创建线程实例

一.创建线程 方法一:继承Thread类

//继承Thread 来创建一个线程类
class MyThread extends  Thread{
    @Override
    public void run(){
        System.out.println("run");
    }

}

public class Study {
    public static void main(String[] args) {
        MyThread myThread=new MyThread();
        myThread.run();
        myThread.start();//启动线程
    }

}

运行了一次java程序就是启动了一个进程，一个进程里至少会有一个线程。

main（）方法所包含的线程是主线程，和MyThread类创建出来的新线程，是一个并发执行的关系

class MyThread extends  Thread{
    @Override
    public void run(){
        while (true){
            System.out.println("hello thread!");
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

}

public class Study {
    public static void main(String[] args) throws InterruptedException {
        MyThread myThread=new MyThread();
        myThread.run();
        myThread.start();//启动线程
        while (true){
            System.out.println("hello main!");
           Thread.sleep(1000);
        }
    }

}

方法二：匿名内部类创建 Thread 子类对象  

class MyRunnable implements Runnable{
    @Override
    public void run(){
        while (true){
            System.out.println("hello thread!");
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

}

public class Study {
    public static void main(String[] args) throws InterruptedException {
       MyRunnable myRunnable=new MyRunnable();
       Thread thread=new Thread(myRunnable);
       thread.start();
        while (true){
            System.out.println("hello main!");
           Thread.sleep(1000);
        }
    }

}

 若想让多个线程都干一样的活适合使用Runnable()接口 

  MyRunnable myRunnable=new MyRunnable();
       Thread thread1=new Thread(myRunnable);
       Thread thread2=new Thread(myRunnable);
       thread1.start();
       thread2.start();

 方法三:匿名内部类创建 Runnable 子类对象

public class Study {
    public static void main(String[] args)  {
       Thread thread=new Thread(new Runnable() {
           @Override
           public void run() {
               System.out.println("hello thread");
            
           }
       });
       
    }
}

方法四：lambda 表达式创建 Runnable 子类对象

public class Study {
    public static void main(String[] args)  {
       Thread thread=new Thread(()-> {
           System.out.println("hello thread");
       });
        thread.start();
    }
}

 二.多线程优势

提高效率和运行速度

 例子:

public class Study {
    static long COUNT=100_0000_0000L;
    public static void main(String[] args) throws InterruptedException {
        example();
        concurrency();
          
    }
    public static void concurrency() throws InterruptedException {
        long beg=System.currentTimeMillis();
        Thread t1=new Thread(()->{
            long a=0;
            for (long i = 0; i {
            long a=0;
            for (long i = 0; i < COUNT; i++) {
                a++;
            }
        });
        t1.start();
        t2.start();
        t1.join();
        t2.join();
        long end=System.currentTimeMillis();
        System.out.println("执行的时间间隔"+(end-beg)+"ms");
    }
    public static void example(){
        long beg=System.currentTimeMillis();
        long a=0;
        for (long i = 0; i 

 

 

欢迎分享，转载请注明来源：内存溢出

原文地址: https://outofmemory.cn/web/2990394.html