MIT-Curricular/OOP/Java/Lab/Week5/Number.java

import java.util.Scanner;

class Number {

    private double value;

    public Number(double value) {
        this.value = value;
    }

    public boolean isZero() {
        return value == 0;
    }

    public boolean isPositive() {
        return value > 0;
    }

    public boolean isNegative() {
        return value < 0;
    }

    public boolean isOdd() {
        return (int) value % 2 != 0;
    }

    public boolean isEven() {
        // This is an explicit narrowing typecast from double to int
        return (int) value % 2 == 0;
    }

    public boolean isPrime() {
        if (value <= 1 || value != (int) value) return false;
        for (int i = 2; i <= Math.sqrt(value); i++) if (
            (int) value % i == 0
        ) return false;
        return true;
    }

    public boolean isArmstrong() {
        if (value != (int) value) return false;
        int num = (int) value, sum = 0, digits = String.valueOf(num).length();
        for (int n = num; n > 0; n /= 10) sum += Math.pow(n % 10, digits);
        return sum == num;
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter a number: ");
        Number number = new Number(sc.nextDouble());

        System.out.println(
            "Is Zero: " +
            number.isZero() +
            ", Is Positive: " +
            number.isPositive() +
            ", Is Negative: " +
            number.isNegative() +
            ", Is Odd: " +
            number.isOdd() +
            ", Is Even: " +
            number.isEven() +
            ", Is Prime: " +
            number.isPrime() +
            ", Is Armstrong: " +
            number.isArmstrong()
        );

        sc.close();
    }
}