable; private Predicate.PredicateIterable<T> predicateIterable; /** Creates an ordered array with a capacity of 16. */ public Array() { this(true, 16); } /** Creates an ordered array with the specified capacity. */ public Array(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 Array(boolean ordered, int capacity) { this.ordered = ordered; items = (T[]) new Object[capacity]; } /** Creates a new array with {@link #items} of the specified type. * @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 Array(boolean ordered, int capacity, Class arrayType) { this.ordered = ordered; items = (T[]) ArrayReflection.newInstance(arrayType, capacity); } /** Creates an ordered array with {@link #items} of the specified type and a capacity of 16. */ public Array(Class arrayType) { this(true, 16, arrayType); } /** Creates a new array containing the elements in the specified array. The new array will have the same type of backing array * and will be ordered if the specified 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 Array(Array<? extends T> array) { this(array.ordered, array.size, array.items.getClass().getComponentType()); size = array.size; System.arraycopy(array.items, 0, items, 0, size); } /** Creates a new ordered array containing the elements in the specified array. The new array will have the same type of backing * array. The capacity is set to the number of elements, so any subsequent elements added will cause the backing array to be * grown. */ public Array(T[] array) { this(true, array, 0, array.length); } /** Creates a new array containing the elements in the specified array. The new array will have the same type of backing 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 Array(boolean ordered, T[] array, int start, int count) { this(ordered, count, (Class) array.getClass().getComponentType()); size = count; System.arraycopy(array, 0, items, 0, size); } public void add(T value) { T[] items = this.items; if (size == items.length) items = resize(Math.max(8, (int) (size * 1.75f))); items[size++] = value; } public void addAll(Array<? extends T> array) { addAll(array, 0, array.size); } public void addAll(Array<? extends T> array, int offset, int length) { if (offset + length > array.size) throw new IllegalArgumentException( "offset + length must be <= size: " + offset + " + " + length + " <= " + array.size); addAll((T[]) array.items, offset, length); } public void addAll(T... array) { addAll(array, 0, array.length); } public void addAll(T[] array, int offset, int length) { T[] 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 T get(int index) { if (index >= size) throw new IndexOutOfBoundsException("index can't be >= size: " + index + " >= " + size); return items[index]; } public void set(int index, T value) { if (index >= size) throw new IndexOutOfBoundsException("index can't be >= size: " + index + " >= " + size); items[index] = value; } public void insert(int index, T value) { if (index > size) throw new IndexOutOfBoundsException("index can't be > size: " + index + " > " + size); T[] 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); T[] items = this.items; T firstValue = items[first]; items[first] = items[second]; items[second] = firstValue; } /** Returns if this array contains value. * @param identity If true, == comparison will be used. If false, .equals() comparison will be used. * @return true if array contains value, false if it doesn't */ public boolean contains(T value, boolean identity) { T[] items = this.items; int i = size - 1; if (identity || value == null) { while (i >= 0) if (items[i--] == value) return true; } else { while (i >= 0) if (value.equals(items[i--])) return true; } return false; } /** Returns an index of first occurrence of value in array or -1 if no such value exists * @param identity If true, == comparison will be used. If false, .equals() comparison will be used. * @return An index of first occurrence of value in array or -1 if no such value exists */ public int indexOf(T value, boolean identity) { T[] items = this.items; if (identity || value == null) { for (int i = 0, n = size; i < n; i++) if (items[i] == value) return i; } else { for (int i = 0, n = size; i < n; i++) if (value.equals(items[i])) return i; } return -1; } /** Returns an index of last occurrence of value in array or -1 if no such value exists. Search is started from the end of an * array. * @param identity If true, == comparison will be used. If false, .equals() comparison will be used. * @return An index of last occurrence of value in array or -1 if no such value exists */ public int lastIndexOf(T value, boolean identity) { T[] items = this.items; if (identity || value == null) { for (int i = size - 1; i >= 0; i--) if (items[i] == value) return i; } else { for (int i = size - 1; i >= 0; i--) if (value.equals(items[i])) return i; } return -1; } /** Removes the