Question

public void stop(){
    setRun(false);
    inComingWorkThread.interrupt();
    outGoingWorkThread.interrupt();
}

I was trying to stop those thread using interrupt call. And I got an interrupt exception.

public class OutgoingListWorker implements Runnable{

@Override
public void run() {
     while(mRunning){
          WorkOrder workOrder = getWorkOrder();
          //do something
     }
}

public synchronized WorkOrder getWorkOrder(){
    while(mWorkOrderList.size() == 0){
        try {
            this.wait();
        } catch (InterruptedException e) {e.printStackTrace();}
    }
    return mWorkOrderList.poll();
}

public synchronized void addWorkOrder(WorkOrder workOrder){
    this.notify();
    mWorkOrderList.add(workOrder);
}

The problem is getWokrOrder calls wait and if an interrupt happened this time then it won’t kill the thread.. How do I kill the blocked thread safely? Thanks in advance..

Answer 1

I think it’s because you catch the InterruptedException and continue looping…

Exception Handling

There are two ways you could deal with this:

Catch the InterruptedException outside of the loop and return null.

public synchronized WorkOrder getWorkOrder() {
    WorkOrder workOrder = null;

    try {
        while(mWorkOrderList.size() == 0) {
            this.wait();
        }

        mworkOrder = WorkOrderList.poll();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }


    return workOrder;
}

Using this option, you would need to handle the case where getWorkOrder() returns null in your run() method:

if (workOrder != null) {
    //do something
}

Or secondly, you could just throw InterruptedException and force your run() method to do something about it.

public synchronized WorkOrder getWorkOrder() throws InterruptedException {
    while(mWorkOrderList.size() == 0){
        this.wait();
    }

    return WorkOrderList.poll();
}

Interrupts

As a side note, there is no need to maintain a mRunning variable. That is exactly what interrupts do for you!

Instead of:

while(mRunning) {
    WorkOrder workOrder = getWorkOrder();
    //do something
}

Just write:

while(!Thread.interrupted()) {
    WorkOrder workOrder = getWorkOrder();
    //do something
}

And then you don’t even need to call setRun(false); at all! Here is a good tutorial about interrupts: http://download.oracle.com/javase/tutorial/essential/concurrency/interrupt.html