package com.coding.basic;
import java.util.Arrays;
import java.util.LinkedList;
/**
* @author hugaoqing
* created on 2017-3-8
*/
public class ArrayList implements List {
private int size = 0;
private Object[] elementData = new Object[3];
/*
* 添加元素
*
*/
public void add(Object o){
/*if(elementData.length == size){
Object[] buffer = new Object[size+15];
System.arraycopy(elementData, 0, buffer, 0, size);
elementData = buffer;
elementData[size] = o;
size++;
}else {
elementData[size] = o;
size++;
}*/
add(size, o);
}
/*
*
* 指定位置添加元素
*/
public void add(int index, Object o){
if(index <0 || index > size){
throw new IndexOutOfBoundsException();
}
if(size+1<elementData.length){
Object [] newArr = new Object[size-index+1];
newArr[0] = o;
System.arraycopy(elementData, index, newArr, 1, size-index);
System.arraycopy(newArr, 0, elementData, index, size-index+1);
size++;
}else{
Object[] buffer = new Object[(size*3)/2+1];
System.arraycopy(elementData, 0, buffer, 0, size);
elementData = buffer;
Object [] newArr = new Object[size-index+1];
newArr[0] = o;
System.arraycopy(elementData, index, newArr, 1, size-index);
System.arraycopy(newArr, 0, elementData, index, size-index+1);
size++;
}
}
public Object get(int index){
if(index<0||index>=size){
throw new IndexOutOfBoundsException();
}
return elementData[index];
}
public Object remove(int index){
if(index<0||index>=size){
throw new IndexOutOfBoundsException();
}
Object out = elementData[index];
Object[] temp = new Object[size-index-1];
System.arraycopy(elementData, index+1, temp, 0, size-index-1);
System.arraycopy(temp, 0, elementData,index, size-index-1);
//将移除的元素的指针去掉，避免内存泄漏
elementData[size-1] = null;
size--;
return out;
}
public int size(){
return this.size;
}
@Override
public String toString() {
Object[] objs = new Object[size];
System.arraycopy(elementData, 0,objs , 0, size);
return Arrays.toString(objs);
}
public Iterator iterator(){
return new Iterator() {
int cursor = 0;
public Object next() throws Exception {
cursor++;
return get(cursor-1);
}
public boolean hasNext() {
return this.cursor<size();
}
};
}
public static void main(String[] args) throws Exception {
List list = new ArrayList();
list.add(1);
list.add(2);
list.add(3);
list.add(3,4);
System.out.println(list);
list.add(0,0);
System.out.println(list);
Iterator itr = list.iterator();
while(itr.hasNext()){
System.out.println(itr.next());
}
}
}