java创建线程的3种方式

Java 提供了三种创建线程的方法：

• 通过实现 Runnable 接口；
• 通过继承 Thread 类本身；
• 通过 Callable 和 Future 创建线程

通过实现 Runnable 接口

package com.demo.thread.Runnable;

public class RunnableDemo implements Runnable {
	private Thread t;
	private String threadName;// 线程名字

	RunnableDemo(String name) {
		threadName = name;
		System.out.println("Creating: " + threadName);
	}

	@Override
	public void run() {
		// TODO Auto-generated method stub
		System.out.println("Running: " + threadName);
		try {
			for (int i = 4; i > 0; i--) {
				System.out.println("Thread: " + threadName + ", " + i);
				// 让线程睡眠一会
				Thread.sleep(500);
			}
		} catch (InterruptedException e) {
			System.out.println("Thread: " + threadName + " interrupted.");
		}
		System.out.println("Thread: " + threadName + " exiting.");
	}

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

}

package com.demo.thread.Runnable;

public class TestRunnable {

	
	public static void main(String[] args) {
		
		 RunnableDemo R1 = new RunnableDemo( "Thread-1");
	      R1.start();
	      
	      RunnableDemo R2 = new RunnableDemo( "Thread-2");
	      R2.start();
		
	}


}

运行结果：

通过继承 Thread 类本身

package com.demo.thread.Thread;

public class ThreadDemo extends Thread {
	private Thread t;
	private String threadName;

	ThreadDemo(String name) {
		threadName = name;
		System.out.println("Creating " + threadName);
	}

	public void run() {
		System.out.println("Running " + threadName);
		try {
			for (int i = 4; i > 0; i--) {
				System.out.println("Thread: " + threadName + ", " + i);
				// 让线程睡眠一会
				Thread.sleep(50);
			}
		} catch (InterruptedException e) {
			System.out.println("Thread " + threadName + " interrupted.");
		}
		System.out.println("Thread " + threadName + " exiting.");
	}

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

package com.demo.thread.Thread;

public class TestThread {

	public static void main(String[] args) {
		ThreadDemo T1 = new ThreadDemo("Thread-1");
		T1.start();

		ThreadDemo T2 = new ThreadDemo("Thread-2");
		T2.start();
	}


}

运行结果：

通过 Callable 和 Future 创建线程

package com.demo.thread.Callable_Future;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;

public class CallableThreadTest implements Callable<Integer> {
    public static void main(String[] args)  
    {  
        CallableThreadTest ctt = new CallableThreadTest();  
        FutureTask<Integer> ft = new FutureTask<>(ctt);  
        for(int i = 0;i < 100;i++)  
        {  
            //System.out.println(Thread.currentThread().getName()+" 的循环变量i的值"+i);  
            if(i==20)  
            {  
                new Thread(ft,"有返回值的线程").start();  
            }  
            System.out.println(Thread.currentThread().getName()+" 的循环变量i的值"+i); 
        }  
        try  
        {  
            System.out.println("子线程的返回值："+ft.get());  
        } catch (InterruptedException e)  
        {  
            e.printStackTrace();  
        } catch (ExecutionException e)  
        {  
            e.printStackTrace();  
        }  
  
    }
    @Override  
    public Integer call() throws Exception  
    {  
        int i = 0;  
        for(;i<5;i++)  
        {  
            System.out.println(Thread.currentThread().getName()+" call()方法 ："+i);  
        }  
        return i;  
    }  
}

运行结果：