CODEWITHSUNDEEP
javareturnreturn-value
Oliver Bak
Oliver Bak

Reputation: 151

I need help to return

Im in progress making my first GUI program, and run into a little problem. I need to return the String value, so i can use it in the method "saying". This part is a sub class - a class built in another class.. The error return value; gets is: void methods cant return values. I know i have to replace void, but with what?? regards Oliver

private class Eventhandler implements ActionListener{
    double amount;


    public void actionPerformed(ActionEvent event){

        String string = "";
        String string1 = "";

        if(event.getSource()==item1)
            string=String.format(event.getActionCommand());
        else if(event.getSource()==item2)
        string1=String.format(event.getActionCommand());

        JOptionPane.showMessageDialog(null, string);

        double fn = Double.parseDouble(string);
        double sn = Double.parseDouble(string1);
        double amount = fn + sn;

        String value = Double.toString(amount);

        return value;


    }

}
public void saying(){
    System.out.println(value);
}

}

Upvotes: 0

Views: 84

Answers (3)

Dodd10x
Dodd10x

Reputation: 3349

Unless you need the String value elsewhere in your program:

Replace 

public void saying(){
   System.out.println(value);
}

with 

public void saying(String value){
    System.out.println(value);
}

And then change

return value;

To

saying(value);

Upvotes: 0

Deepak
Deepak

Reputation: 2895

You can make an instance variable and can initilise it in actionPerformed method like below

private class Eventhandler implements ActionListener{
String value=''


   public void actionPerformed(ActionEvent event){
      value="newvalue";
      // rest code goes here
   }
}

you can not change the return type of api defined method

Upvotes: 0

Claudiu
Claudiu

Reputation: 229361

As others have said, you can't return anything from actionPerformed because that's specified in the ActionListener interface. Even if you could, it wouldn't do you any good, because you're not the one calling the actionPerformed function.

What you want to do is give the parent class value, somehow. One way to do this is to have value be a field on the parent class. Then you can set it from the actionPerformed function:

private class ParentClass {
    private String value;

    //... stuff ...

    private class Eventhandler implements ActionListener{
        double amount;

        public void actionPerformed(ActionEvent event){
            //... stuff ...

            ParentClass.this.value = Double.toString(amount);
        }
    }

    public void saying(){
        System.out.println(value);
    }
}

Note that you can't do this.value = value in the inner class, because this in that funcion refers to the Eventhandler instance. You have to use the ParentClass.this syntax to get the parent class's this. Replace ParentClass with the actual name of your parent class.

A better way might be to have a setValue() function on the parent class, which the inner Eventhandler class calls. It depends on what you want to do.

Upvotes: 5

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