CODEWITHSUNDEEP
java
Jacek Kwiecień
Jacek Kwiecień

Reputation: 12637

Check if a double is infinite in Java

I'm making a simple calculator for this homework, and Java is returning "Infinity" when divided by 0.

I need to display some error message, when I get infinity. The problem is I don't know how to do the condition

double result;
result = 4/0;
//if result == infinity then some message - need help with this

Upvotes: 32

Views: 51283

Answers (7)

soulcheck
soulcheck

Reputation: 36767

You can use Double.isInfinite(double)

Here's double doc

Upvotes: 70

C-Mac
C-Mac

Reputation: 31

Resurrecting a super old question because it came up in my Java class. So I'm sure you tried the try/catch like they all suggested, but you found, like me, that it didn't work with Double. The try/catch with ArithmeticException doesn't work on Double or Float since they return "Infinity" instead of returning an exception. (note, delted myold "answer" since it wasn't an answer).

Piecing together a few different questions/answers on this, I came up with the following trials.

public class trial
{
  public static void main(String[] args)
  {
      double a;
     try {
          a = 4/0;
         System.out.println(" The answer is " +a);
      } catch(ArithmeticException e) {
     System.out.println(" You can't divide by zero. Please try again.");
      }
  }
}

The above code should give you the result "The answer is Infinity." At least it did for me since it is a double.

With an int, it would not need the below if statement since it would throw an exception. But since it is a Double, the if statement below will cause it to throw an exception which the catch will... well... catch.

public class trial
{
public static void main(String[] args)
  {
      double a;
          try {
        a = 4/0;
   // if statement to throw an AtithmeticException if ans equals infinity
      if(a == Double.POSITIVE_INFINITY){
          throw new ArithmeticException();

        }
        else{

          System.out.println(" The answer is " +a);
        }

  } catch(ArithmeticException e) {
     System.out.println(" You can't divide by zero. Please try again.");
    }
  }
}

Upvotes: 1

Nelson Katale
Nelson Katale

Reputation: 1539

Jacek Kwiecień try this code

double result;
try{
    result=4.0/0.0;
}catch(ArithmeticException e){

    System.out.println("Math error "+ e.getMessage())
}

`

Upvotes: 0

Thomas
Thomas

Reputation: 88707

There are two fields for infinity in the Double class: POSITIVE_INFINITY and NEGATIVE_INFINITY which you can check for.

Note that integer division by zero would throw an ArithmeticException thus your line would have to be 4.0/0, 4/0.0 or 4.0/0.0 since 4 and 0 are integers and thus result in integer math.

Upvotes: 2

gprathour
gprathour

Reputation: 15333

This kind of errors are called exceptions. You can use try-catch block to catch this exception.

 try{
      result = 4/0;
 }
 catch(ArithmeticException e){
     System.out.println("You divided by zero");
 }

you can read about exception handling here.

Upvotes: -1

Peter Lawrey
Peter Lawrey

Reputation: 533492

The above code produces

ArithmeticException: / by zero

You can catch this exception in a try/catch block.

Upvotes: 5

gd1
gd1

Reputation: 11403

Please see if it equal to Double.POSITIVE_INFINITY

double result;
result = 4.0 / 0.0;

Upvotes: 1

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