CODEWITHSUNDEEP
javamultithreadingwaitproducer-consumernotify
user1769712
user1769712

Reputation: 61

Method wait() and notifyAll() is not static

public synchronized  static int get() {
    while(cheia()==false){
        try{
            wait();
          }
        catch(InterruptedException e){
        }
    }

    if (fila[inicio] != 0) {
        int retornaValor = fila[inicio];
        fila[inicio] = 0;
        inicio++;
        if (inicio == size) {
            inicio = 0;
        }
        notifyAll();
        return retornaValor;
    }
    notifyAll();
    return 0;
}

Why the wait() and notifyAll() do no run in this code?

IDE says: the method wait() (or notifyAll) is not static?

Can you help me?

Upvotes: 3

Views: 11172

Answers (4)

user10339671
user10339671

Reputation: 69

synchronized static method locks on the Class object, so naturally, you can do:

[youclass].class.wait();
[youclass].class.notify();

Upvotes: 3

Kakalokia
Kakalokia

Reputation: 3191

You're calling a non-static method such as wait() or notifyAll() from a static method. You cannot do this. Change your get method to this

public synchronized int get()

Upvotes: 1

John Vint
John Vint

Reputation: 40256

It is because you are within a static method, which means the method is executing on the class instance and not the object instance. wait and notify are instance methods.

Create an object lock instead and use that to do the synchronization and signaling.

private static final Object lock = new Object();

public static int get(){
   synchronized(lock){
      lock.wait();
      lock.notify();
      ...etc
   } 
}

Upvotes: 5

David Schwartz
David Schwartz

Reputation: 182829

What do you expect it to wait for? You have to wait for some specific object to be notified and there's no object here.

Upvotes: -1

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