Java – how do I pass parameters to a thread and get the return value?

public class CalculationThread implements Runnable {

public class CalculationThread implements Runnable {

    int input;
    int output;

    public CalculationThread(int input)
    {
        this.input = input;
    }

    public void run() {
        output = input + 1;
    }

    public int getResult() {
        return output;
    }
}

Other places:

Thread thread = new Thread(new CalculationThread(1));
thread.start();
int result = thread.getResult();

Of course, thread GetResult () does not work (it attempts to call this method from the thread class)

You got what I wanted How can I achieve this in Java?

Solution

This is the job of the thread pool You need to create a callable < R > which is a value returned by runnable and sent to the thread pool

The result of this operation is future < R > This is a pointer to this job. It will contain the calculated value. If the job fails, it will not

public static class CalculationJob implements Callable<Integer> {
    int input;

    public CalculationJob(int input) {
        this.input = input;
    }

    @Override
    public Integer call() throws Exception {
        return input + 1;
    }
}

public static void main(String[] args) throws InterruptedException {
    ExecutorService executorService = Executors.newFixedThreadPool(4);

    Future<Integer> result = executorService.submit(new CalculationJob(3));

    try {
        Integer integer = result.get(10,TimeUnit.MILLISECONDS);
        System.out.println("result: " + integer);
    } catch (Exception e) {
        // interrupts if there is any possible error
        result.cancel(true);
    }

    executorService.shutdown();
    executorService.awaitTermination(1,TimeUnit.SECONDS);
}

Print:

result: 4