Simplify null checkiing when using Java

Question

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

Which java version is in use?

Fildor
– Fildor

2016-02-17 06:34:26 +00:00
Commented Feb 17, 2016 at 6:34 — Fildor
– Fildor, Commented Feb 17, 2016 at 6:34

TheLostMind · Accepted Answer · 2016-02-17 06:43:11Z

4

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));

edited Feb 17, 2016 at 6:43

answered Feb 17, 2016 at 6:38

TheLostMind

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2 Comments

mmuzahid Over a year ago

obj1.getObj2().getObj3().getObj4() should not always return string. I think rewrite obj1.getObj2().getObj3().getObj4().toString();

TheLostMind Over a year ago

@mmuzahid - Yes. That code is untested. I had missed the semi-colon too :P

Jörn Buitink · Accepted Answer · 2016-02-17 06:36:25Z

4

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.

answered Feb 17, 2016 at 6:36

Jörn Buitink

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Comments

edge · Accepted Answer · 2016-02-17 06:36:52Z

2

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());
}

answered Feb 17, 2016 at 6:36

edge

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Comments

Jim Garrison · Accepted Answer · 2016-02-17 06:51:08Z

2

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

answered Feb 17, 2016 at 6:51

Jim Garrison

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Comments

Hauleth · Accepted Answer · 2016-02-17 07:34:10Z

0

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.

answered Feb 17, 2016 at 7:34

Hauleth

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