• run() 和 start() 的区别

    1） start：

    用start方法来启动线程，真正实现了多线程运行，这时无需等待run方法体代码执行完毕而直接继续执行下面（指主线程下面）的代码。通过调用Thread类的start()方法来启动一个线程，这时此线程处于就绪（可运行）状态，并没有运行，一旦得到cpu时间片，就开始执行run()方法，这里方法run()称为线程体，它包含了要执行的这个线程的内容，Run方法运行结束，此线程随即终止。

     1 package com.mianshi.easy;
 2 public class StartRunTest {
 3     /**
 4      * 直接调用run()和用start()启动一个线程的差别 
 5      */
 6         
 7     public static void main(String[] args){
 8         Thread thread=new ThreadDemo();
 9         //第一种
10         //表明: run()和其他方法的调用没任何不同,main方法按顺序执行了它,并打印出最后一句
11         /*thread.run();
12         for(int i=0;i<100;i++){
13             System.out.println(i);
14         }*/
15         
16         //第二种
17         //表明: start()方法重新创建了一个线程,在main方法执行结束后,由于start()方法创建的线程没有运行结束,
18         //因此主线程未能退出,直到线程thread也执行完毕.这里要注意,默认创建的线程是用户线程(非守护线程)
19         thread.start();
20         for(int i=0;i<100;i++){
21             System.out.println(i);
22         }
23         
24         //第三种
25         //1、为什么没有打印出100句呢?因为我们将thread线程设置为了daemon(守护)线程,程序中只有守护线程存在的时候,是可以退出的,所以只打印了七句便退出了
26         //2、当java虚拟机中有守护线程在运行的时候，java虚拟机会关闭。当所有常规线程运行完毕以后，
27         //守护线程不管运行到哪里，虚拟机都会退出运行。所以你的守护线程最好不要写一些会影响程序的业务逻辑。否则无法预料程序到底会出现什么问题
28         /*thread.setDaemon(true);
29         thread.start();*/
30         
31         //第四种
32         //用户线程可以被System.exit(0)强制kill掉,所以也只打印出七句
33        /* thread.start();
34         System.out.println("main thread is over");
35         System.exit(1);*/
36     }
37     
38     public static class ThreadDemo extends Thread{
39         @Override
40         public void run() {
41             for (int i = 0; i < 100; i++) {
42                 System.out.println("This is a Thread test"+i);
43             }
44         }
45     }
46 }
    View Code

    结果：

    0
1
2
3
4
5
6
7
This is a Thread test0
This is a Thread test1
This is a Thread test2
This is a Thread test3
This is a Thread test4
8
This is a Thread test5
This is a Thread test6
This is a Thread test7
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
This is a Thread test8
This is a Thread test9
This is a Thread test10
This is a Thread test11
This is a Thread test12
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
This is a Thread test13
78
This is a Thread test14
This is a Thread test15
This is a Thread test16
This is a Thread test17
This is a Thread test18
This is a Thread test19
This is a Thread test20
This is a Thread test21
This is a Thread test22
This is a Thread test23
This is a Thread test24
This is a Thread test25
This is a Thread test26
This is a Thread test27
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
This is a Thread test28
This is a Thread test29
This is a Thread test30
This is a Thread test31
This is a Thread test32
This is a Thread test33
This is a Thread test34
This is a Thread test35
This is a Thread test36
This is a Thread test37
This is a Thread test38
This is a Thread test39
This is a Thread test40
This is a Thread test41
This is a Thread test42
This is a Thread test43
This is a Thread test44
This is a Thread test45
This is a Thread test46
This is a Thread test47
This is a Thread test48
This is a Thread test49
This is a Thread test50
This is a Thread test51
This is a Thread test52
This is a Thread test53
This is a Thread test54
This is a Thread test55
This is a Thread test56
This is a Thread test57
This is a Thread test58
This is a Thread test59
This is a Thread test60
This is a Thread test61
This is a Thread test62
This is a Thread test63
This is a Thread test64
This is a Thread test65
This is a Thread test66
This is a Thread test67
This is a Thread test68
This is a Thread test69
This is a Thread test70
This is a Thread test71
This is a Thread test72
This is a Thread test73
This is a Thread test74
This is a Thread test75
This is a Thread test76
This is a Thread test77
This is a Thread test78
This is a Thread test79
This is a Thread test80
This is a Thread test81
This is a Thread test82
This is a Thread test83
This is a Thread test84
This is a Thread test85
This is a Thread test86
This is a Thread test87
This is a Thread test88
This is a Thread test89
This is a Thread test90
This is a Thread test91
This is a Thread test92
This is a Thread test93
This is a Thread test94
This is a Thread test95
This is a Thread test96
This is a Thread test97
This is a Thread test98
This is a Thread test99
    View Code

    子线程成功创建，主线程的代码也在继续运行，而且证明了子线程短暂等待CPU时间片的过程，此过程中主线程没有停止。

    2） run：

    run()方法只是类的一个普通方法而已，如果直接调用Run方法，程序中依然只有主线程这一个线程，其程序执行路径还是只有一条，还是要顺序执行，还是要等待run方法体执行完毕后才可继续执行下面的代码，这样就没有达到写线程的目的。

