java - 地图内

Question

我有一个以下代码来测试GC存储在地图中的弱引用。

    public static void main(String[] args) {
    Map<String, WeakReference<Person>> map = new HashMap<String, WeakReference<Person>>();

    for (int i = 0; i < 5000; i++) {
        Person person = new Person("weak_id"+ i, "hello"+ i, "smith"+ i, "hello@hotmail.com"+ i);
        map.put("id"+i, new WeakReference(person));
        person = null;
    }

    Map<String, Person> cache = new HashMap<String, Person>();
    for (int i = 0; i < 9000; i++) {
        Person person = new Person("id"+ i, "hello"+ i, "smith"+ i, "hello@hotmail.com"+ i);
        cache.put("id"+i, person);
    }

    // Make a breakpoint here and perform 'Perform GC' on the jconsole
    // and let the following code continue to see if it is discarded by GC
    for (int i = 0; i < 5000; i++) {
        WeakReference ref = map.get("id"+i);
        if (ref == null || ref.get() == null) {
            continue;
        }
        System.out.println(ref.get());
    }

    for (int i = 50001; i < 10000; i++) {
        Person person = new Person("later_id"+ i, "hello"+ i, "smith"+ i, "hello@hotmail.com"+ i);
        map.put("later_id"+i, new WeakReference(person));
    }

    System.out.println("hello");

}

我试图找出GC是否实际上回收了为地图存储分配的内存5000 WeakReference引用Person实例。我将'finalize'方法添加到Person对象中，并在GC启动时打印出每个实例变量的值，以便我可以看到GC启动。

当我在jconsole上触发'Perform GC'时，我看到了打印输出消息。我猜这意味着GC回收为50000 Person实例分配的内存。

但是在Eclipse调试模式下，即使存储在地图中的WeakReferences似乎是垃圾收集的，我仍然看到5000的大小而不是空地图。

是否意味着即使GC丢弃了5000个人实例，HashMap仍然在地图中保留了5000个空格吗？