CODEWITHSUNDEEP
javasynchronizedtry-finally
Muhammad Gelbana
Muhammad Gelbana

Reputation: 4010

Behavior of a synchronized method with try and finally

Assume the following method:

public synchronized void a(){
    try{
        System.out.println("a");
        return;
    }finally{
        System.out.println("a, finally");
    }
}

I understand that the finally block will still be executed even after the return statement. One can even "override" the return value ! But my question is, will the method be unlocked after the return statement or after finally ?

Upvotes: 2

Views: 4491

Answers (3)

Subhrajyoti Majumder
Subhrajyoti Majumder

Reputation: 41220

yes it is. It'll wait up to return from function which happen after executing finally block execution.

Upvotes: 0

Kumar Vivek Mitra
Kumar Vivek Mitra

Reputation: 33544

1st of all finally will execute before the return statement....

Secondly the lock will be released only when the thread has finished executing the complete method.. ie(till the end braces of this method), Moreover this lock is of the object, so not only this method, but all the synchronized method in that class are locked.

Upvotes: 1

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726809

Since return is not executed before finally block has finished, and because the entire method is synchronized, the lock is not released until after the finally block has finished.

If you need to release the lock on exception rather than on returning from the method, you can nest your synchronized block inside the try/finally block:

public void a(){
    try {
        synchronized (this) {
            System.out.println("a");
            return;
        }
    } finally{
        System.out.println("a, finally");
    }
}

Upvotes: 2

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