first instance of the specified value in the array. * @param identity If true, == comparison will be used. If false, .equals() comparison will be used. * @return true if value was found and removed, false otherwise */ public boolean removeValue(T value, boolean identity) { T[] items = this.items; if (identity || value == null) { for (int i = 0, n = size; i < n; i++) { if (items[i] == value) { removeIndex(i); return true; } } } else { for (int i = 0, n = size; i < n; i++) { if (value.equals(items[i])) { removeIndex(i); return true; } } } return false; } /** Removes and returns the item at the specified index. */ public T removeIndex(int index) { if (index >= size) throw new IndexOutOfBoundsException("index can't be >= size: " + index + " >= " + size); T[] items = this.items; T value = (T) items[index]; size--; if (ordered) System.arraycopy(items, index + 1, items, index, size - index); else items[index] = items[size]; items[size] = null; 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); T[] 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. * @param identity True to use ==, false to use .equals(). * @return true if this array was modified. */ public boolean removeAll(Array<? extends T> array, boolean identity) { int size = this.size; int startSize = size; T[] items = this.items; if (identity) { for (int i = 0, n = array.size; i < n; i++) { T item = array.get(i); for (int ii = 0; ii < size; ii++) { if (item == items[ii]) { removeIndex(ii); size--; break; } } } } else { for (int i = 0, n = array.size; i < n; i++) { T item = array.get(i); for (int ii = 0; ii < size; ii++) { if (item.equals(items[ii])) { removeIndex(ii); size--; break; } } } } return size != startSize; } /** Removes and returns the last item. */ public T pop() { if (size == 0) throw new IllegalStateException("Array is empty."); --size; T item = items[size]; items[size] = null; return item; } /** Returns the last item. */ public T peek() { if (size == 0) throw new IllegalStateException("Array is empty."); return items[size - 1]; } /** Returns the first item. */ public T first() { if (size == 0) throw new IllegalStateException("Array is empty."); return items[0]; } public void clear() { T[] items = this.items; for (int i = 0, n = size; i < n; i++) items[i] = null; 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 T[] 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 T[] ensureCapacity(int additionalCapacity) { int sizeNeeded = size + additionalCapacity; if (sizeNeeded > items.length) resize(Math.max(8, sizeNeeded)); return items; } /** Creates a new backing array with the specified size containing the current items. */ protected T[] resize(int newSize) { T[] items = this.items; T[] newItems = (T[]) ArrayReflection.newInstance(items.getClass().getComponentType(), newSize); System.arraycopy(items, 0, newItems, 0, Math.min(size, newItems.length)); this.items = newItems; return newItems; } /** Sorts this array. The array elements must implement {@link Comparable}. This method is not thread safe (uses * {@link Sort#instance()}). */ public void sort() { Sort.instance().sort(items, 0, size); } /** Sorts the array. This method is not thread safe (uses {@link Sort#instance()}). */ public void sort(Comparator<? super T> comparator) { Sort.instance().sort(items, comparator, 0, size); } /** Selects the nth-lowest element from the Array according to Comparator ranking. This might partially sort the Array. The * array must have a size greater than 0, or a {@link com.badlogic.gdx.utils.GdxRuntimeException} will be thrown. * @see Select * @param comparator used for comparison * @param kthLowest rank of desired object according to comparison, n is based on ordinal numbers, not array indices. for min * value use 1, for max value use size of array, using 0 results in runtime exception. * @return the value of the Nth lowest ranked object. */ public T selectRanked(Comparator<T> comparator, int kthLowest) { if (kthLowest < 1) { throw new GdxRuntimeException("nth_lowest must be greater than 0, 1 = first, 2 = second..."); } return Select.instance().select(items, comparator, kthLowest, size); } /** @see Array#selectRanked(java.util.Comparator, int) * @param comparator used for comparison * @param kthLowest rank of desired object according to comparison, n is based on ordinal numbers, not array indices. for min * value use 1, for max value use size of array, using 0 results in runtime exception. * @return the index of the Nth lowest ranked object. */ public int selectRankedIndex(Comparator<T> comparator, int kthLowest) { if (kthLowest < 1) { throw new GdxRuntimeException("nth_lowest must be greater than 0, 1 = first, 2 = second..."); } return Select.instance().selectIndex(items, comparator, kthLowest, size); } public void reverse() { T[] items = this.items; for (int i = 0, lastIndex = size - 1, n = size / 2; i < n; i++) { int