Java .multiplyExact()

The .multiplyExact() method returns the product of its arguments.

Syntax

Math.multiplyExact(x, y)

The .multiplyExact() method takes two parameters: x and y (a multiplicand and multiplier). Both parameters must be of either type int or long.

The .multiplyExact() method returns the result of x multiplied by y.

An exception is thrown if the result exceeds type int or long or is equal to:

• Integer.MAX_VALUE
• Integer.MIN_VALUE
• Long.MAX_VALUE
• Long.MIN_VALUE

Example

In the following example, the .multiplyExact() method first returns the product of two numbers and then throws an exception:

// Main.java
public class Main {
  public static void main(String[] args) {
    int num1 = 8;
    int num2 = 2;
    /*
    Returns the product of the two numbers
    */
    System.out.println(num1 + " multiplied by " + num2 + " equals to " + Math.multiplyExact(num1, num2));

    long c = 299792458;
    long m = Long.MAX_VALUE;
    /*
    Overflow will occur if any one of the arguments is
    Long.MAX_VALUE or Integer.MAX_VALUE.
    */
    System.out.println(Math.multiplyExact(c, m));
  }
}

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This will produce the following output:

8 multiplied by 2 equals to 16
Exception in thread "main" java.lang.ArithmeticException: long overflow
        at java.base/java.lang.Math.multiplyExact(Math.java:946)
        at Main.main(Main.java:17)

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