Bag的实现续

Bag的实现续，实现了迭代的功能

package com.woxiaoe.collection;

import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

public class EBag<T> implements Collection<T>{
	private int bagSize = 0;//大小
	private T[] bagArray;//数组
	
	public EBag(int capacity) {
		bagArray = (T[]) new Object[capacity];
	}
	
	/**
	 * 添加一个对象，如果bag已经满了，者返回false
	 */
	public boolean add(T e) {
		if(size() < bagArray.length){
			bagArray[bagSize ++ ] = e;
			return true;
		}
		return false;
	}

	@Override
	public boolean addAll(Collection<? extends T> c) {
		//容量超出 返回fase
		boolean flag = false;
		for (Iterator iterator = c.iterator(); iterator.hasNext();) {
			T t = (T) iterator.next();
			flag = true;
			add(t);
		}
		return flag;
	}

	@Override
	public void clear() {
		bagSize = 0;
		
	}

	@Override
	public boolean contains(Object o) {
		for(int i = 0; i < bagSize; i++){
			if(bagArray[i].equals(o)){
				return true;
			}
		}
		return false;
	}

	@Override
	public boolean containsAll(Collection<?> c) {
		for (Iterator iterator = c.iterator(); iterator.hasNext();) {
			Object object = (Object) iterator.next();
			if(!contains(object)){
				return false;
			}
		}
		return true;
	}

	@Override
	public boolean isEmpty() {
		
		return bagSize == 0?false:true;
	}

	@Override
	public Iterator<T> iterator() {
		return new Iteratorimpl();
	}

	@Override
	public boolean remove(Object o) {
		for(int i = 0; i < bagSize; i++){
			if(bagArray[i].equals(o)){
				remove(i);
				return true;
			}
		}
		return false;
	}
	public boolean remove(int index){
		if(index >= size()){
			return false;
		}
		for(int i = index;i<size() - 1;i++){
			bagArray[i] = bagArray[i+1];
		}
		bagSize -=1;
		return true;
	}
	@Override
	public boolean removeAll(Collection<?> c) {
		boolean flag = false;
		for (Iterator iterator = c.iterator(); iterator.hasNext();) {
			Object object = (Object) iterator.next();
			if(remove(object)){
				flag = true;
			}
		}
		return flag;
	}

	@SuppressWarnings("unchecked")
	@Override
	public boolean retainAll(Collection<?> c) {
		boolean flag = false;
		T[] newArray = (T[]) new Object[bagSize];
		int index = 0;
		for(int i = 0; i < bagSize; i++){
			if(c.contains(bagArray[i])){//如果不包含这个元素，删除
				newArray[index ++] = bagArray[i];
				flag = true;
			}
		}
		if(flag){
			bagArray = newArray;
			bagSize = index;
		}
		return flag;
	}

	@Override
	public int size() {
		return bagSize;
	}

	@Override
	public Object[] toArray() {
		Object[] array = new Object[bagSize];
		System.arraycopy(bagArray, 0, array, 0, bagSize);
		return array;
	}

	@Override
	public <T> T[] toArray(T[] a) {
		T[] array = (T[]) new Object[bagSize];
		System.arraycopy(bagArray, 0, array, 0, bagSize);
		return array;
	}
	public void addAll(T[] array){
		int len = array.length;
		for (int i = 0; i < len; i++) {
			T t = array[i];
			add(t);
		}
	}
	@Override
	public String toString() {
		StringBuffer str = new StringBuffer("");
		if(this == null){
			return "null";
		}
		if(size() == 0){
			return "[]";
		}
		str.append("[" + bagArray[0]);
		for(int i = 1; i < bagSize; i++){
			str.append("," + bagArray[i]);
		}
		str.append("]");
		return str.toString();
	}
	/**
	 * 合并
	 * @param <T>
	 * @param bag1
	 * @param bag2
	 * @return
	 */
	public static <T> EBag<T> union(EBag<T> bag1,EBag<T>bag2){
		EBag<T> unionBag = new EBag<T>(bag1.size() + bag2.size());//
		T[] array = (T[]) new Object[bag1.size() + bag2.size()];
		System.arraycopy(bag1.toArray(), 0, array, 0, bag1.size());
		System.arraycopy(bag2.toArray(), 0, array, bag1.size(), bag2.size());
		unionBag.addAll(array);
		return unionBag;
	}
	/**
	 * 求交集
	 * @param <T>
	 * @param bag1
	 * @param bag2
	 * @return
	 */
	public static <T> EBag<T> intersection(EBag<T> bag1,EBag<T>bag2){
		EBag<T> intersectionBag = new EBag<T>(bag1.size()>= bag2.size()?bag2.size():bag1.size());//以bag1 和 bag2中大的值为新数组长度
		Set<T> set = new HashSet<T>();
		T[] array1 = (T[]) bag1.toArray();
		T[] array2 = (T[])bag2.toArray();
		int a1 = array1.length;
		int a2 = array2.length;
		for(int i = 0; i < a1; i++){
			set.add(array1[i]);
		}
		for(int i = 0; i < a2; i++){
			if(set.contains(array2[i])){//相同存入集合
				intersectionBag.add(array2[i]);
			}
		}
		return intersectionBag;
	}
	/**
	 * bag1 - bag2
	 * @param <T>
	 * @param bag1
	 * @param bag2
	 * @return
	 */
	public static <T> EBag<T> difference(EBag<T> bag1,EBag<T> bag2){
		EBag<T> differentBag = new EBag<T>(bag1.size() > bag2.size()?bag1.size():bag2.size());
		Set<T> set = new HashSet<T>();
		T[] array1 = (T[]) bag1.toArray();
		T[] array2 = (T[])bag2.toArray();
		differentBag.addAll(array1);
		int a1 = array1.length;
		int a2 = array2.length;
		for(int i = 0; i < a1; i++){
			set.add(array1[i]);
		}
		for(int i = 0; i < a2; i++){
			if(set.contains(array2[i])){//取出bag1中和bge2相同的
				differentBag.remove(array2[i]);
			}
		}
		return differentBag;
	}
	
	private  class Iteratorimpl implements Iterator<T>{
		private int nextIndex = 0;//下一个元素的标记
		private int latestIndex = -1;//最流行元素的下标
		@Override
		public boolean hasNext() {
			return nextIndex != bagSize;
		}

		@Override
		public T next() {
			latestIndex = nextIndex;
			nextIndex ++;
			return bagArray[latestIndex];
		}

		@Override
		public void remove() {
			if( latestIndex == -1){
				throw new RuntimeException("删除出错");
			}
			EBag.this.remove(bagArray[latestIndex]);
			latestIndex = -1;
			nextIndex --;
		}
		
	}
}