package com.anxpp.designpattern.iterator;

import java.util.Arrays;

//方便演示而实现的简陋的数组list

public class MyArrayList<T> implements MyList<T>{

private int size; //存放的元素个数,会默认初始化为0

private Object[] defaultList; //使用数组存放元素

private static final int defaultLength = 10;//默认长度

public MyArrayList(){ //默认构造函数

defaultList = new Object[defaultLength];

}

@Override

public MyIterator<T> iterator() {

return new Iterator();

}

//大小自动增长

private void ensureCapacity(int capacity){

int nowLength = defaultList.length;

if(capacity >= nowLength){

nowLength = nowLength + (nowLength>>1);

if(nowLength<0)//溢出

nowLength = Integer.MAX_VALUE;

defaultList = Arrays.copyOf(defaultList, nowLength);

}

}

//添加元素

@Override

public boolean add(T t) {

ensureCapacity(size+1);

defaultList[size++] = t;

return true;

}

//获取元素

@SuppressWarnings("unchecked")

@Override

public T get(int index) {

if(index<0 || index>=size) return null;

return (T) defaultList[index];

}

@Override

public T remove() {

return remove(size-1);

}

@SuppressWarnings("unchecked")

@Override

public T remove(int index) {

if(index<0||index>=size) return null;

T element = (T) defaultList[index];

if(index != size-1)

System.arraycopy(defaultList, index+1, defaultList, index,size-index-1);

size--;

return element;

}

@Override

public boolean remove(T element) {

if(element==null){

for(int i = 0 ; i<size;i++)

if(defaultList[i]==null){

System.arraycopy(defaultList, i+1, defaultList, i,size-i-1);

size--;

return true;

}

}

else{

for(int i = 0 ; i<size;i++)

if(defaultList[i].equals(element)){

System.arraycopy(defaultList, i+1, defaultList, i,size-i-1);

size--;

return true;

}

}

return false;

}

@Override

public boolean set(int index,T element) {

if(index<0||index>=size) return false;

defaultList[index] = element;

return true;

}

@Override

public int size() {

return size;

}

//迭代器

private class Iterator implements MyIterator<T>{

private int next;

@Override

public boolean hasNext() {

return next<size;

}

@SuppressWarnings("unchecked")

@Override

public T next() {

return (T) defaultList[next++];

}

@Override

public T remove() {

// TODO Auto-generated method stub

return null;

}

}

}