CODEWITHSUNDEEP
javanullpointerexceptiontostring
user3297173
user3297173

Reputation: 121

NullPointerException possibility in Integer.toString(arg) method in java

Is there any possibility that Integer.toString(args) give an NullPointerException like String.valueOf(args).

I know its Silly Question but I want to be clear that is there any possibility that Integer.toString() can give NullPointerException.

Upvotes: 7

Views: 11403

Answers (5)

Let'sRefactor
Let'sRefactor

Reputation: 3346

Integer.toString(args) may give an NullPointerException unlike String.valueOf(args). 

Integer i = null; 
Integer.toString(i);        // Null pointer exception!! 
String.valueOf(i);          // No exception 
i.toString();               // Again, Null pointer exception!!

See my experiment here : http://rextester.com/YRGGY86170

Upvotes: 6

Klitos Kyriacou
Klitos Kyriacou

Reputation: 11652

The answer is yes and no. It depends on how one interprets your question.

Is it possible for the expression var.toString() (or Integer.toString(var)) to throw a NullPointerException? Yes.

Can the method Integer.toString() (or Integer.toString(int)) ever throw a NullPointerException? No.

In var.toString(), a NullPointerException will be thrown if var is null. But the exception will be thrown by the current method, and toString() will not be called.

In Integer.toString(var), a NullPointerException will be thrown if var is null. But it is not the toString(int) method that throws it. If var is an Integer object, the expression is shorthand for

Integer.toString(var.intValue())

and so obviously if var is null, a NullPointerException will be thrown by the current method, and neither intValue() nor toString(int) will be called.

So to reiterate, toString() and toString(int) themselves never throw NullPointerException.

Upvotes: 2

Marvin
Marvin

Reputation: 14415

Technically yes, due to unboxing. Although I'm not sure if that is what you meant:

public class Test {

    public static void main(String[] args) {
        Integer i = null;
        System.out.println(Integer.toString(i)); // NullPointerException
    }
}

Upvotes: 3

Jesper
Jesper

Reputation: 206946

Do you mean the static method toString(int i) of class Integer? That method will never throw NullPointerException - there is no int value that you can pass that will ever produce a NullPointerException.

Upvotes: 1

samczsun
samczsun

Reputation: 1024

Integer#toString does not take any args, and only passes in the field value. value can never be null because you cannot pass a null int primitive and a null String will simply throw a NumberFormatException here

EDIT: I did not consider the toString methods which take an int, but the results will be the same - int can never be null so there will be no NPE

Upvotes: 0

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