java多线程之Thread VS Runnable

0.线程的生命周期

1.java实现多线程方式一：

2.java实现多线程方式二：

3.两种方式的比较：

package ThreadCompare;

public class MyThreadByRunnable implements Runnable {

    private int ticket = 5;

    @Override
    public void run() {
        while(ticket>0) {
            ticket--;
            System.out.println(
                    MyThreadByThread.currentThread().getName()+"卖了1张票，还剩"+ticket+"张");

        }
    }
}

package ThreadCompare;

public class MyThreadByThread extends Thread {
    private int ticket = 5;

    @Override
    public void run() {
        while(ticket>0) {
            ticket--;
            System.out.println(
                    MyThreadByThread.currentThread().getName()+"卖了1张票，还剩"+ticket+"张");

        }
    }
}

package ThreadCompare;

import java.util.Scanner;

public class MainTest {

    public void testThread() {
        MyThreadByThread mt1 = new MyThreadByThread();
        MyThreadByThread mt2 = new MyThreadByThread();
        MyThreadByThread mt3 = new MyThreadByThread();

        mt1.start();
        mt2.start();
        mt3.start();
    }

    public void testRunnable() {
        MyThreadByRunnable mt = new MyThreadByRunnable();
        Thread t1 = new Thread(mt,"窗口1");
        Thread t2 = new Thread(mt,"窗口2");
        Thread t3 = new Thread(mt,"窗口3");

        t1.start();
        t2.start();
        t3.start();
    }


    public void demonThreadTest() {

        System.out.println("*********主线程开始执行了*********");


        DemonThread dt = new DemonThread();
        Thread t = new Thread(dt,"demon");
        t.setDaemon(true);
        t.start();

        Scanner sc = new Scanner(System.in);
        sc.next();

        System.out.println("*********主线程执行结束了*********");

    }

    public static void main(String[] args) {
        //new MainTest().testThread();
        //new MainTest().testRunnable();
        new MainTest().demonThreadTest();
    }
}

执行new MainTest().testRunnable()结果

执行new MainTest().testThread()结果

所以：

Runnable方式可以避免java单继承带来的缺陷，想实现就直接实现接口即可
Runnable实现的线程都是可以由该接口来进行连接，适用于多个线程处理同一个Runnable对象的情况

4.守护线程

Runnable实现方式设置守护线程
通过setDemon（true）方法实现（代码如上所示）。

package ThreadCompare;

public class DemonThread implements Runnable {

    private int count = 0;

    @Override
    public void run() {

        System.out.println("*********守护线程开始执行了*********");
        while (count<100) {
            count++;
            System.out.println("线程执行了 "+count+" 次");
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        System.out.println("*********守护线程执行结束了*********");
    }
}

守护线程：

5.线程同步—synchronized用法

分析：

给方法加synchronized 会使得整个方法都是在锁保护（或者叫同步控制）之内，当方法较为冗长时开销较大
只给特定代码块添加synchronized效率高