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并发容器-List

并发容器-List

作者: zhaoyunxing | 来源:发表于2017-08-22 20:46 被阅读0次

List区别

  • CopyOnWriteArrayList

    原理:在添加/修改时,先对当前容器复制一份,然后新的容器里添加元素,添加完元素之后,再将原容器的引用指向新的容器

    *写的速度特别慢,但是读的速度特别快,同时又是线程安全

             /**
              * Appends the specified element to the end of this list.
              *
              * @param e element to be appended to this list
              * @return {@code true} (as specified by {@link Collection#add})
              */
             public boolean add(E e) {
                 final ReentrantLock lock = this.lock;
                 lock.lock();
                 try {
                     Object[] elements = getArray();
                     int len = elements.length;
                     Object[] newElements = Arrays.copyOf(elements, len + 1);
                     newElements[len] = e;
                     setArray(newElements);
                     return true;
                 } finally {
                     lock.unlock();
                 }
             }
    
  • ArrayList
    *线程不安全,但是效率高

  • Vector
    *读写都加了锁,线程安全,但是速度慢

           
                /**
                 * Appends the specified element to the end of this Vector.
                 *
                 * @param e element to be appended to this Vector
                 * @return {@code true} (as specified by {@link Collection#add})
                 * @since 1.2
                 */
                public synchronized boolean add(E e) {
                    modCount++;
                    ensureCapacityHelper(elementCount + 1);
                    elementData[elementCount++] = e;
                    return true;
                }
    

源码:github 欢迎各位同学指出问题/建议

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