     1 package com.mianshi.easy;
 2 public class StartRunTest {
 3     /**
 4      * 直接调用run()和用start()启动一个线程的差别 
 5      */
 6         
 7     public static void main(String[] args){
 8         Thread thread=new ThreadDemo();
 9         //第一种
10         //表明: run()和其他方法的调用没任何不同,main方法按顺序执行了它,并打印出最后一句
11         thread.run();
12         for(int i=0;i<100;i++){
13             System.out.println(i);
14         }
15         
16         //第二种
17         //表明: start()方法重新创建了一个线程,在main方法执行结束后,由于start()方法创建的线程没有运行结束,
18         //因此主线程未能退出,直到线程thread也执行完毕.这里要注意,默认创建的线程是用户线程(非守护线程)
19         /*thread.start();
20         for(int i=0;i<100;i++){
21             System.out.println(i);
22         }*/
23         
24         //第三种
25         //1、为什么没有打印出100句呢?因为我们将thread线程设置为了daemon(守护)线程,程序中只有守护线程存在的时候,是可以退出的,所以只打印了七句便退出了
26         //2、当java虚拟机中有守护线程在运行的时候，java虚拟机会关闭。当所有常规线程运行完毕以后，
27         //守护线程不管运行到哪里，虚拟机都会退出运行。所以你的守护线程最好不要写一些会影响程序的业务逻辑。否则无法预料程序到底会出现什么问题
28         /*thread.setDaemon(true);
29         thread.start();*/
30         
31         //第四种
32         //用户线程可以被System.exit(0)强制kill掉,所以也只打印出七句
33        /* thread.start();
34         System.out.println("main thread is over");
35         System.exit(1);*/
36     }
37     
38     public static class ThreadDemo extends Thread{
39         @Override
40         public void run() {
41             for (int i = 0; i < 100; i++) {
42                 System.out.println("This is a Thread test"+i);
43             }
44         }
45     }
46 }
    View Code

    结果：

    This is a Thread test0
This is a Thread test1
This is a Thread test2
This is a Thread test3
This is a Thread test4
This is a Thread test5
This is a Thread test6
This is a Thread test7
This is a Thread test8
This is a Thread test9
This is a Thread test10
This is a Thread test11
This is a Thread test12
This is a Thread test13
This is a Thread test14
This is a Thread test15
This is a Thread test16
This is a Thread test17
This is a Thread test18
This is a Thread test19
This is a Thread test20
This is a Thread test21
This is a Thread test22
This is a Thread test23
This is a Thread test24
This is a Thread test25
This is a Thread test26
This is a Thread test27
This is a Thread test28
This is a Thread test29
This is a Thread test30
This is a Thread test31
This is a Thread test32
This is a Thread test33
This is a Thread test34
This is a Thread test35
This is a Thread test36
This is a Thread test37
This is a Thread test38
This is a Thread test39
This is a Thread test40
This is a Thread test41
This is a Thread test42
This is a Thread test43
This is a Thread test44
This is a Thread test45
This is a Thread test46
This is a Thread test47
This is a Thread test48
This is a Thread test49
This is a Thread test50
This is a Thread test51
This is a Thread test52
This is a Thread test53
This is a Thread test54
This is a Thread test55
This is a Thread test56
This is a Thread test57
This is a Thread test58
This is a Thread test59
This is a Thread test60
This is a Thread test61
This is a Thread test62
This is a Thread test63
This is a Thread test64
This is a Thread test65
This is a Thread test66
This is a Thread test67
This is a Thread test68
This is a Thread test69
This is a Thread test70
This is a Thread test71
This is a Thread test72
This is a Thread test73
This is a Thread test74
This is a Thread test75
This is a Thread test76
This is a Thread test77
This is a Thread test78
This is a Thread test79
This is a Thread test80
This is a Thread test81
This is a Thread test82
This is a Thread test83
This is a Thread test84
This is a Thread test85
This is a Thread test86
This is a Thread test87
This is a Thread test88
This is a Thread test89
This is a Thread test90
This is a Thread test91
This is a Thread test92
This is a Thread test93
This is a Thread test94
This is a Thread test95
This is a Thread test96
This is a Thread test97
This is a Thread test98
This is a Thread test99
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
    View Code

    并没有产生子线程，而是普通的方法调用，只有等调用方法执行完后，主线程才能继续执行处后面的代码。

    总结：调用start方法方可启动线程，而run方法只是thread的一个普通方法调用，还是在主线程里执行。

    参考：http://visionsky.blog.51cto.com/733317/431397
  • 相关阅读:
    使用 Hudson 进行持续集成
    hudson中的ftp插件
    Tomcat i18n 对 URL 进行 UTF8 解码
    Product deploy using NAnt and NSIS [技术点滴]
    切身体会到对微软的无语——关于VS2008的配置项
    How to create your own home SVN repository with Xampp/Apache
    CVS+VS2003+SetupFactory建设每日构建（Daily build）
    期待 JDK、Tomcat和MySQL的绿色安装方法
    FolderBrowserDialog 使用时路径问题
    无敌删除命令
  • 原文地址：https://www.cnblogs.com/gongxing/p/4654469.html
Copyright © 2020-2023  润新知