LinkedList实现 - Deque 方法

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Deque 方法

1. 
   
2.     /**
   
3.      * Inserts the specified element at the front of this list.
   
4.      *
   
5.      * @param e the element to insert
   
6.      * @return {@code true} (as specified by {@link Deque#offerFirst})
   
7.      * @since 1.6
   
8.      */
   
9.     public boolean offerFirst(E e) {
   
10.         addFirst(e);
    
11.         return true;
    
12.     }
    
13. 
    
14.     /**
    
15.      * Inserts the specified element at the end of this list.
    
16.      *
    
17.      * @param e the element to insert
    
18.      * @return {@code true} (as specified by {@link Deque#offerLast})
    
19.      * @since 1.6
    
20.      */
    
21.     public boolean offerLast(E e) {
    
22.         addLast(e);
    
23.         return true;
    
24.     }
    
25. 
    
26.     /**
    
27.      * Retrieves, but does not remove, the first element of this list,
    
28.      * or returns {@code null} if this list is empty.
    
29.      *
    
30.      * @return the first element of this list, or {@code null}
    
31.      *         if this list is empty
    
32.      * @since 1.6
    
33.      */
    
34.     public E peekFirst() {
    
35.         final Node<E> f = first;
    
36.         return (f == null) ? null : f.item;
    
37.      }
    
38. 
    
39.     /**
    
40.      * Retrieves, but does not remove, the last element of this list,
    
41.      * or returns {@code null} if this list is empty.
    
42.      *
    
43.      * @return the last element of this list, or {@code null}
    
44.      *         if this list is empty
    
45.      * @since 1.6
    
46.      */
    
47.     public E peekLast() {
    
48.         final Node<E> l = last;
    
49.         return (l == null) ? null : l.item;
    
50.     }
    
51. 
    
52.     /**
    
53.      * Retrieves and removes the first element of this list,
    
54.      * or returns {@code null} if this list is empty.
    
55.      *
    
56.      * @return the first element of this list, or {@code null} if
    
57.      *     this list is empty
    
58.      * @since 1.6
    
59.      */
    
60.     public E pollFirst() {
    
61.         final Node<E> f = first;
    
62.         return (f == null) ? null : unlinkFirst(f);
    
63.     }
    
64. 
    
65.     /**
    
66.      * Retrieves and removes the last element of this list,
    
67.      * or returns {@code null} if this list is empty.
    
68.      *
    
69.      * @return the last element of this list, or {@code null} if
    
70.      *     this list is empty
    
71.      * @since 1.6
    
72.      */
    
73.     public E pollLast() {
    
74.         final Node<E> l = last;
    
75.         return (l == null) ? null : unlinkLast(l);
    
76.     }
    
77. 
    
78.     /**
    
79.      * Pushes an element onto the stack represented by this list.  In other
    
80.      * words, inserts the element at the front of this list.
    
81.      *
    
82.      * <p>This method is equivalent to {@link #addFirst}.
    
83.      *
    
84.      * @param e the element to push
    
85.      * @since 1.6
    
86.      */
    
87.     public void push(E e) {
    
88.         addFirst(e);
    
89.     }
    
90. 
    
91.     /**
    
92.      * Pops an element from the stack represented by this list.  In other
    
93.      * words, removes and returns the first element of this list.
    
94.      *
    
95.      * <p>This method is equivalent to {@link #removeFirst()}.
    
96.      *
    
97.      * @return the element at the front of this list (which is the top
    
98.      *         of the stack represented by this list)
    
99.      * @throws NoSuchElementException if this list is empty
    
100.      * @since 1.6
     
101.      */
     
102.     public E pop() {
     
103.         return removeFirst();
     
104.     }
     
105. 
     
106.     /**
     
107.      * Removes the first occurrence of the specified element in this
     
108.      * list (when traversing the list from head to tail).  If the list
     
109.      * does not contain the element, it is unchanged.
     
110.      *
     
111.      * @param o element to be removed from this list, if present
     
112.      * @return {@code true} if the list contained the specified element
     
113.      * @since 1.6
     
114.      */
     
115.     public boolean removeFirstOccurrence(Object o) {
     
116.         return remove(o);
     
117.     }
     
118. 
     
119.     /**
     
120.      * Removes the last occurrence of the specified element in this
     
121.      * list (when traversing the list from head to tail).  If the list
     
122.      * does not contain the element, it is unchanged.
     
123.      *
     
124.      * @param o element to be removed from this list, if present
     
125.      * @return {@code true} if the list contained the specified element
     
126.      * @since 1.6
     
127.      */
     
128.     public boolean removeLastOccurrence(Object o) {
     
129.         if (o == null) {
     
130.             for (Node<E> x = last; x != null; x = x.prev) {
     
131.                 if (x.item == null) {
     
132.                     unlink(x);
     
133.                     return true;
     
134.                 }
     
135.             }
     
136.         } else {
     
137.             for (Node<E> x = last; x != null; x = x.prev) {
     
138.                 if (o.equals(x.item)) {
     
139.                     unlink(x);
     
140.                     return true;
     
141.                 }
     
142.             }
     
143.         }
     
144.         return false;
     
145.     }
     

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原文链接：https://pdai.tech/md/java/collection/java-collection-LinkedList.html