Math utilities

Key points

• Math is nothing but static methods over primitives — you never create one.
• abs, max, sqrt, pow and hypot cover the everyday cases.
• round ties upward: round(2.5) is 3 but round(-2.5) is -2.
• floor and ceil return doubles, while floorMod keeps negative numbers behaving like a clock.
• addExact throws ArithmeticException instead of silently wrapping — use it on money and counters.
• Math.random() returns a value in [0, 1). For bounded or repeatable values use java.util.Random.

Example

public class Main {
    public static void main(String[] args) {
        System.out.println("abs(-7)         = " + Math.abs(-7));
        System.out.println("max / min       = " + Math.max(3, 9) + " / " + Math.min(3, 9));
        System.out.println("pow(2, 10)      = " + Math.pow(2, 10) + "  (always a double)");
        System.out.println("sqrt(144)       = " + Math.sqrt(144));
        System.out.println("round(2.5)      = " + Math.round(2.5) + ", round(-2.5) = " + Math.round(-2.5));
        System.out.println("floor / ceil    = " + Math.floor(2.7) + " / " + Math.ceil(2.1));

        System.out.println("-7 / 2          = " + (-7 / 2) + " but floorDiv(-7, 2) = " + Math.floorDiv(-7, 2));
        System.out.println("-7 % 3          = " + (-7 % 3) + " but floorMod(-7, 3) = " + Math.floorMod(-7, 3));

        try {
            Math.addExact(Integer.MAX_VALUE, 1);
        } catch (ArithmeticException e) {
            System.out.println("addExact refuses to wrap: " + e.getMessage());
        }

        System.out.println("hypot(3, 4)     = " + Math.hypot(3, 4));
        System.out.println("PI              = " + String.format("%.5f", Math.PI));
        System.out.println("random() is in [0, 1): " + (Math.random() < 1.0));
    }
}

Math already solved it, and it handles the edge cases you would forget.