How to use threads in MVC architecture?

Question

One of my implementation classes has methods that takes quite long to finish and that makes my view to freeze. So these methods must be threaded!

All these methods are returning data with HashMaps or Lists.

My controller is getting that data by calling them and then pass them to the View.

What i can't figure out is where should i create the thread. Should it be in the Controller layer or in the implementation class (and how so since i have many methods there).

Also i need to refresh the view only when the thread work is finished. These methods are going to be re-called.

I'm really lost in all those threading techniques i came across.

Controller:

SomeParser someParser = new FirstParserImpl();

HashMap<String,String> map = someParser.parseSomething();
loadTableView(map);

FirstParserImpl:

public HashMap<String,String> parseSomething() {
    //opening http connection, scrape and parse data. This takes long time!
    return map;
}

@MichaelPickett Sorry, i thought my question would be descriptive enough. Please give me some time to post some of my code. Thanks — pror21
– pror21, Commented Sep 23, 2016 at 17:07
I tried to be simple on how i'm calling these methods for the sake of your eyes. — pror21
– pror21, Commented Sep 23, 2016 at 17:35

GOXR3PLUS · Accepted Answer · 2016-09-23 21:25:32Z

Combining James_D answer + Services(tutorial) you can do the below: (Basically a Service starts a Thread which will do the work you want and return a result)

public class WorkerService extends Service<Map<String, String>> {

    /**
     * Constructor
     */
    public WorkerService () {

        // if succeeded
        setOnSucceeded(s -> {
            //code if Service succeeds
        });

        // if failed
        setOnFailed(fail -> {
            //code it Service fails
        });

        //if cancelled
        setOnCancelled(cancelled->{
            //code if Service get's cancelled
        });
    }

    /**
    * This method starts the Service
    */
    public void startTheService(){
        if(!isRunning()){
           //...
           reset();
           start();
        }

    }

    @Override
    protected Task<Map<String, String>> createTask() {
        return new Task<Map<String, String>>() {
            @Override
            protected Void call() throws Exception {

                    //create a Map<String, String>
                    Map<String,String> map  = new HashMap<>();

                   //create other variables here

                   try{
                        //some code here
                        //.....do your manipulation here

                        updateProgress(++currentProgress, totalProgress);
                    }

                } catch (Exception ex) {                  
                    return null; //something bad happened so you have to do something instead of returning null
                }

                return map;
            }
        };
    }

}

James_D · Accepted Answer · 2016-09-23 17:46:27Z

2

Use a Task. You can do this directly in the controller class:

Task<Map<String, String>> parseDataTask = new Task<Map<String, String>>() {

    @Override
    public Map<String, String> call() {
        SomeParser someParser = new FirstParserImpl();
        return someParser.parseSomething();
    }
};

parseDataTask.setOnSucceeded(e -> {
    Map<String,String> parseResults = parseDataTask.getValue();
    // update UI here with parseResults, e.g:
    loadTableView(parseResults);
});

Thread t = new Thread(parseDataTask);
t.setDaemon(true);
t.start();

answered Sep 23, 2016 at 17:46

James_D

211k16 gold badges312 silver badges345 bronze badges

Collectives™ on Stack Overflow

How to use threads in MVC architecture?

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related