java synchronized內建鎖的可重入性
《java併發程式設計實踐》一書中，關於synchronized內建鎖的可重入的例子如下：
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public class Widget {
public synchronized void doSomething() {
...
}
}
public class LoggingWidget extends Widget {
public synchronized void doSomething() {
System.out.println(toString() + ": calling doSomething");
super.doSomething();//若內建鎖是不可重入的，則發生死鎖
}
}
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小弟在此次有兩點疑惑：
1、LoggingWidget 的物件呼叫doSomething方法時，鎖物件為LoggingWidget物件
super.doSomething()呼叫是鎖物件是誰？LoggingWidget物件 還是 Widget 的Class物件？
執行程式，檢視thread dump發現：呼叫super.doSomething()時鎖物件依然是LoggingWidget物件。
"執行緒#1" prio=6 tid=0x0bd60400 nid=0x16f8 waiting on condition [0x0bf8f000..0x0bf8fd68]
java.lang.Thread.State: TIMED_WAITING (sleeping)
at java.lang.Thread.sleep(Native Method)
at Widget.doSomething(Widget.java:4)
- locked <0x03fbc150> (a LoggingWidget)
at LoggingWidget.doSomething(LoggingWidget.java:5)
- locked <0x03fbc150> (a LoggingWidget)
at LoggingWidget$1.run(LoggingWidget.java:15)
Locked ownable synchronizers:
- None
2、在網上搜索發現，大夥都如是說：
