如何在Java中同时调用方法？

Question

我需要为自己所在的类编写Java程序，但我需要能够一次执行6个方法。 我不知道该怎么做，但这只是我的一小部分：

public static void main(String[] args) {
    method1();
    method2();
    method3();
    method4();
    method5();
    method6();
}

这只是一次播放一种方法，而我一次需要它们。

Answer 1

使用多个线程，但是如果要从多个线程编辑相同的对象，则应该阅读并发性知识。

public static void main(String[] args) {
    new Thread() { 
        public void run() {
            method1();
        }
    }.start();
    new Thread() { 
        public void run() {
            method2();
        }
    }.start();
    //etc

    //or, as kingdamian42 pointed out, if you use java8, use this
    new Thread(() -> method1()).start();
    new Thread(() -> method2()).start();
}

Answer 2

正如@ kevin-cruijssen所说，您可以使用类似以下的内容：

public static void main(String[] args) {
    Arrays.asList(new Thread(() -> method1()), new Thread(() -> method2()))
        .parallelStream().forEach(x -> x.start());
}

但是您不能保证执行顺序。

Answer 3

如果您的计算机具有6个CPU，则可以获取有关如何执行此操作的完整示例。

    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;

    public class demo {
    private int count1 = 0;
    private int count2 = 0;
    private int count3 = 0;
    private int count4 = 0;
    private int count5 = 0;
    private int count6 = 0;

    int countA() {
        for (int i = 0; i < 1000; i++) {
            count1++;
        }
        System.out.println(count1);
        return count1;
    }

    int countB() {
        for (int i = 0; i < 1000; i++) {
            count2++;
        }
        System.out.println(count2);
        return count2;
    }

    int countC() {
        for (int i = 0; i < 1000; i++) {
            count3++;
        }
        System.out.println(count3);
        return count3;
    }

    int countD() {
        for (int i = 0; i < 1000; i++) {
            count4++;
        }
        System.out.println(count4);
        return count4;
    }

    int countE() {
        for (int i = 0; i < 1000; i++) {
            count5++;
        }
        System.out.println(count5);
        return count5;
    }

    int countF() {
        for (int i = 0; i < 1000; i++) {
            count6++;
        }
        System.out.println(count6);
        return count6;
    }

    public void execute() {
        ExecutorService executorService = Executors.newFixedThreadPool(6);

        // method reference introduced in Java 8
        executorService.submit(this::countA);
        executorService.submit(this::countB);
        executorService.submit(this::countC);
        executorService.submit(this::countD);
        executorService.submit(this::countE);
        executorService.submit(this::countF);

        // close executorService
        executorService.shutdown();
    }

    public static void main(String[] args) {
        new demo().execute();
    }

}