程序代码：

public class test {
    Object[] obj;
    int size;
    
    public int size() {
        return size;
    }
    
    public test() {
        this.test(5);
    }
    private void test(int i) {
        obj = new Object[i];
    }
    public void add(Object o) {
        
        if (size==obj.length) {
            grow();
        }
        
        obj[size] = o;
        size++;
    }
    private void grow() {
        Object[] o = new Object[obj.length+10];
        
        for(int i=0;i<size;i++){
            o[i] = obj[1];
        }
        obj=o;
    }
    public Object get(int i) {

        return obj[i];
    }
    
    public void set(int i,Object o) {
        // TODO Auto-generated method stub
        for(int j=size;j>i;j--){
            obj[j]=obj[j-1];
        }
        obj[i] = o;
    }