其他 源码解析 https://blog.csdn.net/qq_32726809/article/category/8035214

3.14indexOf(Object o)

找见对象的位置，用到equals方法，利用for循环，新颖的用法！

[code]  public int indexOf(Object o) {
int index = 0;
if (o == null) {
for (Node<E> x = first; x != null; x = x.next) {
if (x.item == null)
return index;
index++;
}
} else {
for (Node<E> x = first; x != null; x = x.next) {
if (o.equals(x.item))
return index;
index++;
}
}
return -1;
}

peek()

获取第一个元素

[code] public E peek() {
final Node<E> f = first;
return (f == null) ? null : f.item;
}

poll()

检索和删除第一个元素

[code] public E poll() {
final Node<E> f = first;
return (f == null) ? null : unlinkFirst(f);
}

其他简单方法

[code]  public boolean offer(E e) {
return add(e);
}

public boolean offerFirst(E e) {
addFirst(e);
return true;
}

public boolean offerLast(E e) {
addLast(e);
return true;
}

public E peekFirst() {
final Node<E> f = first;
return (f == null) ? null : f.item;
}

public E peekLast() {
final Node<E> l = last;
return (l == null) ? null : l.item;
}

public E pollFirst() {
final Node<E> f = first;
return (f == null) ? null : unlinkFirst(f);
}

public E pollLast() {
final Node<E> l = last;
return (l == null) ? null : unlinkLast(l);
}

public void push(E e) {
addFirst(e);
}

public E pop() {
return removeFirst();
}

public boolean removeFirstOccurrence(Object o) {
return remove(o);
}

可以看出，不管方法名怎么变，用的都是 （一）中所说的方法

removeLastOccurrence(Object o)

• 移除最后出现的这个元素

这个方法其实就是从后往前遍历，找到最后一个元素，移除

[code] public boolean removeLastOccurrence(Object o) {
if (o == null) {
for (Node<E> x = last; x != null; x = x.prev) {
if (x.item == null) {
unlink(x);
return true;
}
}
} else {
for (Node<E> x = last; x != null; x = x.prev) {
if (o.equals(x.item)) {
unlink(x);
return true;
}
}
}
return false;
}

toArray()

将数组转为字符串

[code]public Object[] toArray() {
Object[] result = new Object[size];
int i = 0;
for (Node<E> x = first; x != null; x = x.next)
result[i++] = x.item;
return result;
}

内部类

ListItr

这个内部类实现了迭代器，由于其实现了ListIterator，因此前后都可以遍历。

[code]    private class ListItr implements ListIterator<E> {
private Node<E> lastReturned;
private Node<E> next;
private int nextIndex;
private int expectedModCount = modCount;

ListItr(int index) {
// assert isPositionIndex(index);
next = (index == size) ? null : node(index);
nextIndex = index;
}

public boolean hasNext() {
return nextIndex < size;
}

public E next() {
checkForComodification();
if (!hasNext())
throw new NoSuchElementException();

lastReturned = next;
next = next.next;
nextIndex++;
return lastReturned.item;
}

public boolean hasPrevious() {
return nextIndex > 0;
}

public E previous() {
checkForComodification();
if (!hasPrevious())
throw new NoSuchElementException();

lastReturned = next = (next == null) ? last : next.prev;
nextIndex--;
return lastReturned.item;
}

public int nextIndex() {
return nextIndex;
}

public int previousIndex() {
return nextIndex - 1;
}

public void remove() {
checkForComodification();
if (lastReturned == null)
throw new IllegalStateException();

Node<E> lastNext = lastReturned.next;
unlink(lastReturned);
if (next == lastReturned)
next = lastNext;
else
nextIndex--;
lastReturned = null;
expectedModCount++;
}

public void set(E e) {
if (lastReturned == null)
throw new IllegalStateException();
checkForComodification();
lastReturned.item = e;
}

public void add(E e) {
checkForComodification();
lastReturned = null;
if (next == null)
linkLast(e);
else
linkBefore(e, next);
nextIndex++;
expectedModCount++;
}

public void forEachRemaining(Consumer<? super E> action) {
Objects.requireNonNull(action);
while (modCount == expectedModCount && nextIndex < size) {
action.accept(next.item);
lastReturned = next;
next = next.next;
nextIndex++;
}
checkForComodification();
}

final void checkForComodification() {
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
}
}