[Java] How to Make Asynchronous Method

 

I have a long-running method which I want to run asynchronously. I transform the method into asynchronous method by running it on separate thread.

Original Code:

    public void mainMethod() throws InterruptedException{
        System.out.println("Main Method start");
        longRunningMethod("testing", new Object());
        otherMethod();
    }
   
    public Integer longRunningMethod(String param1,Object parm2) throws InterruptedException{
        System.out.println("Long running method");
        Thread.sleep(5000);
        //long process
        return 1;
    }
   
    public void otherMethod(){
        System.out.println("Other Method");
    }  
    

New Code:

public void mainMethod() throws InterruptedException{
        System.out.println("Main Method start");
        //longRunningMethod("testing", new Object());
        asyncServiceMethod("testing",new Object());
        otherMethod();
    }
   
    public Integer longRunningMethod(String param1,Object parm2) throws InterruptedException{
        System.out.println("Long running method");
        Thread.sleep(5000);
        //long process
        return 1;
    }
   
    public void otherMethod(){
        System.out.println("Other Method");
    }
   
   
    public void asyncServiceMethod(final String parm1,final Object obj){
        Runnable task = new Runnable() {

            @Override
            public void run() {
                try {
                   longRunningMethod(parm1,obj);
                } catch (Exception ex) {
                    //handle error which cannot be thrown back
                }
            }
        };
        new Thread(task, "ServiceThread").start();
    }

There are few things to consider wrapping a method into asynchronous call.

• Passing Parameters must be final
• Exception from the long-running process cannot be thrown back to mainMethod (main thread). It has to be handled at separate thread (ServiceThread in the sample)
• Returning value cannot be retrieved (Integer value in this sample) from the main Method. (If one wants to retrieve, FutureTask should be used.)

Other to read

• http://en.wikipedia.org/wiki/Asynchronous_method_invocation