java学习之旅59--模拟ArrayList容器的底层实现_JDK源码分析ArrayList

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模拟ArrayList

package cn.itcast.java.test;/** * 模拟ArrayList * @author Administrator * */public class MyArrayList {private Object[] value;private int size;public MyArrayList(){//value = new Object[10];this(10);}public MyArrayList(int capacity){value = new Object[capacity];}/* * 返回容器的大小 */public int size(){return size;}/* * 判断容器是否为空 */public boolean isEmpty(){return value.length == 0;}/* * 添加元素 */public void add(Object obj){value[size] = obj;size++;if(size>=value.length){//扩容int newCapacity = value.length*2+2;Object[] newValue = new Object[newCapacity];//数组拷贝for(int i=0;i<value.length;i++){newValue[i] = value[i];}value = newValue;}}/* * 根据索引返回元素 */public Object get(int index){if(index<0||index>=value.length){try {throw new Exception();} catch (Exception e) {e.printStackTrace();}}return value[index];}public static void main(String[] args) {MyArrayList list = new MyArrayList();list.add("aa");list.add(new Person("Gao"));list.add(11);System.out.println(list.get(0));System.out.println(list.get(1));System.out.println(list.size());System.out.println(list.isEmpty());}}

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