Array的基本操作

public class Array<E> {
    private E[] data;
    private int size;
    public Array(int capacity){
        data=(E[])new Object[capacity];
        size=0;
    }
    public Array(){
        this(10);
    }
    public int getSize(){
        return size;
    }
    public int getCapacity(){
        return data.length;
    }
    public boolean isEmpty(){
        return size==0;
    }
    public void add(int index,E e){

        if (index<0||index>size)
            throw new IllegalArgumentException("add failed");
        if (size==data.length)
           resize(2*data.length);
        for (int i=size-1;i>=index;i--)
            data[i+1]=data[i];
        data[index]=e;
        size++;
    }
    private void resize(int capacity){
        E[] newData=(E[])new Object[capacity];
        for (int i = 0; i <size ; i++)
            newData[i]=data[i];
        data=newData;
    }
    public void addFirst(E e){
        this.add(0,e);
    }
    public void addLast(E e){
        this.add(size,e);
    }
    @Override
    public String toString(){
        StringBuilder res=new StringBuilder();
        res.append(String.format("Array size=%d,capacity=%d\n",size,data.length));
        res.append("[");
        for (int i = 0; i <size ; i++) {
            res.append(data[i]);
            if (i!=size-1)
                res.append(",");
        }
        res.append("]");
        return res.toString();
    }
    E get(int index){
        if (index<0||index>=size)
            throw new IllegalArgumentException("add failed");
        return data[index];
    }
    void set(int index,E e){
        if (index<0||index>=size)
            throw new IllegalArgumentException("add failed");
        data[index]=e;
        return;
    }
    public boolean contains(E e){
        for (int i = 0; i <size ; i++) {
            if (data[i]==e)
                return true;
        }
        return false;
    }
    public int find(E e){
        for (int i = 0; i <size ; i++) {
            if (data[i]==e)
                return i;
        }
        return -1;
    }
    public E remove(int index){
        if (index<0||index>=size)
            throw new IllegalArgumentException("remove failed");
        E e=data[index];
        for (int i = index+1; i <size ; i++) {
            data[i-1]=data[i];
        }
        size--;
        if (size==data.length/2){
            resize(data.length/4);
        }
        return e;
    }
    public E removeFIrst(){
        return remove(0);
    }
    public E removeLast(){
        return remove(size-1);
    }
    public void removeElement(E e){
        int index=find(e);
        if (index!=-1)
            remove(index);
    }

}