檢視 SCJP 1.6版考題 220 的原始碼

Which factor or factors 
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<br>&nbsp; A. It is possible for more than two threads to deadlock at once. 
<br>&nbsp; B. The JVM implementation guarantees that multiple threads cannot enter into a deadlocked state. <br>&nbsp; C. Deadlocked threads release once their sleep() method's sleep duration has expired. 
<br>&nbsp; D. Deadlocking can occur only when the wait(), notify() and notifyAll() methods are used incorrectly. <br>&nbsp; E. It is possible for a single-threaded application to deadlock if synchronized blocks are used incorrectly. 
<br>&nbsp; F. If a piece of code is capable of deadlocking, you cannot eliminate the possibility of deadlocking by inserting invocations of Thread.yield(). <br> <br> 



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<span style="font-size:medium;">解答</span>

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<span style="font-size: medium;">Ans: A F   </span>

<span style="font-size:medium;"> 解說:
&nbsp;&nbsp;A 有可能2個以上的執行進入死結狀態 是的 
<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;B JVM實作保證執行緒不會進入deadlock à 死結避免是程式設計師要做的事，不是環境要做的事 
<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;F 若部份的程式碼有產生死結的可能，你無法藉由插入Thread.yield()呼叫而消除死結的可能性。 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;à 死結要避免必須程式本身要進行資源配置計劃，而不是藉由插入一個退讓(yield)敘述就可以避免的。 
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{{SCJP 1.6版考題講解}}