ArrayList13.java

public abstract class AbstractList<E> extends AbstractCollection<E> implements List<E> {
    protected AbstractList()  =>　空方法
    public boolean add(E e)  => 调用含有index的add
    abstract public E get(int index) => 未实现
    public E set(int index, E element) => 抛出异常
    public void add(int index, E element) => 抛出异常
    public E remove(int index) => 抛出异常
    public int indexOf(Object o) => 调用ListIterator进行查找
    public int lastIndexOf(Object o) => 调用ListIterator进行查找
    public void clear() => 调用RemoveRange
    public boolean addAll(int index, Collection<? extends E> c) => 循环调用add
    public Iterator<E> iterator() => 返回Itr()实例
    public ListIterator<E> listIterator() => 返回ListIterator实例
    public ListIterator<E> listIterator(final int index) => 返回ListIterator实例（边界检查）
    private class Itr implements Iterator<E> => 一系列Iterator操作，next()用AbstractList.get实现，remove()用AbstractList.remove实现
    private class ListItr extends Itr implements ListIterator<E> => 加强版Iterator。均调用AbstractList中的方法实现。
    public List<E> subList(int fromIndex, int toIndex) {
        return (this instanceof RandomAccess ?
                new RandomAccessSubList<>(this, fromIndex, toIndex) :
                new SubList<>(this, fromIndex, toIndex));
    }
    public boolean equals(Object o) {
        if (o == this)
            return true;
        if (!(o instanceof List))
            return false;

        ListIterator<E> e1 = listIterator();
        ListIterator e2 = ((List) o).listIterator();
        while (e1.hasNext() && e2.hasNext()) {
            E o1 = e1.next();
            Object o2 = e2.next();
            if (!(o1==null ? o2==null : o1.equals(o2)))
                return false;
        }
        return !(e1.hasNext() || e2.hasNext());
    }

    public int hashCode() {
        int hashCode = 1;
        for (E e : this)
            hashCode = 31*hashCode + (e==null ? 0 : e.hashCode());
        return hashCode;
    }

    protected void removeRange(int fromIndex, int toIndex) => 调用Iterator.remove()方法

    protected transient int modCount = 0;

    private void rangeCheckForAdd(int index) => RangeCheck

class SubList<E> extends AbstractList<E> => 一切关于sublist的东西

class RandomAccessSubList<E> extends SubList<E> implements RandomAccess {
    RandomAccessSubList(AbstractList<E> list, int fromIndex, int toIndex) {
        super(list, fromIndex, toIndex);
    }

    public List<E> subList(int fromIndex, int toIndex) {
        return new RandomAccessSubList<>(this, fromIndex, toIndex);
    }
}