CODEWITHSUNDEEP
javamultithreading
syam kumar c
syam kumar c

Reputation: 90

How to take the results outside the thread in java

i want to run 2 codes simultaneously in java so i used thread.here i want to get the results from both thread 1 and thread 2 .Please help Also im not getting thread.getResults i think its not working is there any way to get the results

    Thread thread1 = new Thread() {
    private Object result;

    @Override
    public void run() {
        takeInfofromDB();
        result = doSomeLongCalculationsWithThatData();
    }

    public Object getResult() {
        return result;
    }
}

Thread thread2 = new Thread() {
    private Object result;

    @Override
    public void run() {
        takeInfofromDB2();
        result = doSomeLongCalculationsWithThatData2();
    }

    public Object getResult() {
        return result;
    }
}

thread1.start();
thread2.start();
thread1.join();
thread2.join();

Object result1 = thread1.getResult();
Object result2 = thread2.getResult();

Upvotes: 2

Views: 191

Answers (3)

Lahiru Gunathilake
Lahiru Gunathilake

Reputation: 184

I would like to suggest another simple solution.

Object result1;
Object result2;

Thread thread1 = new Thread( () -> {
    takeInfofromDB();
    result1 = doSomeLongCalculationsWithThatData();
});

Thread thread2 = new Thread( () -> {
    takeInfofromDB2();
    result2 = doSomeLongCalculationsWithThatData();
});

thread1.start();
thread2.start();

thread1.join();
thread2.join();

Then you don't need additional getResult() method. You can just use result1 and result2 after calling joins.

Upvotes: 0

Nikolai Shevchenko
Nikolai Shevchenko

Reputation: 7521

thread1 and thread2 are instances of Thread class, which doesn't have getResult() method. You have to create your own non-anonymous classes that extends Thread.

public class Db1Thread extends Thread {
    private Object result;

    @Override
    public void run() {
        takeInfofromDB();
        result = doSomeLongCalculationsWithThatData();
    }

    public Object getResult() {
        return result;
    }
}

And then

Db1Thread thread1 = new Db1Thread();
thread1.start();
thread1.join();
Object result1 = thread1.getResult();

P.S. the better approach is to use CompletableFuture from Java 8+. Here is the brief guide https://www.baeldung.com/java-completablefuture

Upvotes: 0

matt
matt

Reputation: 12346

This is exactly the job for a Future.

ExecutorService service = Executors.newFixedThreadPool(2);

Future<Object> future1 = service.submit( ()->{
     takeInfofromDB();
     return doSomeLongCalculationsWithThatData();
} );

Future<Object> future2 = service.submit( ()->{
     takeInfofromDB2();
     return doSomeLongCalculationsWithThatData2();
} );
Object result1 = future1.get();
Object result2 = future2.get();

Also, on another note. With java 11 and higher you can use var.

var thread1 = new Thread() {
    private Object result;

    @Override
    public void run() {
        takeInfofromDB();
        result = doSomeLongCalculationsWithThatData();
    }

    public Object getResult() {
        return result;
    }

}

Then it retains your new methods.

thread1.start();
thread1.join();
Object result = thread1.getResult();

Upvotes: 4

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