Avoid if for chained objects

Question

I have one complex object just like this;

Object A
   Object B
    Object C
      Object D
        property A
        property B

So If I need to show the property A in my view, I need to

  A.getB().getC().getD().getPropertyA();

but what if my user doesn`t send the object C?

so I need to create one If for every object

if(A.getB() != null){
  if(A.getB().getC() != null){
    if(A.getB().getC().getD() != null){
      //here I can show the propertyA
    }
  } 
}

now I have to show this property in 3 views

There is a better way to does this? a framework or something like this to solve this problem?

Does this answer your question? [Avoiding != null statements](https://stackoverflow.com/questions/271526/avoiding-null-statements) — OH GOD SPIDERS, Feb 26 '20 at 17:13

Andronicus · Accepted Answer · 2020-02-26T17:25:27.983

3

You can use Optional.ofNullable and map:

Optional.ofNullable(A.GetB())
    .map(B::getC)
    .map(C::getD)
    .map(D::getPropertyA)
    .orElseThrow()

P.S.1: Some developers (and linters) find this approach a code smell, but I think it's more readable that way.

P.S.2: You can use a default value with .orElse instead of .orElseThrow.

edited Feb 26 '20 at 17:25

answered Feb 26 '20 at 17:14

Andronicus

I think this is actually one case where it works pretty well, I just don't like when people pass a default value and do this when they have a local variable already. and can just use a ternary expression – Slackow Feb 26 '20 at 17:24
This approach solve all the levels of my problem? if I have null in my getD or getC? tks – Fabio Ebner Feb 26 '20 at 18:29
@FabioEbner correct. Consider upvoting / marking as correct if it helped. – Andronicus Feb 26 '20 at 18:38
Only one more doubt, and if I have one of this subobjects are a List? sample List< ObjectC> – Fabio Ebner Feb 26 '20 at 18:41
@FabioEbner then what? – Andronicus Feb 26 '20 at 18:42

1 Answers1