Question

i was trying to run the following code but i am getting error please clarify my doubt

import java.util.*;

    class Except 
    { public class AlfaException extends Exception{}
      public static void main(String[] args)
       {

        int b;
        Scanner s=new Scanner(System.in);
          try
            { 
              b=s.nextInt();
            }
          catch(InputMismatchException ex)
               {
                 try
                     {
                        if(('b'> 67)&&('b'<83)){}
                     }
                 catch(AlfaException e){
                   throw new AlfaException("hello");
                    }         
                 System.out.println("error found");
               }
        }
    }  



 Except.java:20: non-static variable this cannot be referenced from a static cont
ext
               throw new AlfaException("hello");
                     ^

1 error

Answer 1

Static context is a context that runs on class without actual instance of that class. Your main method is static, that means it can only access static variables. However, your AlfaException is not static. Meaning that it will be bound to an instance of Except class – which you do not have.

Therefore you have 2 choises:

1. Make AlfaException also static: public static class AlfaException extends Exception{}. That will make it reside in static scope so it will be possible to access it from static functions.
2. Move all the main(...) method logic into non-static context. Create a function called doWork() that is not static, move all the code from main to doWork, and then call it like this:

.

public static void main(String[] args) {
    Except instance = new Except();
    instance.doWork();
}