Integer too long Java

Question

  public static void gramstoAtoms()
  {
   System.out.println("Enter Amount of grams");
   Scanner keyboard = new Scanner(System.in);
   long x = keyboard.nextLong();
   System.out.println("Enter Unit Grams");
   long y = keyboard.nextLong();
   long result = x/y;
   long answer = result*60200000000000000000000;
   System.out.println(answer + "Atoms");
  }

How do I change this code so that I don't get an integer is too long error?

http://stackoverflow.com/questions/8924896/java-long-number-too-large-error — , May 09 '13 at 12:59
Use Big integer : http://stackoverflow.com/questions/1783912/java-how-to-use-biginteger — William Falcon, May 09 '13 at 13:00
Or BigDecimal, given that your division should probably be not be an integer division. Multiplying a truncation error by such a large number will give a totally incorrect response — JB Nizet, May 09 '13 at 13:00
If you don't need a very precise answer a `double` is more suitable. — kennytm, May 09 '13 at 13:03

Dima · Accepted Answer · 2013-05-09T13:07:35.513

7

just use BigInteger instead of long

BigInteger bi=new BigInteger("6020000000000000000000");

for your method:

public static void gramstoAtoms()
  {
   System.out.println("Enter Amount of grams");
   Scanner keyboard = new Scanner(System.in);
   String x = keyboard.nextLine();
   System.out.println("Enter Unit Grams");
   String y = keyboard.nextLine();
   BigInteger result = new BigInteger(x).divide(new BigInteger(y));
   BigInteger answer = result.multiply(new BigInteger("60200000000000000000000"));
   System.out.println(answer + "Atoms");
  }

and if your x and y are small, you can use them with simple long, but when multiply by the 602.......0000 use the BigInteger

edited May 09 '13 at 13:07

answered May 09 '13 at 13:00

Dima

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what do i need to import for the class, because it gives me this: – user2362569 May 09 '13 at 13:04
import java.math.BigInteger; – Dima May 09 '13 at 13:05
It compiles, however it does not multiply the result – user2362569 May 09 '13 at 13:07
my output: Enter Amount of grams 5 Enter Unit Grams 2 120400000000000000000000Atoms – Dima May 09 '13 at 13:08
Try gram = 45 and unit gram = 23 – user2362569 May 09 '13 at 13:11
Grams = 6 and unit gram = 7 gives me 0 too – user2362569 May 09 '13 at 13:13
this is because this is integers and not doubles, try first multiply by the big number and then divide it, because 45/23 gives 1.9 ant it takes the floor of it – Dima May 09 '13 at 13:14
Thank you so much, this code works very well now. – user2362569 May 09 '13 at 13:18

score 3 · Answer 2 · answered May 09 '13 at 13:01

3

If I recall correctly, Avogadro's number is 6.02e24. A long has a max value of 9,223,372,036,854,775,807, which isn't big enough. You'll need BigInteger.

answered May 09 '13 at 13:01

duffymo

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How do I put in BigInteger into the code, it gives me a compile error. – user2362569 May 09 '13 at 13:03

score 1 · Answer 3 · answered May 09 '13 at 13:13

1

It's a solution without BigInteger:

long answer = result * 602;
System.out.println(answer + "00000000000000000000Atoms");

answered May 09 '13 at 13:13

johnchen902

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I was about to write this. If you always expect to have so many zeros at the end, why bother handling such big numbers? – MMM May 09 '13 at 13:21
@MMM The question *expects* to have so many zeros, according to the code he provides. I still use `BigInteger` when necessary. – johnchen902 May 09 '13 at 13:27
That's what I'm saying. – MMM May 09 '13 at 13:29

score 0 · Answer 4 · answered May 09 '13 at 13:21

0

Dima Goltsman is correct, you had to fix it using the BigInteger

answered May 09 '13 at 13:21

Splash City

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Integer too long Java

4 Answers4