What is Math.decrementExact() in Java?

The decrementExact method in Java decrements the value passed as an argument by 1, and then returns the decremented value. The value stored in the passed variable is unchanged.

The arguments will be either int or long. decrementExact is a static method present in the Math class.

Syntax

public static long decrementExact(long a);

public static int decrementExact(int a);

Arguments

  • a: Value to decrement (int/long).

Return value

This function returns the decremented value of a, i.e, a-1.

Example

import java.lang.Math;
class DecrementExact {
    public static void main(String cmdArgs[]) {
        int a = 10;
        int decrementedValue = Math.decrementExact(a);
        System.out.print("The decreamented value of "+ a + " is ");
        System.out.println(decrementedValue);
        long la = 100000000l;
        long lDecrementedValue = Math.decrementExact(la);
        System.out.print("The decreamented value of "+ la + " is ");
        System.out.println(lDecrementedValue);
    }
}

In the code above:

  • We created two variables, a of the int type and la of the long type.

  • We called the Math.decrementExact method with a as arguments. This will return the decrement of the value of a by 1. In our case, the value of a=10, so decrementExact will return 9. The value of a remains unchanged as 10.

  • Again, we called the Math.decrementExact method with la as an argument. This will return the decrement of the value of la by 1. In our case, the value of la= 100000000, so decrementExact will return 99999999.

The decrementExact method will throw an ArithmeticException if:

  • The argument is int and the decrement of the argument overflows the int value.

  • The argument is long and the decrement of the argument overflows the long value.

Example

For example, consider if the argument is int. The ArithmeticException will be thrown if the decrement of the int argument is less than the minimum value or greater than the maximum value that the int type can hold.

import java.lang.Math;
class DerementExactTest {
    public static void main(String cmdArgs[]) {
        try{
            int a = Integer.MIN_VALUE;
            int decrementedVal = Math.decrementExact(a);
        }catch(Exception e){
            System.out.println(e);
        }
        
    }
}

In the code above, we created a variable, a of the int type. We assigned the minimum value an integer can hold to the variable a.

When we call the decrementExact method with a as an argument, we will get ArithmeticException. This is because when we decrement the value of a, the value will be less than the minimum value an integer can hold.

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