CODEWITHSUNDEEP
java
Dicky Ho
Dicky Ho

Reputation: 244

Simplify null checkiing when using Java

In my code, I need to do something like this: System.out.println(obj1.getObj2().getObj3().getObj4()); but all objects are possible to be null, so I have to write like this:

   if (obj1 == null) {
            System.out.println("");
    }
    else if (obj1.getObj2() == null) {
        System.out.println("");
    }
    else if (obj1.getObj2().getObj3() == null) {
        System.out.println("");
    }
    else if (obj1.getObj2().getObj3().getObj4() == null) {
        System.out.println("");
    }
    else {
        System.out.println(obj1.getObj2().getObj3().getObj4());
    }

Is there anyway that I am simplify the above code? Remarks: I am using J2SE 6.0

Upvotes: 2

Views: 825

Answers (5)

Hauleth
Hauleth

Reputation: 23556

If you are in control of all that methods source code, then you can use null object that will return itself on all subsequent calls. Other option is to use something like maybe monad and then chain it by some kind of bind operation.

Upvotes: 0

Jim Garrison
Jim Garrison

Reputation: 86764

An alternative approach

Obj2Type obj2 = obj1==null ? null : obj1.getObj2();
Obj3Type obj3 = obj2==null ? null : obj2.getObj3();
Obj4Type obj4 = obj3==null ? null : obj4.getObj4();
System.out.println(obj4==null ? "" : obj4.toString()); // toString() in case obj4 is not String

Upvotes: 2

TheLostMind
TheLostMind

Reputation: 36304

Certainly not the best solution around (but this code is way cleaner than the if -else approaches :P.. * probably slower but cleaner* :

public static String getValue(SomeClass obj1) {
    String s = "";
    try {
       s =  obj1.getObj2().getObj3().getObj4().toString();
    }
    catch (NullPointerException ex) {
        // set s to something else if you want to.
    }
    return s;
}

And you can use : System.out.println(getValue(obj1));

Upvotes: 4

edge
edge

Reputation: 267

if(obj1 == null || obj1.getObj2() == null || obj1.getObj2().getObj3() == null ||  obj1.getObj2().getObj3().getObj4() == null){
System.out.println("");
}
else{
System.out.println(obj1.getObj2().getObj3().getObj4());
}

Upvotes: 2

Jörn Buitink
Jörn Buitink

Reputation: 2916

if clauses will be checked from left to right, so you can write:

if (obj1 == null || 
            obj1.getObj2() == null || 
            obj1.getObj2().getObj3() == null || 
            obj1.getObj2().getObj3().getObj4() == null) {
        System.out.println("");
} else {
    System.out.println(obj1.getObj2().getObj3().getObj4());
}

In this code, if obj1 == null, the other conditions won't be checked anymore.

Upvotes: 4

Related Questions