android-java: check boolean value checking for null

Question

I am trying for null check like below

if (isTrue == null)

compile error says : "The operator == is undefined for the argument type(s) boolean"

Please help, how to do null check.

Thanks

Pablo Santa Cruz · Accepted Answer · 2011-10-29 11:33:33Z

19

You can't do null check on primitive types. boolean is a primitive type.

If you absolutely need to represent a null value with a boolean variable, you need to use the wrapper class java.lang.Boolean.

So, your example would be:

Boolean isTrue;
isTrue = null; // valid
isTrue = true; // valid
isTrue = false; // valid
if (isTrue == null) {
    // valid!
}

Here's the WIKIPEDIA entry for primitive wrapper classes.

answered Oct 29, 2011 at 11:33

Pablo Santa Cruz

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Comments

Sunny · Accepted Answer · 2011-10-29 11:36:20Z

7

The right way is

boolean isTrue;
if(!isTrue)

or

if(isTrue)

You can not check if the boolean is null or not.boolean must be true or false.

answered Oct 29, 2011 at 11:36

Sunny

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Comments

Steve Bergamini · Accepted Answer · 2011-10-29 11:33:31Z

4

A boolean is a primative type and cannot be null.

answered Oct 29, 2011 at 11:33

Steve Bergamini

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Théo Beaudenon · Accepted Answer · 2014-09-18 08:18:48Z

0

A boolean cannot be null in java.

A Boolean, however, can be null.

answered Sep 18, 2014 at 8:18

Théo Beaudenon

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