问几个java问题
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作者:bigfox (等级:4 - 马马虎虎,发帖:2214) 发表:2004-06-29 17:04:28  楼主  关注此帖
问几个java问题
What will be the output on compiling/running the following code?

public class MyThread implements Runnable
{
String myString = "Yes ";

public void run()
{
this.myString = "No ";
}

public static void main(String[] args)
{
MyThread t = new MyThread();
new Thread(t).start();

for (int i=0; i < 10; i++)
System.out.print(t.myString);
}
}

问题是,myString 不是public的,为什么main()最后一行不会报错呢? 我把main()移到另一个class中,也能run,都有点学糊涂了我 :P


第二个问题

public class Static
{
static
{
int x = 5;
}

static int x,y;
public static void main(String args[])
{
x--;
myMethod();
System.out.println(x + y + ++x);
}

public static void myMethod()
{
y = x++ + ++x;
}
}

这里有两个static, 一个是static{ int x = 5;} 另一个是static int x;
如何拿到在那个static{}中的x? 还想知道前者有什么用吗?


多谢!!
Put your OWN COOL signature here!
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作者:bigfox (等级:4 - 马马虎虎,发帖:2214) 发表:2004-06-30 15:36:01  2楼
ur mails...got a lot...how?
really? help me pass them to 阿修罗 bah 3x 3x
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作者:bigfox (等级:4 - 马马虎虎,发帖:2214) 发表:2004-06-30 16:01:17  3楼
Answers:1) Of course no error, since you are accessing t.myString inside t itself! Note that your main method is part of the MyThread class. Furthermore, Java's default access specification for member variables and methods is NOT private! The default specification allows access from any class in the same package. As your MyThread class is not in any package (effectively in the so-called "global" package), and I suppose so is your other test classes, myString is accessible. 2) The x in the first static scope cannot be accessed, because it is destroyed straightaway after it is declared! Note that static {...} structure is usually useful only in the global scope, i.e., outside any class. Basically, it provides static initialization routines to be executed before everything else (of course, there are still necessary initializations like class loading before this). Don't confuse the static code fragment with static member variable of a class.
are u saying that
any var(s) declared within static{} will not be reachable any more after the control flow gets out of that block?

pls correct me if i am wrong. 3x :D
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作者:bigfox (等级:4 - 马马虎虎,发帖:2214) 发表:2004-06-30 16:01:40  4楼
What's SCJP?Sun Certified Java Programmer? Is it an interesting cert?
not suit for u at all.
it is only for junior programmers, but it is the prerequisite cert for SCJD SCBCD etc.
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作者:bigfox (等级:4 - 马马虎虎,发帖:2214) 发表:2004-06-30 16:56:01  5楼
really? help me pass them to 阿修罗 bah 3x 3x
只要不是来自PR/UOB, 就不是很急.
如果他没空,那我就找个时间过去一趟 huhu :)

你加我msn吧, smallfox33@
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