为什么尽管线程正在运行，但线程中变量的值仍然保持不变？

Question

我是 Java 线程概念的新手。我创建了一个由名为 timer() 的方法组成的线程，该方法减少了变量“time”的值。我不知道我在这做错了什么，代码贴在下面：

package Threading;
/**
 * Threads are used to perform tasks cocurrently 
 * In this example we used Thread Class 
 * .start() is method use to run the method
 * .sleep is used for delay and so on
 */
public class Intro_using_Thread extends Thread {
    int time;


    public Intro_using_Thread(int time) {
        this.time = time;
    }
    

    public void timer() {
        for (int i = time; i >= 0; i--) {
            time--;
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

驱动类

package Threading;

import java.util.Scanner;

/**
 * Threads are used to perform tasks cocurrently In this example we used Thread
 * Class .start() is method use to run task
 */
public class Intro_using_thread_run {
    public static void main(String[] args) {
        int choice;
        Scanner in = new Scanner(System.in);
        Intro_using_Thread timerobj = new Intro_using_Thread(200000);
        timerobj.start();
        while (timerobj.time!=0) {
            choice = in.nextInt();
            System.out.println("The time is = "+timerobj.time);
            
        }
    }
    
}

输出

The Output is in this link

我不知道为什么堆栈溢出不让我添加图片。

Answer 1

start() 方法使线程开始执行。 JVM 调用新启动线程的 run() 方法。 所以你必须将 timer() 函数重命名为 run()。

package Threading;
/**
 * Threads are used to perform tasks cocurrently 
 * In this example we used Thread Class 
 * .start() is method use to run the method
 * .sleep is used for delay and so on
 */
public class Intro_using_Thread extends Thread {
    int time;


    public Intro_using_Thread(int time) {
        this.time = time;
    }
    

    public void run() {
        for (int i = time; i >= 0; i--) {
            time--;
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

更新：编辑解释更清楚。