黑马集合学习 自定义ArrayList01

package demo;

import java.util.Arrays;

public class MyArrayList<T> {
    Object[] t;
    int size;
    private static final int MAX_ARRAY_SIZE = 5;
    private static final Object[] EMPTY_ELEMENTDATA = {};

    public MyArrayList(){
        //必须给t赋值，不然每次都必须判断t是否为null，影响效率
        t = EMPTY_ELEMENTDATA;
    }

    public boolean add(T e){
        //必须给t赋值，不然每次都必须在这里判断t是否为null，影响效率
        if(t.length == size){
            grow(size + 1);
        }
        t[size++] = e;
        return true;
    }

    private void grow(int minCapacity) {
        int newCapacity = t.length + t.length >> 1;
        //minCapacity溢出
        if(minCapacity < 0)
            throw new RuntimeException();
        //newCapacity < minCapacity必须加，因为刚开始时newCapacity增长小于minCapacity
        if(newCapacity < minCapacity || newCapacity < 0 || newCapacity > MAX_ARRAY_SIZE){
            if(minCapacity > MAX_ARRAY_SIZE){
                throw new RuntimeException();
            }else{
                //生长到最大
                t = Arrays.copyOf(t, MAX_ARRAY_SIZE);
            }
        }else{
            //生长到newCapacity
            t = Arrays.copyOf(t, newCapacity);
        }
    }
}