Question

I am testing a simple producer/ consumer example in android this is what i’m doing.

I have two EditText boxes, one being a producer and the other a consumer. The app also has a single button once this button is pressed two timers start and the producer produces while the consumer consumes. Here is my code:

   submit.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {
  Timer producerTimer = new Timer();
  producerTimer .schedule(new TimerTask(){
    @Override
    public void run(){
    producer();
  }
  },100, 300);

  Timer consumerTimer = new Timer();
  consumerTimer .schedule(new TimerTask(){
    @Override
    public void run(){
    consumer();
  }
  },100, 300);
}
});

}

Now for the other methods:

public void producer(){
    this.runOnUiThread(producer_Tick);
}

public void consumer(){
    this.runOnUiThread(consumer_Tick2);
}

private Runnable producer_Tick = new Runnable(){
    public void run(){
        put(i++);

    }
};

private Runnable consumer_Tick= new Runnable(){
    public void run(){
        int result = get();
        consumerBox.append(Integer.toString(result) + "\n");

    }
};

Here are my Synchronized methods:

public synchronized void put(int val){
    if (!empty){
        try{
            wait();
        }catch (InterruptedException e) {Log.d(TAG,"Error Putting");}
    }

    producerBox.append(Integer.toString(val) + "\n");
    empty = false;
    buffer=val;
    notify();
}

public synchronized int get(){
    if (empty){
        try{
            wait();
        }catch (InterruptedException e) {Log.d(TAG,"Error getting");}
    }

    empty = true;
    notify();
    return buffer;

}

This program runs to random points all the time. Sometimes for a couple of minuites it runs fine where consumer reads from producer etc.. However, everytime, at some point, the program will just freeze at producer and consumer at a certain value (random each time). Does anyone see a problem with the above code?

Answer 1

You should use a blocking queue to communicate between producer-consumer threads in more efficient and easy to understand way.