How to check if number is above Integer.MAX_VALUE in Java, when adding to it some other number?

Question

I have a problem when I add some number to the maximum of Integer, I am no longer above the maximum because the number changes to Integer.MIN_VALUE + added valued -1, how should I than check it ? `

        int max = Integer.MAX_VALUE;
        int x = max +100;
        if (x > max){
            System.out.println(x + "x is not bigger, so it wont be printed.");

        }


    }
}`

Answer 1

One way would be to test it as a long.

            int max = 2292292;
            int x = 100;
            if ((x + (long)max) != (x + max)) {
                System.out.println("Overflow on x so it wont be printed.");
            } else {
                x = max + 100; 
            }

Answer 2

There are a couple of methods depending on what you want to do.

1. If you are looking to add a number to an int and want to know if it overflows, then use Math.addExact . It throws an ArithmeticException which you can catch if you want to take action.

2. If you want to safely add a value and then compare to Integer.MAX_VALUE then use a long instead. By definition no int is ever larger than the maximum value.

So I'd suggest

try {
    int x = Math.addExact(Integer.MAX_VALUE, 100);
} catch (ArithmeticException ex) {
    System.out.println("x has overflowed");
}