List区别
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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
