在主线程中创建了一个线程，该线程休眠50ms然后给变量i赋值。主线程要等该子线程结束后获得并输出i的值，使程序的输出结果如下： ​ j=10 ,a.i=10 ​ ‎ ​ ‎ ​ ‎public class Java_2 { ​ ‎ public static void main (String args[]) { ​ ‎ try { ​ ‎ Sleep a = new Sleep (); ​ ‎ Thread t = new Thread (a); ​ ‎ //*********Found********** ​ ‎ t._____________(); ​ ‎ t.join(); ​ ‎ int j= a.i; ​ ‎ System.out.println("j="+j+",a.i="+a.i); ​ ‎ } catch (Exception e) {} ​ ‎ } ​ ‎} ​ ‎ ​ ‎//*********Found********** ​ ‎class Sleep implements _________________{ ​ ‎ int i; ​ ‎ public void run () { ​ ‎ try { ​ ‎ //*********Found********** ​ ‎ Thread._______________(50); ​ ‎ i= 10; ​ ‎ } catch(InterruptedException e) {} ​ ‎ } ​ ‎}

public class Java_2 {
public static void main (String args[]) {
try {
Sleep a = new Sleep ();
Thread t = new Thread (a);
t.start();
t.join();
int j= a.i;
System.out.println("j="+j+",a.i="+a.i);
} catch (Exception e) {}
}
}

class Sleep implements Runnable{
int i;
public void run () {
try {
Thread.sleep(50); //线程休眠50ms
i= 10;
} catch(InterruptedException e) {}
}
}