CODEWITHSUNDEEP
javac#
user2925656
user2925656

Reputation: 393

Avoid nested if for null and parameter condition

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 ?

Upvotes: 2

Views: 1693

Answers (6)

croxy
croxy

Reputation: 4168

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#?).

Upvotes: 2

Mikhail Tulubaev
Mikhail Tulubaev

Reputation: 4261

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.

Upvotes: 1

sujith karivelil
sujith karivelil

Reputation: 29026

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;
}

Upvotes: 0

Don Diego
Don Diego

Reputation: 1488

operator && can permit you to do that.

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

Upvotes: 0

user140547
user140547

Reputation: 8200

You can also try (in Java)

"test".equals(obj)

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

Upvotes: 4

Markiian Benovskyi
Markiian Benovskyi

Reputation: 2161

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;
}

Upvotes: 0

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