Question

    import java.util.concurrent.locks.ReentrantLock;

class Displayx
{
    public void wish(String name)
    {
        ReentrantLock lock = new ReentrantLock();
        //using locks
        lock.lock();
            for (int i = 0; i < 10; i++) 
            {
                System.out.print("Good Morning : ");
                try {
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    System.out.println("I got intruppted");
                }
                System.out.println(name);
            } 
        lock.unlock();
    }
}
class MyThreadex2 extends Thread
{
    Displayx d;
    String name;
    public MyThreadex2(Displayx d, String name) 
    {
        this.d = d;
        this.name = name;
    }
    @Override
    public void run() 
    {
        d.wish(name);
    }
}
public class ReentrantLockDemo1 {

    public static void main(String[] args) 
    {
        Displayx d = new Displayx();
        MyThreadex2 mt1 = new MyThreadex2(d, "SHOAIB");
        MyThreadex2 mt2 = new MyThreadex2(d, "RAHUL");

        mt1.start();
        mt2.start();

    }

}

我得到的输出是

Good Morning : Good Morning : SHOAIB
Good Morning : RAHUL
Good Morning : RAHUL
Good Morning : SHOAIB
Good Morning : SHOAIB
Good Morning : RAHUL
Good Morning : RAHUL
Good Morning : SHOAIB
Good Morning : SHOAIB
Good Morning : RAHUL
Good Morning : SHOAIB
Good Morning : RAHUL
Good Morning : SHOAIB
Good Morning : RAHUL
Good Morning : RAHUL
Good Morning : SHOAIB
Good Morning : SHOAIB
Good Morning : RAHUL
Good Morning : RAHUL
SHOAIB

Answer 1

将ReentrantLock lock = new ReentrantLock();移出您的方法之外。

ReentrantLock lock = new ReentrantLock();
         public void  wish(String name)
         {
             //using locks
             lock.lock();
             try {
                 for (int i = 0; i < 10; i++) {
                     System.out.print("Good Morning : ");
                     try {
                         Thread.sleep(2000);
                     } catch (InterruptedException e) {
                         System.out.println("I got intruppted");
                     }
                     System.out.println(name);
                 } 
             } finally {
                 lock.unlock();
             }

         }

Answer 2

在Java中，在方法内创建的变量可以在同一个线程中访问（作用域）。

在ReentrantLock（）方法中创建wish对象时，它对每个线程都是本地的。即您实际上是在创建个人lock每个线程的对象，因为多个线程正在进入您的关键部分代码（在try块内）。

class Displayx
{
    ReentrantLock lock = new ReentrantLock();//Use the same lock object

    public void wish(String name)
    {
        //using locks
        lock.lock();
        try {
            for (int i = 0; i < 10; i++) {
                System.out.print("Good Morning : ");
                try {
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    System.out.println("I got intruppted");
                }
                System.out.println(name);
            } 
        } finally {
            lock.unlock();
        }
    }
}

另外，正如Boris在评论中提到的那样，请确保使用Runnable或Callable接口而不是直接扩展Thread类来“编码接口”。

而不是使用synchronized关键字我使用锁概念，但我没有得到输出，因为我进入同步关键字？

2 个答案: