範例
protected void finalize() throws Throwable {
try {
ReferenceQueue refQueue = getQueue();
PhantomReference ref = new PhantomReference(this , refQueue);
ref.enqueue();
}
finally {
super .finalize();
}
}

private ReferenceQueue getQueue() {
return _queue;
}

private transient ReferenceQueue _queue;
解決方案
使用明確呼叫的清理方法,代替 finalize() 方法。
public void free() {
ReferenceQueue refQueue = getQueue();
PhantomReference ref = new PhantomReference(this , refQueue);
ref.enqueue();
}

private ReferenceQueue getQueue() {
return _queue;
}

private transient ReferenceQueue _queue;