异常从不抛出对应的try语句的正文 [英] Exception is never thrown in body of corresponding try statement

问题描述

我在Java中遇到异常处理问题，这是我的代码。当我尝试运行这一行时，我收到编译器错误： throw new MojException（Bledne dane）; 。错误是：

异常MojException从不抛出对应的try语句的正文

这是代码：

  public class Test {
 public static void （int i = 1; i< args.length; i ++）{
尝试{
 Integer.parseInt（args [i-1]）; 
} 
 catch（MojException e）{
抛出新的MojException（Bledne dane）; 
} 
 try {
 WierszTrojkataPascala a = new WierszTrojkataPascala（Integer.parseInt（args [0]））; 
 System.out.println（args [i] +：+ a.wspolczynnik（Integer.parseInt（args [i]）））; 
} 
 catch（MojException e）{
 throw new MojException（args [i] ++ e.getMessage（））; 
} 
} 
} 
} 
  

这里是MojException的代码：

  public class MojException extends Exception {
 MojException（String s）{
超级
} 
} 
  

任何人都可以帮助我吗？

解决方案

try语句中的catch-block需要捕获正好 < $ c> try {} -block 可以抛出（或超级类）。

  try {
 // do something throws ExceptionA，eg 
抛出新的ExceptionA（我是异常Alpha！）; 
} 
 catch（ExceptionA e）{
 //做某事来处理异常，例如
 System.out.println（Message：+ e.getMessage（））; 
} 
  

您要做的是这样的：

  try {
 throw new ExceptionB（I am Exception Bravo！）; 
} 
 catch（ExceptionA e）{
 System.out.println（Message：+ e.getMessage（））; 
} 
  

这将导致编译器错误，因为您的java知道您正在尝试以捕获永远不会发生的异常。因此，您将得到：异常ExceptionA从不抛出对应的try语句。

I have a problem with exception handling in Java, here's my code. I got compiler error when I try to run this line: throw new MojException("Bledne dane");. The error is:

exception MojException is never thrown in body of corresponding try statement

Here is the code:

public class Test {
  public static void main(String[] args) throws MojException {
    // TODO Auto-generated method stub

    for(int i=1;i<args.length;i++){
      try{
        Integer.parseInt(args[i-1]);
      }
      catch(MojException e){
        throw new MojException("Bledne dane");
      }
      try{
        WierszTrojkataPascala a = new WierszTrojkataPascala(Integer.parseInt(args[0]));
        System.out.println(args[i]+" : "+a.wspolczynnik(Integer.parseInt(args[i])));
      }
      catch(MojException e){
        throw new MojException(args[i]+" "+e.getMessage());
      }
    }
  }
}

And here is a code of MojException:

public class MojException extends Exception{
    MojException(String s){
        super(s);
    }
}

Can anyone help me with this?

解决方案

A catch-block in a try statement needs to catch exactly the exception that the code inside the try {}-block can throw (or a super class of that).

try {
    //do something that throws ExceptionA, e.g.
    throw new ExceptionA("I am Exception Alpha!");
}
catch(ExceptionA e) {
    //do something to handle the exception, e.g.
    System.out.println("Message: " + e.getMessage());
}

What you are trying to do is this:

try {
    throw new ExceptionB("I am Exception Bravo!");
}
catch(ExceptionA e) {
    System.out.println("Message: " + e.getMessage());
}

This will lead to an compiler error, because your java knows that you are trying to catch an exception that will NEVER EVER EVER occur. Thus you would get: exception ExceptionA is never thrown in body of corresponding try statement.

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