How to check a Long for null in java

Question

How do I check a Long value for null in Java?

Will this work?

if ( longValue == null) { return blah; }

Ian Boyd · Accepted Answer · 2022-07-13 18:36:40Z

115

Primitive data types cannot be null. Only Object data types can be null.

There are 8 primitive types in Java:

Data Type	Size	Description
byte	1 byte	Int8
short	2 bytes	Int16
int	4 bytes	Int32
long	8 bytes	Int64
float	4 bytes	Single
double	8 bytes	Double
boolean	1 bit	Boolean

If you use Long (wrapper class for long) then you can check for null's:

Long longValue = null;

if(longValue == null)

edited Jul 13, 2022 at 18:36

Ian Boyd

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answered Oct 29, 2014 at 18:31

brso05

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Diablo · Accepted Answer · 2021-09-22 10:17:03Z

21

If it is Long object then You can use longValue == null or you can use Objects.isNull(longValue) method in Java 7+ projects .

Please check Objects for more info.

edited Sep 22, 2021 at 10:17

answered Mar 10, 2016 at 14:39

Diablo

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M A · Accepted Answer · 2014-10-29 18:44:05Z

12

If the longValue variable is of type Long (the wrapper class, not the primitive long), then yes you can check for null values.

A primitive variable needs to be initialized to some value explicitly (e.g. to 0) so its value will never be null.

edited Oct 29, 2014 at 18:44

answered Oct 29, 2014 at 18:31

M A

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Arif Ulusoy · Accepted Answer · 2014-10-29 18:50:08Z

10

You can check Long object for null value with longValue == null , you can use longValue == 0L for long (primitive), because default value of long is 0L, but it's result will be true if longValue is zero too

answered Oct 29, 2014 at 18:50

Arif Ulusoy

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Comments

Srinath · Accepted Answer · 2019-01-25 02:39:12Z

3

Of course Primitive types cannot be null. But in Java 8 you can use Objects.isNull(longValue) to check. Ex. If(Objects.isNull(longValue))

answered Jan 25, 2019 at 2:39

Srinath

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tammo · Accepted Answer · 2018-10-01 12:27:13Z

2

As mentioned already primitives can not be set to the Object type null.

What I do in such cases is just to use -1 or Long.MIN_VALUE.

answered Oct 1, 2018 at 12:27

tammo

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Niraj · Accepted Answer · 2020-05-12 05:54:16Z

0

If it is Long you can check if it's null unless you go for long (as primitive data types cant be null while Long instance is a object)

Long num; 

if(num == null) return;

For some context, you can also prefer using Optional with it to make it somehow beautiful for some use cases. Refer @RequestParam in Spring MVC handling optional parameters

answered May 12, 2020 at 5:54

Niraj

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Pavithra · Accepted Answer · 2018-07-30 06:10:33Z

-7

As primitives(long) can't be null,It can be converted to wrapper class of that primitive type(ie.Long) and null check can be performed.

If you want to check whether long variable is null,you can convert that into Long and check,

long longValue=null;

if(Long.valueOf(longValue)==null)

edited Jul 30, 2018 at 6:10

answered Jun 22, 2017 at 6:38

Pavithra

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1 Comment

Vitalii Diravka Over a year ago

You will never get null value for Long.valueOf() operation.

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