How to check if an object property exists in java?

Question

I'm trying to learn chain of responsibility pattern in Java, In below code if the successor does not exist, it gives a NullPointerException. I want to check if the successor exists like this

if(this.sucessor exists) {
  this.successor.check(Home) 
}

How can I do this?

public void next(HomeStatus Home){
   this.successor.check(Home);
}

you also can wrap the successor into an optional on java8+ - so checking that he is instanciated would be `successor.isPresent()` - good thing about it - it´s null-safe and you can also call `orDefault()` so it will return a default value (or new object) if there would be null. — LenglBoy, Mar 22 '18 at 06:38

score 3 · Answer 1 · answered Mar 22 '18 at 06:36

3

Isn't it obvious ?

public void next(HomeStatus Home){
      if(this.successor != null){
          this.successor.check(Home);
     }
}

answered Mar 22 '18 at 06:36

Emre Acar

920
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How to check if an object property exists in java?

1 Answers1