java 创建线程

java创建线程有3种方式：

(1)继承Thread
(2)实现Runnable接口
(3)实现Callable接口

1、继承Thead

package com.java.thread;

public class ThreadClient {

    public static void main(String[] args) {
        Print p1 = new Print();
        Print p2 = new Print();
        p1.start();
        p2.start();

    }

}

class Print extends Thread{
    @Override
    public void run(){
        for(int i=0;i<10;i++){
            System.out.println(Thread.currentThread().getName()+":"+i);
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

2、实现Runnable接口

package com.java.thread;

public class ThreadClient1 {

    public static void main(String[] args) {
        Runnable p1 = new Salesman("Jack");
        Runnable p2 = new Salesman("Iris");

        Thread t1 = new Thread(p1);
        Thread t2 = new Thread(p2);

        t1.start();
        t2.start();
    }

}

class Salesman implements Runnable{

    private int ticket=100;
    private String name;
    Salesman(String name){
        this.name=name;
    }

    @Override
    public void run(){
        while(ticket>0){
             System.out.println(ticket--+" is saled by "+name+","+Thread.currentThread().getName());
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
         }
    }
}

3、实现Callable接口

package com.java.thread;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class CallType {

    public static void main(String[] args) {
        ExecutorService es = Executors.newCachedThreadPool();
        List<Future<String>> results = new ArrayList<Future<String>>();
        for(int i=0;i<5;i++){
            results.add(es.submit(new TaskWithResult(i)));
        }

        for(Future<String> fs : results){
            try {
                System.out.println(fs.get());
            } catch (InterruptedException | ExecutionException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

class TaskWithResult implements Callable<String>{
    private int id;
    public TaskWithResult(int id){
        this.id = id;
    }
    @Override
    public String call() throws Exception {
        return "result of TaskWithResult" + id;
    }
}

由于Java只支持单继承，所以用继承的方式创建线程，比较死板，不够灵活；用实现接口的方式创建线程，可以实现多个接口，比较灵活。
Runnable和Callable接口的区别：
(1)Callable重写的方法是call(),Runnable重写的方法是run()。
(2)Callable的任务执行后可返回值，而Runnable不能返回值。
(3)call方法可以抛出异常，run()不可以。