Avoid nested if for null and parameter condition

Question

Is it possible to avoid nested if statements while I want to check if variable/object is null and if variable/object meet some condition eg.

var obj = "test";
if (obj != null) {
   if (obj.equals("test")) {
      //do something;
   }
}

Is it possible to do oneliner of this statement without defining own method which handle this ?

"will obviously fail if obj is null." - Have you tried it?.. — Sayse, Oct 20 '16 at 08:05
Yes, it's called short-circuiting. Check this: http://stackoverflow.com/questions/8759868/java-logical-operator-short-circuiting — uoyilmaz, Oct 20 '16 at 08:06

score 4 · Accepted Answer · answered Oct 20 '16 at 08:03

4

You can also try (in Java)

"test".equals(obj)

this way, you don't have to do an explicit null check,

answered Oct 20 '16 at 08:03

user140547

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score 2 · Answer 2 · edited May 23 '17 at 12:06

You could make use of the null-conditional operator ? and the null-coalescing operator ??:

if(obj?.Equals("test") ?? false)
{
   // do something
}

Where obj?.Equals("test") returns null if obj is null and ?? assigns false to the if-statement if the value befor ?? is null.

But sadly this will only work in C#, not in Java. Java only knows the conditional operator ? but not the null-coalescing operator ?? (is there a Java equivalent to null coalescing operator (??) in C#?).

score 1 · Answer 3 · edited Jun 20 '20 at 09:12

I suggest you to get familiar with short-circuit of conditional statements

If you will call your conditions with && as following:

if (obj != null && obj.Equals("test"))
{
    //do something;
}

You will not get an exception, because if obj == null it will return false on the first parameter and will not check the second parameter of && statement.

The same logic is implemented in || - if first argument is true another arguments will not be checked.

Short-circuiting is also implemented in java, so you can implement nested ifs as the sequence of && operators both in c# and java.

sujith karivelil · Answer 4 · 2016-10-20T08:05:34.303

0

Use Logical && instead for nesting if. The && will evaluate the second condition only when the first one is true(the same thing that the nested if doing). So obj.equals("test") will be evaluated only when the first condition is true ie., obj!=null

if(obj!=null && obj.equals("test"))
{
   // do something;
}

edited Oct 20 '16 at 08:05

answered Oct 20 '16 at 08:01

sujith karivelil

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this will throw null exception if obj ==null – user2925656 Oct 20 '16 at 08:01
No, it won't because he is using && – Pepernoot Oct 20 '16 at 08:03
@user2925656 : The operation x && y corresponds to the operation x & y, except that y is evaluated only if x is true. – sujith karivelil Oct 20 '16 at 08:04

score 0 · Answer 5 · answered Oct 20 '16 at 08:01

0

Yes, you can.

But check for null should be first, then if your object is null it would break:

var obj = "test";
if(obj != null && obj.equals("test")){
    // do something;
}

answered Oct 20 '16 at 08:01

Markiian Benovskyi

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score 0 · Answer 6 · answered Oct 20 '16 at 08:05

0

operator && can permit you to do that.

if(obj!=null && obj.equals("test")){
    //do something
}

answered Oct 20 '16 at 08:05

Don Diego

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Avoid nested if for null and parameter condition

6 Answers6