java实现泛型动态数组源码小分享

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package com.xmonster.demo2;

import java.util.Arrays;

public class DynamicArray<E> {

    private static final int DEFAULT_CAPACITY = 10;
    private int size;
    private Object[] elementData;
    public DynamicArray(){
        this.elementData = new Object[DEFAULT_CAPACITY];
    }

    private void ensureCapacity(int minCapacity){
        int oldCapacity = elementData.length;
        if(oldCapacity >= minCapacity){
            return;
        }
        int newCapacity = oldCapacity * 2;
        if(newCapacity < minCapacity){
            newCapacity  =minCapacity;
        }
        elementData = Arrays.copyOf(elementData, newCapacity);

    }
    public void add(E e){
        ensureCapacity(size+1);
        elementData[size++]=e;

    }
    public E get(int index){
        return (E)elementData[index];
    }
    public int size(){
        return size;
    }

    public E set(int index, E element){
        E oldValue = get(index);
        elementData[index] = element;
        return oldValue;
    }
    
}