arraylist.java

最强手机阅读器Anyview3.0版的界面代码

/*
 * Created on 03-Jan-2004 at 17:08:51.
 *
 * Copyright (c) 2004-2005 Robert Virkus / Enough Software
 *
 * This file is part of J2ME Polish.
 *
 * J2ME Polish is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * J2ME Polish is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with J2ME Polish; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 * 
 * Commercial licenses are also available, please
 * refer to the accompanying LICENSE.txt or visit
 * http://www.j2mepolish.org for details.
 */
package com.ismyway.util;

/**
 * <p>Provides an flexible list for storing objects.</p>
 * <p>
 * This ArrayList is mostly compatible with the java.util.ArrayList of the J2SE.
 * It lacks, however, some not often used methods. Also some methods like add or remove 
 * do not return a boolean value, since true is always returned (or an exception is thrown) anyhow.
 * This way we can save some precious space!
 * </p>
 * <p>
 * Workarounds for some of the missing methods:
 * <ul>
 * 	<li><b>isEmpty()</b> Use "list.size() == 0" instead.</li> 
 *		<li><b>ensureCapacity(int)</b> Define the expected capacity in the constructor.</li>
 *		<li><b>indexOf(Object)/lastIndexOf(Object)</b> You have to do them manually. 
 *				Use "list.toArray()" to get the stored objects, cycle through them and test for equality.</li>
 * 	<li><b>addAll(Collection)</b> Add all elements of the collection singlely.</li> 
 * </ul>
 * </p>
 * @author Robert Virkus, [e-mail]
 * <pre>
 * history
 *        03-Jan-2004 - rob creation
 * </pre>
 */
public class ArrayList {
	private Object[] storedObjects;
	private int growthFactor;
	private int size;

	/**
	 * Creates an ArrayList with the initial capacity of 10 and a growth factor of 75%
	 */
	public ArrayList() {
		this(10, 75);
	}

	/**
	 * creates an ArrayList with the given initial capacity and a growth factor of 75%
	 * 
	 * @param initialCapacity the capacity of this array list.
	 */
	public ArrayList(int initialCapacity) {
		this(initialCapacity, 75);
	}

	/**
	 * Creates a new ArrayList
	 * 
	 * @param initialCapacity the capacity of this array list.
	 * @param growthFactor the factor in % for increasing the capacity 
	 * 								  when there's not enough room in this list anymore 
	 */
	public ArrayList(int initialCapacity, int growthFactor) {
		this.storedObjects = new Object[initialCapacity];
		this.growthFactor = growthFactor;
	}

	/**
	 * Retrieves the current size of this array list.
	 *  
	 * @return the number of stored elements in this list.
	 */
	public int size() {
		return this.size;
	}

	/**
	 * Determines whether the given element is stored in this list.
	 * 
	 * @param element the element which might be stored in this list
	 * @return true when the given element is stored in this list
	 * @throws IllegalArgumentException when the given element is null
	 * @see #remove(Object)
	 */
	public boolean contains(Object element) {
		if (element == null) {
			throw new IllegalArgumentException("ArrayList cannot contain a null element.");
		}
		for (int i = 0; i < this.size; i++) {
			Object object = this.storedObjects[i];
			if (object.equals(element)) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Retrieves the index of the given object.
	 * 
	 * @param element the object which is part of this list.
	 * @return the index of the object or -1 when the object is not part of this list.
	 * @throws IllegalArgumentException when the given element is null
	 */
	public int indexOf(Object element) {
		if (element == null) {
			throw new IllegalArgumentException("ArrayList cannot contain a null element.");
		}
		for (int i = 0; i < this.size; i++) {
			Object object = this.storedObjects[i];
			if (object.equals(element)) {
				return i;
			}
		}
		return -1;
	}

	//	/**
	//	 * almost the same as the previous one, but using hashcode explicitly
	//	 * to compare object.
	//	 * 
	//	 * @param element
	//	 * @return
	//	 */
	//	public int indexOf2(Object element) {
	//		if (element == null) {
	//			throw new IllegalArgumentException( "ArrayList cannot contain a null element.");
	//		}
	//		for (int i = 0; i < this.size; i++) {
	//			Object object = this.storedObjects[i];
	//			if ( object == element) {
	//				return i;
	//			}
	//		}
	//		return -1;
	//	}

	/**
	 * Returns the element at the specified position in this list.
	 *  
	 * @param index the position of the desired element.
	 * @return the element stored at the given position
	 * @throws IndexOutOfBoundsException when the index < 0 || index >= size()
	 */
	public Object get(int index) {
		if (index < 0 || index >= this.size) {
			throw new IndexOutOfBoundsException("the index [" + index
					+ "] is not valid for this list with the size [" + this.size + "].");
		}
		return this.storedObjects[index];
	}

	/**
	 * Removes the element at the specified position in this list.
	 *  
	 * @param index the position of the desired element.
	 * @return the element stored at the given position
	 * @throws IndexOutOfBoundsException when the index < 0 || index >= size()
	 */
	public Object remove(int index) {
		if (index < 0 || index >= this.size) {
			throw new IndexOutOfBoundsException("the index [" + index
					+ "] is not valid for this list with the size [" + this.size + "].");
		}
		Object removed = this.storedObjects[index];
		for (int i = index + 1; i < this.size; i++) {
			this.storedObjects[i - 1] = this.storedObjects[i];
		}
		this.size--;
		return removed;
	}

