When to call wait() on super

Question

When to invoke super.wait(), something like below -

synchronized (this)
      {
        while (true)
        {
          try
          {
            super.wait();
          }
          catch (InterruptedException e)
          {
            return;
          }

        }
 }

Before we answer you need to say atleast, What are you trying to achieve? — Ravi Dhoriya ツ, May 08 '14 at 12:44
well, that's a weird construct and most likely a bug. but it's still valid. why all the down votes? — Yuri, May 08 '14 at 13:16
Well, I saw this in one of the answers by @bdonlan in this post [link](http://stackoverflow.com/questions/6114320/java-monitors-how-to-know-if-waitlong-timeout-ended-by-timeout-or-by-notify). And this is the first time I saw wait being invoked on super. So asked this question out of curiosity. — user3172924, May 08 '14 at 13:45

score 2 · Accepted Answer · edited May 08 '14 at 13:10

2

Object.wait() is declared final and cannot be overridden. So super.wait() always means just wait() but is a bit longer.

edited May 08 '14 at 13:10

Hovercraft Full Of Eels

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answered May 08 '14 at 12:49

Yuri

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There is no attempt at override in the original poster's code. – Hovercraft Full Of Eels May 08 '14 at 12:51
I'm saying that in this situation wait and super.wait are equivalent because wait() is always in a superclass. – Yuri May 08 '14 at 13:04
What do you mean by "...but is a bit longer"? – Hovercraft Full Of Eels May 08 '14 at 13:10

score 1 · Answer 2 · edited May 08 '14 at 13:10

1

wait() must be called on the same object on which it it synchronized otherwise it will result in java.lang.IllegalMonitorStateException

It should be this.wait()

edited May 08 '14 at 13:10

Hovercraft Full Of Eels

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answered May 08 '14 at 12:50

Braj

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"this" and "super" both always refer to the same object. The difference between this.foo() and super.foo() only matters when the a foo() method is defined in both the object's class and in the class of one of the class's ancestors. Then "super" allows a call to the ancestor's version of the function. The normal use case is when you define this.foo() as a wrapper around the inherited function. – Solomon Slow May 08 '14 at 18:19

When to call wait() on super

2 Answers2