arraylist.java

整理的3G视线常用工具整理。里面包含了大量有用的代码

 
package com.gggeye.util;

 
public class ArrayList {
	private Object[] storedObjects;
	private int growthFactor;
	private int size;
	
	 
	public ArrayList() {
		this( 10, 75 );
	}
	
	 
	public ArrayList( int initialCapacity ) {
		this( initialCapacity, 75 );
	}
 
	public ArrayList( int initialCapacity, int growthFactor ) {
		this.storedObjects = new Object[ initialCapacity ];
		this.growthFactor = growthFactor;
	}
 
	public int size() {
		return this.size;
	}
	
	 
	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;
	}
	
	 
	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;
	}
	
	 
	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 ];
	}
		
	 
	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; 
	}
	
	 
	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 void clear() {
		for (int i = 0; i < this.size; i++) {
			this.storedObjects[i] = null;
		}
		this.size = 0;
	}

	 
	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++;
	}
	 
	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++;
	}
	
	 
	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;
	}
	
	 
	public Object[] toArray() {
		Object[] copy = new Object[ this.size ];
		System.arraycopy( this.storedObjects, 0, copy, 0, this.size );
		return copy;
	}
	
	 
	public Object[] toArray( Object[] target ) {
		System.arraycopy( this.storedObjects, 0, target, 0, this.size );
		return target;
	}
	
	 
	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;
		}
	}
	
 
	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;
	}


}