copyOnWriteArray 并发包下的不安全(数组)集合

package java.util.concurrent;//你没有看错,是这个包

 private transient volatile Object[] array;//初始化数组

 public CopyOnWriteArrayList() {//构造函数,初始化
        setArray(new Object[0]);
    }

 final void setArray(Object[] a) {
        array = a;
    }

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();
        }
    }

final Object[] getArray() {
        return array;
    }

public E get(int index) {//获取单个数组对象
        return get(getArray(), index);
    }

private E get(Object[] a, int index) {
        return (E) a[index];
    }