java中List接口与实现类介绍

        List list =  new ArrayList();
        for(int i = 0; i < 10; i++) {
            list.add(1);
        }

    public ArrayList() {
        this.elementData = DEFAULTCAPACITY_EMPTY_ELEMENTDATA;
    }
    private static final Object[] DEFAULTCAPACITY_EMPTY_ELEMENTDATA = {};

    public boolean add(E e) {
        ensureCapacityInternal(size + 1);  // Increments modCount!!
        elementData[size++] = e;
        return true;
    }

    private void ensureCapacityInternal(int minCapacity) {
        if (elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA) {
            minCapacity = Math.max(DEFAULT_CAPACITY, minCapacity); //（10，1）
        }

        ensureExplicitCapacity(minCapacity);
    }

    private void ensureExplicitCapacity(int minCapacity) {
        modCount++; //记录当前集合被修改的次数

        // overflow-conscious code
        if (minCapacity - elementData.length > 0) 
            grow(minCapacity);
    }

    private void grow(int minCapacity) {
        // overflow-conscious code
        int oldCapacity = elementData.length;
        int newCapacity = oldCapacity + (oldCapacity >> 1); //扩容为1.5倍
        if (newCapacity - minCapacity < 0) //newCapacity=0 第一次的时候执行
            newCapacity = minCapacity;
        if (newCapacity - MAX_ARRAY_SIZE > 0)
            newCapacity = hugeCapacity(minCapacity);
        // minCapacity is usually close to size, so this is a win:
        elementData = Arrays.copyOf(elementData, newCapacity);
    }