CODEWITHSUNDEEP
java
Aditya
Aditya

Reputation: 1043

Java Integer Max Range multiplication

Integer num = 2147483647;
Integer res =  num * num;
System.out.println(res);

The Out put for above is 1. Am not sure why. Can someone please explain.

Thanks in advance.

Upvotes: 1

Views: 1360

Answers (4)

Evgeniy Dorofeev
Evgeniy Dorofeev

Reputation: 136102

This is supposed to demonstrate why result = 1:

    long x = Integer.MAX_VALUE;
    long y = Integer.MAX_VALUE;
    long res = x * y;
    System.out.println(Long.toHexString(res));

prints

3fffffff00000001

if we cast res to int we will get 1

Upvotes: 1

SMA
SMA

Reputation: 37083

That's because it overflows the range of integer and even long which is between -2,147,483,648 and a maximum value of 2,147,483,647 (inclusive).

You should try using BigInteger if that's the case like:

String num = "2147483647";
BigInteger mult = new BigInteger(num);
System.out.println(mult.multiply(mult));

Upvotes: 0

Bhargav Modi
Bhargav Modi

Reputation: 2655

this because of the flag value
0: iconst_0
1: istore_1

As the limit is out of range for Integer it will set the flag of 1 for more about how it works use this link

Upvotes: 0

Arpit Aggarwal
Arpit Aggarwal

Reputation: 29316

It's because of Integer overflow. Java has a minimum value of -2,147,483,648 and a maximum value of 2,147,483,647 (inclusive) and your result(res) is beyond Integer max range.

Upvotes: 0

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