Java开发网 - 各位大侠：异常处理时，变量有什么特殊要求嘛？小弟在线等答案，谢了！

Topic: 各位大侠：异常处理时，变量有什么特殊要求嘛？小弟在线等答案，谢了！

1.各位大侠：异常处理时，变量有什么特殊要求嘛？小弟在线等答案，谢了！

Posted by: babyone
Posted on: 2004-09-10 20:11

//==============================================
// 程序名称：Zero.java
// 程序目的：判断一个浮点数是否等于0
//==============================================
import java.io.*;

public class Zero1{
  public static void main(String args[]){
    try
    {
      float x=Float.parseFloat(args[0]);
    }
    catch(NumberFormatException ne)
    {

      System.err.println("您必须输入一个浮点数");
    }
    catch(RuntimeException re)
    {
      System.err.println("RuntimeException:"+re);
    }
    finally
    {
    if(x==0f)
      System.out.println("浮点数x="+x+"等于0");
    else
      System.out.println("浮点数x="+x+"不等于0");
   }
  }
}

出现以下错误，请教时什么原因！　
　　---------------- JDK Debug Build ------------------
Compiling C:\Documents and Settings\user\My Documents\Modelworks\MyProjects\Zero1.java
Command line: "C:\j2sdk1.4.1\bin\javac.exe" -deprecation -g -classpath C:\DOCUME~1\user\MYDOCU~1\MODELW~1\MYPROJ~1 "C:\Documents and Settings\user\My Documents\Modelworks\MyProjects\Zero1.java"
The current directory is: C:\Documents and Settings\user\My Documents\Modelworks\MyProjects
C:\Documents and Settings\user\My Documents\Modelworks\MyProjects\Zero1.java:25: cannot resolve symbol
symbol : variable x
location: class Zero1
    if(x==0f)
^
C:\Documents and Settings\user\My Documents\Modelworks\MyProjects\Zero1.java:26: cannot resolve symbol
symbol : variable x
location: class Zero1
      System.out.println("浮点数x="+x+"等于0");
^
C:\Documents and Settings\user\My Documents\Modelworks\MyProjects\Zero1.java:28: cannot resolve symbol
symbol : variable x
location: class Zero1
      System.out.println("浮点数x="+x+"不等于0");
^
3 errors
Finished
  怎么显示都是变量x的原因啊？苦苦思索，没有答案，请教了！

2.Re:各位大侠：异常处理时，变量有什么特殊要求嘛？小弟在线等答案，谢了！ [Re: babyone]	Copy to clipboard
Posted by: why Posted on: 2004-09-10 21:29 Please use your original post for this follow-up question. Thanks. The declaration of x is in this try block, and so will be its scope try { float x=Float.parseFloat(args[0]); } .... should be float x; try { x=Float.parseFloat(args[0]); }

3.Re:各位大侠：异常处理时，变量有什么特殊要求嘛？小弟在线等答案，谢了！ [Re: babyone]	Copy to clipboard
Posted by: babyone Posted on: 2004-09-10 22:42 谢谢，在您的帮助下，终于克服了难关了！

Topic: 各位大侠 ：异常处理时，变量有什么特殊要求嘛 ？小弟在线等答案，谢了！

Topic: 各位大侠：异常处理时，变量有什么特殊要求嘛？小弟在线等答案，谢了！