Question

java中通过继承Thread创建线程，程序为什么不能同时进行？结果如下

[code=java]
public class Runner
{
public static void main(String[] args)
{
runner r = new runner();
r.start();
for (int i = 0; i < 50; ++i)
System.out.println(i);
}
}
class runner extends Thread
{
public void run()
{
for (int i = 0; i < 50; ++i)
System.out.println("thread"+i);
}

}
[/code]

结果：
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
thread0
thread1
thread2
thread3
thread4
thread5
thread6
thread7
thread8
thread9
thread10
thread11
thread12
thread13
thread14
thread15
thread16
thread17
thread18
thread19
thread20
thread21
thread22
thread23
thread24
thread25
thread26
thread27
thread28
thread29
thread30
thread31
thread32
thread33
thread34
thread35
thread36
thread37
thread38
thread39
thread40
thread41
thread42
thread43
thread44
thread45
thread46
thread47
thread48
thread49

Answer 1

你这里当然不能同步执行，其实这里是两个线程你没理解吗？你自定义一个，这里的main函数也是一个线程，你自定义的线程会在你的main函数执行之后才能被唤醒 ，这种情况无法做到同步的，只能是两个system写在同一个for里面

Answer 2

你的代码没错，只是效果不明显。
输出几十个字符串，能用几毫秒。。

你把50改成5000，效果就出来了。

Answer 3

请设置同步线程安全