Java int cannot be null

How to check int variable is null in Java ??

Hi everyone, I am new in Java programming. I want to know that how to check integer variable whether it is null or not. I have a situation I write a program that asks that how old are you. If a person accidentally press enter and does not put a value, I give a message that age can’t be null. I hope someone will help .
Regards

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There are ints and there are Integers (there is no Java data type called integer). One is a primitive value, the other is an Object. int variables cannot be null, but Integer variables can be.
What you get when the user presses Enter depends on what method you are using. …

Integers cannot be null, so I assume you mean you get null from your input method.

Post your code and perhaps someone can advise you on how to deal with the issue.

Edit: Sorry, post collision with James.

another approach would be:

1. set int age to -1;
2. input age;
3. if age < 0
no age or invalid age given by user
else
run application

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There are ints and there are Integers (there is no Java data type called integer). One is a primitive value, the other is an Object. int variables cannot be null, but Integer variables can be.
What you get when the user presses Enter depends on what method you are using. Please post the relevant part of your code.

Integers cannot be null, so I assume you mean you get null from your input method. Post your code and perhaps someone can advise you on how to deal with the issue. Edit: Sorry, post collision with James.

There are ints and there are Integers (there is no Java data type called integer). One is a primitive value, the other is an Object. int variables cannot be null, but Integer variables can be.
What you get when the user presses Enter depends on what method you are using. Please post the relevant part of your code.

Thanks for reply! I learn from you that int and Integers are different things. My program is here, please check it and reply.

int age; Scanner a = new Scanner(System.in); //I want to check that if someone did not enter value do while loop again asks same question. do< System.out.println("What is your age ?"); age = a.nextInt(); if(age == null) System.out.println("Age cannot be null"); >while(age == null);

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Can an Int Be Null in Java

int can’t be null, but Integer can. You need to be careful when unboxing null Integers since this can cause a lot of confusion and head scratching!

int a = object.getA(); // getA returns a null Integer

will give you a NullPointerException , despite object not being null!

To follow up on your question, if you want to indicate the absence of a value, I would investigate java.util.Optional

why int can’t be compared to null but Integer can be compared to null

int a,b,c;
if (a == null) //code here
>

This code doesn’t make sense, because primitive int types cannot be null. Even if you considered auto-boxing, int a is guaranteed to have a value before being boxed.

Integer a,b,c;
if (a == null) //code here
>

This code makes sense, because Object Integer types can be null (no value).

As far as the functionality, the Object vs built-in types actually do make a bit of a difference (due to their different natures).

Integer a,b,c;
if (a == b) // a and b refer to the same instance. 
// for small integers where a and b are constructed with the same values, 
// the JVM uses a factory and this will mostly work 
// 
// for large integers where a and b are constructed with the same values, 
// you could get a == b to fail
>

int a,b,c;
if (a == b) // for all integers were a and b contain the same value, 
// this will always work
>

How to set to int value null? Java Android

In this case, I would avoid using null all together.

If you need -1 to be an acceptable (not null) value, then use a float instead. Since all your real answers are going to be integers, make your null 0.1

Or, find a value that the x will never be, like Integer.MAX_VALUE or something.

Can not set int field to null value

The primitive datatype int isn’t nullable. You need to use the Wrapper class Integer in this case. So just replace the type.

Setting null value to integer

I am sure you are over-complicating the problem, it is a real simple thing to do. Check the code below:

Integer i = null;
System.out.println(i == null ?"":i);

How to check if an int is a null

An int is not null, it may be 0 if not initialized.

If you want an integer to be able to be null, you need to use Integer instead of int .

Integer id;
String name;

public Integer getId()

Besides, the statement if(person.equals(null)) can’t be true because if person is null, then a NullPointerException will be thrown. So the correct expression is if (person == null)

How to assign a null value to a single element in an int[] array in Java

Primitive Java integers cannot be null , but the Integer class, which wraps a primitive int can be null . Here is one option to consider:

Integer[] num = new Integer[3];
num[0] = 23;
num[1] = null;
num[2] = 12;

The boxing rules in Java make it fairly easy to use int and Integer interchangeably, most of the time.

How to accept an empty integer value?

Change your variable types to the wrapper classes(Integer, Double) of primitive types(int, double). In Java, primitive types cannot be null.

How to check whether an Integer is null or zero in Java?

Since StringUtils class is mentioned in the question, I assume that Apache Commons lib is already used in the project.

Then you can use the following:

if (0 != ObjectUtils.defaultIfNull(myInteger, 0))
if (0 != defaultIfNull(myInteger, 0))

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Check if Int Is Null in Java

In this guide, we will learn how to check if int is null in java. In order to understand this concept, we need to go through some basic understanding of datatype int . Let’s dive in.

Can int Be Null in Java?

One thing that we need to understand first is that int is a primitive data type. Such data types stores data in binary form in memory by default. That means they can’t be null. We certainly can’t check int for a null value. On the other hand, we can’t confuse it with the Integer which is an object and which can have a null value. An Integer is a wrapper class of int that allows the developers to have more functionalities associated with int . This is the difference that you need to understand, learn more about int and Integerhere.

public class Main   public static void main(String[] args)    int id=0; // Primitve DataTypes..  Integer ID = new Integer(5);  System.out.println( "Primitive integer : "+ id);  // we cannot check for Null Property  System.out.println( "Integer Object : "+ ID);  // We can check for Null Property..   if(ID==null)    System.out.println("Integer Is Null");  >  else    System.out.println("Integer Is Not Null");  >   > > 

Primitive integer : 0 Integer Object : 5 Integer Is Not Null 

As seen in the above example, int cannot be null. On the other hand, Integer is an object which can be checked for the null property.

Haider specializes in technical writing. He has a solid background in computer science that allows him to create engaging, original, and compelling technical tutorials. In his free time, he enjoys adding new skills to his repertoire and watching Netflix.

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