Array数组

 public void add(int index, E e) {
        if (size == data.length)
            throw new IllegalArgumentException("array list is full");
        if (index < 0 || index > size) {
            throw new IllegalArgumentException("add error");
        }
        for (int i = size - 1; i >= index; i--) {
            data[i + 1] = data[i];
        }
        data[index] = e;
        size++;
    }

public void resize(int newCapcity){
        E[] newData =(E[])new Object[newCapcity];
        for(int i = 0;i<size;i++){
            newData[i] = data[i];
        }
        data = newData;
    }