We usually put unnecessary checks in our business logic to avoid failures.

Eg.

1. public ObjectABC funcABC(){

      ObjectABC obj = new ObjectABC;
     ..........
     ..........
     //its never set to null here.
     ..........
     return obj; 
} 

ObjectABC o = funABC();

if(o!=null){
//do something
}

Why do we need this null check if we are sure that it will never be null? Is it a good practice or not?

2. int pplReached = funA(..,..,..);
   int totalPpl   = funB(..,..,..);

   funA() just puts a few more restriction over result of funB().


    Double percentage = (totalPpl==0||totalPpl<pplReached) ? 0.0 : pplReached/totalPpl;

Do we again need this check?

The questions is: Aren't we swallowing some fundamental issue by putting such checks? Issues which should be shown ideally, are avoided by putting these checks.

What is the recommended way?