为什么调试在处理多线程时不能正常工作？

Question

我有关于多线程编程的基本信息，所以我努力改进这个主题和工作调试模式，但它不能正常工作。

代码示例：

public class MultiThreadsExample implements Runnable {

private Thread t;
private String threadName;

//我有创建线程的构造函数方法

public static void main(String[] args) {
    MultiThreadsExample thread1=new MultiThreadsExample("Thread-1");
    thread1.start();
    MultiThreadsExample thread2=new MultiThreadsExample("Thread-2");
    thread2.start();

}
//runnable interface override method
@Override
public void run() {
    System.out.println("Running thread name:" + threadName);
    for (int i = 0; i < 4; i++) {
        System.out.println("Working thread: " + i + " " + threadName);
        try {
            Thread.sleep(50);
        } catch (InterruptedException ex) {
            Logger.getLogger(MultiThreadsExample.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
    System.out.println("Thread " + threadName + " interrupted.");
}

public void start() {
    System.out.println("Starting " + threadName);
    if (t == null) {
        t = new Thread(this, threadName);
        t.start();
    }
}

输出：

Creating thread name:Thread-1 Starting Thread-1 Creating thread name:Thread-2 Starting Thread-2 Running thread name:Thread-1 Working thread: 0 Thread-1 Working thread: 1 Thread-1 Working thread: 2 Thread-1 Working thread: 3 Thread-1 Thread Thread-1 interrupted. Running thread name:Thread-2 Working thread: 0 Thread-2 Working thread: 1 Thread-2 Working thread: 2 Thread-2 Working thread: 3 Thread-2 Thread Thread-2 interrupted.

Answer 1

我想，从您的评论中，您希望有一个输出，如：Working thread: 0 Thread-1 Working thread: 0 Thread-2 Working thread: 1 Thread-1 Working thread: 1 Thread-2 ...，这不是线程的工作方式。您无法精确地控制线程的执行顺序。这取决于JVM，并且高度依赖于您的机器和操作系统，而且由于您正在调试，甚至可能是您的IDE。因此，正如我所能告诉您的那样，您的代码按其应有的方式工作。

顺便说一下，这是我运行代码时的输出，因此它可以在我的机器上运行：Creating thread name: Thread-1 Starting Thread-1 Creating thread name: Thread-2 Starting Thread-2 Running thread name:Thread-1 Running thread name:Thread-2 Working thread: 0 Thread-1 Working thread: 0 Thread-2 Working thread: 1 Thread-1 Working thread: 1 Thread-2 Working thread: 2 Thread-1 Working thread: 2 Thread-2 Working thread: 3 Thread-1 Working thread: 3 Thread-2 Thread Thread-1 interrupted. Thread Thread-2 interrupted.

您应该查看一些关于java并发性的教程，比如这一个。他们解释了有关线程同步的一些基本知识。