CODEWITHSUNDEEP
java
zzazzles
zzazzles

Reputation: 167

Does Lock work as a boolean semaphore on a single thread?

I need a mutex in Java that provides exclusive access both within a single thread and across threads. Doing something very simple like this:

    Lock l = new ReentrantLock();
    for (int i = 0; i < 5; i++) {
      Log.d(TAG, "Lock = " l.tryLock());
    }

surprising gives me true for every call:

Lock = true
Lock = true
Lock = true
Lock = true
Lock = true

Why is this, or did I fundamentally something wrong?

Upvotes: 0

Views: 116

Answers (1)

Kayaman
Kayaman

Reputation: 73568

As the name says it's re-entrant, meaning the owning thread can reacquire it.

This is a good thing, as otherwise you could easily create a single thread deadlock.

So no it does not act as a boolean semaphore. If you want a boolean semaphore, use new Semaphore(1);. Although if you do intend to cause a self-deadlock, make sure you have another thread that can resolve it.

Upvotes: 1

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