等到子线程完成：Java

问题描述 ： –

步骤1：从主线程的用户输入FILE_NAME.

步骤2：对该文件执行10个操作(即计数字符,计数行等),所有这10个操作必须在隔离线程中.这意味着必须有10个子线程.

步骤3：主线程等待所有这些子线程完成.

步骤4：打印结果.

我做了什么 ：-

我做了一个3线程的示例代码.我不想要你的文件操作代码.

public class ThreadTest {
    // This is object to synchronize on.
    private static final Object waitObject = ThreadTest.class;
    // Your boolean.
    private static boolean boolValue = false;

    public final Result result = new Result();

    public static void main(String[] args) {
        final ThreadTest mytest = new Threadtest();

        System.out.println("main started");

        new Thread(new Runnable() {

            public void run() {
                System.out.println("Inside thread");

                //Int initialiser
                new Thread(new Runnable() {

                    public void run() {
                        System.out.println("Setting integer value");
                        mytest.result.setIntValue(346635);
                        System.out.println("Integer value seted");
                        try {
                            Thread.sleep(1000);
                        } catch (InterruptedException e) {
                            // Todo Auto-generated catch block
                            e.printstacktrace();
                        }
                    }
                }).start();

                //String initialiser
                new Thread(new Runnable() {

                    public void run() {
                        System.out.println("Setting string value");
                        mytest.result.setStringValue("Hello hi");
                        System.out.println("String value seted");
                        try {
                            Thread.sleep(1000);
                        } catch (InterruptedException e) {
                            // Todo Auto-generated catch block
                            e.printstacktrace();
                        }
                    }
                }).start();

                //Boolean initialiser
                new Thread(new Runnable() {

                    public void run() {
                        System.out.println("Setting boolean value");
                        mytest.result.setBoolValue(true);
                        System.out.println("Boolean value seted");
                        try {
                            Thread.sleep(1000);
                        } catch (InterruptedException e) {
                            // Todo Auto-generated catch block
                            e.printstacktrace();
                        }
                    }
                }).start();

                System.out.println("Thread is finished");

                //Notify to main thread
                synchronized (ThreadTest.waitObject) {
                    ThreadTest.boolValue = true;
                    ThreadTest.waitObject.notifyAll();
                }               
            }
        }).start();

        try {
            synchronized (ThreadTest.waitObject) {
                while (!ThreadTest.boolValue) {
                    ThreadTest.waitObject.wait();
                }
            }
        } catch (InterruptedException ie) {
            ie.printstacktrace();
        }

        System.out.println("main finished");
        System.out.println("Result is : " + mytest.result.toString());
    }
}

问题： –

我上面的代码没有给出正确的答案.我怎样才能做到这一点？

替代方案：

CountDownLatch类也是一样的.但我不想使用该类.

我看了this similar solution,我只想使用Thread的方法.

解决方法

你可以做：

Thread t = new Thread() {
    public void run() {
        System.out.println("text");
        // other complex code
    }
 };
 t.start();
 t.join();

这样,您将等到线程完成,然后继续.你可以加入多个线程：

for (Thread thread : threads) {
  thread.join();
}

原文地址：https://www.jb51.cc/java/125551.html