Java: set timeout on a certain block of code?

Question

Is it possible to force Java to throw an Exception after some block of code runs longer than acceptable?

Answer 1

I can suggest two options.

1. Within the method, assuming it is looping and not waiting for an external event, add a local field and test the time each time around the loop.

   void method() {
       long endTimeMillis = System.currentTimeMillis() + 10000;
       while (true) {
           // method logic
           if (System.currentTimeMillis() > endTimeMillis) {
               // do some clean-up
               return;
           }
       }
   }
   

2. Run the method in a thread, and have the caller count to 10 seconds.

   Thread thread = new Thread(new Runnable() {
           @Override
           public void run() {
               method();
           }
   });
   thread.start();
   long endTimeMillis = System.currentTimeMillis() + 10000;
   while (thread.isAlive()) {
       if (System.currentTimeMillis() > endTimeMillis) {
           // set an error flag
           break;
       }
       try {
           Thread.sleep(500);
       }
       catch (InterruptedException t) {}
   }
   

The drawback to this approach is that method() cannot return a value directly, it must update an instance field to return its value.