ii = lastIndex - i; T temp = items[i]; items[i] = items[ii]; items[ii] = temp; } } public void shuffle() { T[] items = this.items; for (int i = size - 1; i >= 0; i--) { int ii = MathUtils.random(i); T temp = items[i]; items[i] = items[ii]; items[ii] = temp; } } /** Returns an iterator for the items in the array. Remove is supported. Note that the same iterator instance is returned each * time this method is called. Use the {@link ArrayIterator} constructor for nested or multithreaded iteration. */ public Iterator<T> iterator() { if (iterable == null) iterable = new ArrayIterable(this); return iterable.iterator(); } /** Returns an iterable for the selected items in the array. Remove is supported, but not between hasNext() and next(). Note * that the same iterable instance is returned each time this method is called. Use the {@link Predicate.PredicateIterable} * constructor for nested or multithreaded iteration. */ public Iterable<T> select(Predicate<T> predicate) { if (predicateIterable == null) predicateIterable = new Predicate.PredicateIterable<T>(this, predicate); else predicateIterable.set(this, predicate); return predicateIterable; } /** 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) return; for (int i = newSize; i < size; i++) items[i] = null; size = newSize; } /** Returns a random item from the array, or null if the array is empty. */ public T random() { if (size == 0) return null; return items[MathUtils.random(0, size - 1)]; } /** Returns the items as an array. Note the array is typed, so the {@link #Array(Class)} constructor must have been used. * Otherwise use {@link #toArray(Class)} to specify the array type. */ public T[] toArray() { return (T[]) toArray(items.getClass().getComponentType()); } public <V> V[] toArray(Class type) { V[] result = (V[]) ArrayReflection.newInstance(type, size); System.arraycopy(items, 0, result, 0, size); return result; } public boolean equals(Object object) { if (object == this) return true; if (!(object instanceof Array)) return false; Array array = (Array) object; int n = size; if (n != array.size) return false; Object[] items1 = this.items; Object[] items2 = array.items; for (int i = 0; i < n; i++) { Object o1 = items1[i]; Object o2 = items2[i]; if (!(o1 == null ? o2 == null : o1.equals(o2))) return false; } return true; } public String toString() { if (size == 0) return "[]"; T[] 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 ""; T[] 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 #Array(Class) */ static public <T> Array<T> of(Class<T> arrayType) { return new Array<T>(arrayType); } /** @see #Array(boolean, int, Class) */ static public <T> Array<T> of(boolean ordered, int capacity, Class<T> arrayType) { return new Array<T>(ordered, capacity, arrayType); } /** @see #Array(Object[]) */ static public <T> Array<T> with(T... array) { return new Array(array); } static public class ArrayIterator<T> implements Iterator<T>, Iterable<T> { private final Array<T> array; private final boolean allowRemove; int index; boolean valid = true; // ArrayIterable<T> iterable; public ArrayIterator(Array<T> array) { this(array, true); } public ArrayIterator(Array<T> array, boolean allowRemove) { this.array = array; this.allowRemove = allowRemove; } public boolean hasNext() { if (!valid) { // System.out.println(iterable.lastAcquire); throw new GdxRuntimeException("#iterator() cannot be used nested."); } return index < array.size; } public T next() { if (index >= array.size) throw new NoSuchElementException(String.valueOf(index)); if (!valid) { // System.out.println(iterable.lastAcquire); throw new GdxRuntimeException("#iterator() cannot be used nested."); } return array.items[index++]; } public void remove() { if (!allowRemove) throw new GdxRuntimeException("Remove not allowed."); index--; array.removeIndex(index); } public void reset() { index = 0; } public Iterator<T> iterator() { return this; } } static public class ArrayIterable<T> implements Iterable<T> { private final Array<T> array; private final boolean allowRemove; private ArrayIterator iterator1, iterator2; // java.io.StringWriter lastAcquire = new java.io.StringWriter(); public ArrayIterable(Array<T> array) { this(array, true); } public ArrayIterable(Array<T> array, boolean allowRemove) { this.array = array; this.allowRemove = allowRemove; } public Iterator<T> iterator() { // lastAcquire.getBuffer().setLength(0); // new Throwable().printStackTrace(new java.io.PrintWriter(lastAcquire)); if (iterator1 == null) { iterator1 = new ArrayIterator(array, allowRemove); iterator2 = new ArrayIterator(array, allowRemove); // iterator1.iterable = this; // iterator2.iterable = this; } if (!iterator1.valid) { iterator1.index = 0; iterator1.valid = true; iterator2.valid = false; return iterator1; } iterator2.index = 0; iterator2.valid = true; iterator1.valid = false; return iterator2; } } }