Java Null Pointer Exception, how can i fix that?

Question

I'm in trouble with that thing.

public class Money {
          String girl ;
          Money mon ;
      public void sorry (){
          mon.girl = "Isabel" ; //I want to do that (here is basic part) but...
                                //..I get Null Pointer Exception
      }
}

How can i fix that problem? I really need the solve, if you'll help me I appreciate that guys.

As you are trying to access the variable from the same class use : `girl = "Isabel";` — Sitam Jana, May 15 '14 at 09:28
yes you declared mon, but it is null unless until you initialized it that is why you are having NPE — Rick Royd Aban, May 15 '14 at 09:32
don't have an instance variable of the Class 's type within the class. that's asking for trouble. — Stultuske, May 15 '14 at 09:37

score 1 · Answer 1 · answered May 15 '14 at 09:28

reolace your code with

public class Money {
          String girl ;
          **Money mon = new Money();**
          mon.girl = "Isabel" ; //I want to do that (here is basic part) but...
                                //..I get Null Pointer Exception
     }

It was due to not initializing the object Money mon .

score 0 · Answer 2 · answered May 15 '14 at 09:27

You have to create an instance of the Money object before set any property.

Money mon = new Money();

Moreover, it seems it's to simplify, but your code looks strange :

Definition

public class Money {
   String girl ;
}

Usage

Money mon = new Money();
mon.girl = "Isabel" ;

score 0 · Answer 3 · answered May 15 '14 at 09:31

0

You must need to initialize i.e need to create a instance of object Money before use.

Try to initialize it in this way.

public class Money {
          String girl ;
          Money mon = new Money(); // created instance for Money.

          mon.girl = "Isabel" ; 
     }

answered May 15 '14 at 09:31

Java

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but this is something you really don't want to do. it'll be a recursive call to the Money constructor, crashing the application within seconds – Stultuske May 15 '14 at 09:36

Java Null Pointer Exception, how can i fix that?

3 Answers3