Is it bad practice to have my getter method change the stored value?

Question

Is it bad practice to change my getter method like version 2 in my class.

Version 1:

 public String getMyValue(){
     return this.myValue
 }
         


        

Answer 1

This actually highly depends on the contract you want to enforce with your get()-method. According to design-by-contract conventions the caller has to make sure that the preconditions are met (which means doing a validation in a setter method often is actually bad design) and the callee (I do not know if that's the correct english term for that, i.e., the called one) makes sure that the post conditions are met.

If you define your contract so that the get()-method is not allowed to change the object then you are breaking your own contract. Think about implementing a method like

public isValid() {
    return (this.myvalue == null || this.myvalue.isEmpty());
}

Advantage of this approach is that you do not have to check wether the return of your get() is "N/A" or something else. This also can be called before calling set() to validate that you do not insert illegal values into your object.

If you want to set a default value you should do that during initialization.