java - JCIP 书中定义的 core java 内部 protected 对象的示例

Question

JCIP将 protected 对象定义为:

Guarded. A guarded object can be accessed only with a specific lock held. Guarded objects include those that are encapsulated within other thread-safe objects and published objects that are known to be guarded by a specific lock.

哪个可以作为核心 Java 内部此类对象的示例？

Answer 1

我立即想到的是 Collections.synchronizedList() 返回的 SynchronizedList 实例所保存的列表。这是其源代码的一部分:

static class SynchronizedList<E>
    extends SynchronizedCollection<E>
    implements List<E> {

    final List<E> list;

    public boolean equals(Object o) {
        synchronized (mutex) {return list.equals(o);}
    }
    public int hashCode() {
        synchronized (mutex) {return list.hashCode();}
    }

    public ListIterator<E> listIterator() {
        return list.listIterator(); // Must be manually synched by user
    }

list 对象不是线程安全的，但由互斥体保护。 listIterator() 返回的对象应该由相同的互斥体(即同步列表本身)手动保护