Question

Sometimes I face I must write a piece of code like this (usually it have more nested if and more complex structure but for the example is enought)

public void printIt(Object1 a){
  if (a!=null){
     SubObject b= a.getB();
     if (b!=null){
         SubObject2 c=b.getC();
         if(c!=null){
             c.print();
         }
     }
  }
}

when I dont need to know what failed and if something is null do nothing, an approach could be

public void printIt(Object1 a){
    try{
      a.getB().getC().print();
    }catch (NullPointerException e) {
    }
}

Is there something wrong in this second form like performance or other kind of issues?

Answer 1

The exception version (similar to chains using Groovy’s safe-navigation operator ?.) makes it really easy to take the Law of Demeter (or as I call it, Demeter’s Strongly-Worded Suggestion) and make it your plaything for the night.

Similarly, deeply-nested if-statements leads to difficult-to-read code, and underneath it all, the same “violation” exists, and the cyclomatic complexity of such methods is high.

public void printIt(Object1 a) {
    if (null == a) {
        return;
    }

    SubObject b = a.getB();
    if (null == b) {
        return;
    }

    SubObject2 c = b.getC();
    if (null == c) {
        return;
    }

    c.print();
}

I’d rather see LAMs (Little Auxiliary Methods) in appropriate places that encapsulate the checks and pretty much eliminate the need for the question altogether.