	/**
	 * Removes the given element.
	 * 
	 * @param element the element which should be removed.
	 * @return true when the element was found in this list.
	 * @throws IllegalArgumentException when the given element is null
	 * @see #contains(Object)
	 */
	public boolean remove(Object element) {
		if (element == null) {
			throw new IllegalArgumentException("ArrayList cannot contain null.");
		}
		int index = -1;
		for (int i = 0; i < this.size; i++) {
			Object object = this.storedObjects[i];
			if (object.equals(element)) {
				index = i;
				break;
			}
		}
		if (index == -1) {
			return false;
		}
		for (int i = index + 1; i < this.size; i++) {
			this.storedObjects[i - 1] = this.storedObjects[i];
		}
		this.size--;
		return true;
	}

	//	public boolean remove2( Object element ) {
	//		if (element == null) {
	//			throw new IllegalArgumentException( "ArrayList cannot contain null.");
	//		}
	//		int index = -1;
	//		for (int i = 0; i < this.size; i++) {
	//			Object object = this.storedObjects[i];
	//			if ( object == element) {
	//				index = i;
	//				break;
	//			}
	//		}
	//		if (index == -1) {
	//			return false;
	//		}
	//		for (int i = index+1; i < this.size; i++) {
	//			this.storedObjects[ i-1 ] = this.storedObjects[ i ];
	//		}
	//		this.size--;
	//		return true; 
	//	}

	/**
	 * Removes all of the elements from this list. 
	 * The list will be empty after this call returns. 
	 */
	public void clear() {
		for (int i = 0; i < this.size; i++) {
			this.storedObjects[i] = null;
		}
		this.size = 0;
	}

	/**
	 * Stores the given element in this list.
	 * 
	 * @param element the element which should be appended to this list.
	 * @throws IllegalArgumentException when the given element is null
	 * @see #add( int, Object )
	 */
	public void add(Object element) {
		if (element == null) {
			throw new IllegalArgumentException("ArrayList cannot contain null.");
		}
		if (this.size >= this.storedObjects.length) {
			increaseCapacity();
		}
		this.storedObjects[this.size] = element;
		this.size++;
	}

	/**
	 * Inserts the given element at the defined position.
	 * Any following elements are shifted one position to the back.
	 * 
	 * @param index the position at which the element should be inserted, 
	 * 					 use 0 when the element should be inserted in the front of this list.
	 * @param element the element which should be inserted
	 * @throws IllegalArgumentException when the given element is null
	 * @throws IndexOutOfBoundsException when the index < 0 || index >= size()
	 */
	public void add(int index, Object element) {
		if (element == null) {
			throw new IllegalArgumentException("ArrayList cannot contain null.");
		}
		if (index < 0 || index >= this.size) {
			throw new IndexOutOfBoundsException("the index [" + index
					+ "] is not valid for this list with the size [" + this.size + "].");
		}
		if (this.size >= this.storedObjects.length) {
			increaseCapacity();
		}
		// shift all following elements one position to the back:
		for (int i = this.size; i > index; i--) {
			this.storedObjects[i] = this.storedObjects[i - 1];
		}
		// insert the given element:
		this.storedObjects[index] = element;
		this.size++;
	}

	/**
	 * Replaces the element at the specified position in this list with the specified element. 
	 * 
	 * @param index the position of the element, the first element has the index 0.
	 * @param element the element which should be set
	 * @return the replaced element
	 * @throws IndexOutOfBoundsException when the index < 0 || index >= size()
	 */
	public Object set(int index, Object element) {
		if (index < 0 || index >= this.size) {
			throw new IndexOutOfBoundsException("the index [" + index
					+ "] is not valid for this list with the size [" + this.size + "].");
		}
		Object replaced = this.storedObjects[index];
		this.storedObjects[index] = element;
		return replaced;
	}

	/**
	 * Returns all stored elements as an array.
	 * 
	 * @return the stored elements as an array.
	 */
	public Object[] toArray() {
		Object[] copy = new Object[this.size];
		System.arraycopy(this.storedObjects, 0, copy, 0, this.size);
		return copy;
	}

	/**
	 * Returns all stored elements in the given array.
	 * 
	 * @param target the array in which the stored elements should be copied.
	 * @return the stored elements of this list
	 */
	public Object[] toArray(Object[] target) {
		System.arraycopy(this.storedObjects, 0, target, 0, this.size);
		return target;
	}

	/**
	 * Trims the capacity of this ArrayList instance to be the list's current size. 
	 * An application can use this operation to minimize the storage of an ArrayList instance.
	 */
	public void trimToSize() {
		if (this.storedObjects.length != this.size) {
			Object[] newStore = new Object[this.size];
			System.arraycopy(this.storedObjects, 0, newStore, 0, this.size);
			this.storedObjects = newStore;
		}
	}

	/**
	 * increases the capacity of this list.
	 */
	private void increaseCapacity() {
		int currentCapacity = this.storedObjects.length;
		int newCapacity = currentCapacity + ((currentCapacity * this.growthFactor) / 100);
		if (newCapacity == currentCapacity) {
			newCapacity++;
		}
		Object[] newStore = new Object[newCapacity];
		System.arraycopy(this.storedObjects, 0, newStore, 0, this.size);
		this.storedObjects = newStore;
	}

	public boolean isEmpty() {
		return (size <= 0);
	}

	//#ifdef debug
	public static void main(String[] args) {
		try {
			ArrayList a = new ArrayList();
			a.add("abc");
			a.get(1);
		} catch (Exception ex) {
			ex.printStackTrace();
		}
	}
	//#endif
}