Practice Questions — Operators in Java

public class SimpleInterest {
    public static void main(String[] args) {
        int principal = 50000;
        double rate = 8.5;
        int time = 3;
        double interest = (principal * rate * time) / 100;
        System.out.println("Principal: " + principal);
        System.out.println("Rate: " + rate + "%");
        System.out.println("Time: " + time + " years");
        System.out.println("Simple Interest: " + interest);
    }
}

public class EvenOddChecker {
    public static void main(String[] args) {
        int n = 42;
        System.out.println("Number: " + n);
        System.out.println("Method 1 (modulus): " + (n % 2 == 0 ? "even" : "odd"));
        System.out.println("Method 2 (bitwise): " + ((n & 1) == 0 ? "even" : "odd"));
        String result = (n % 2 == 0) ? "even" : "odd";
        System.out.println("Method 3 (ternary): " + result);
    }
}

public class DigitExtractor {
    public static void main(String[] args) {
        int num = 5821;
        int thousands = num / 1000;
        int hundreds = (num / 100) % 10;
        int tens = (num / 10) % 10;
        int ones = num % 10;
        System.out.println("Number: " + num);
        System.out.println("Thousands: " + thousands);
        System.out.println("Hundreds: " + hundreds);
        System.out.println("Tens: " + tens);
        System.out.println("Ones: " + ones);
    }
}

public class LeapYear {
    public static void main(String[] args) {
        int y1 = 2024, y2 = 2100, y3 = 2000;
        boolean leap1 = (y1 % 4 == 0) && (y1 % 100 != 0 || y1 % 400 == 0);
        boolean leap2 = (y2 % 4 == 0) && (y2 % 100 != 0 || y2 % 400 == 0);
        boolean leap3 = (y3 % 4 == 0) && (y3 % 100 != 0 || y3 % 400 == 0);
        System.out.println(y1 + " is a leap year: " + leap1);
        System.out.println(y2 + " is a leap year: " + leap2);
        System.out.println(y3 + " is a leap year: " + leap3);
    }
}

public class PowerOfTwo {
    public static void main(String[] args) {
        int[] nums = {1, 2, 4, 6, 8, 16, 15, 32, 100, 1024};
        for (int n : nums) {
            boolean isPowerOf2 = n > 0 && (n & (n - 1)) == 0;
            System.out.println(n + " is power of 2: " + isPowerOf2);
        }
    }
}

public class SetBitCounter {
    public static void main(String[] args) {
        int[] nums = {42, 255};
        for (int num : nums) {
            int count = 0;
            int temp = num;
            while (temp > 0) {
                count += temp & 1;
                temp >>= 1;
            }
            System.out.println(num + " in binary: " + Integer.toBinaryString(num));
            System.out.println("Set bits in " + num + ": " + count);
        }
    }
}

public class PrecedencePuzzle {
    public static void main(String[] args) {
        // a) 2*3=6, 4/2=2, 10+6-2=14
        System.out.println("a) 10 + 2*3 - 4/2 = " + (10 + 2 * 3 - 4 / 2));
        // b) 15%4=3, 2*3=6, 3+6=9
        System.out.println("b) 15%4 + 2*3 = " + (15 % 4 + 2 * 3));
        // c) !true=false, false&&false=false, true||false=true
        System.out.println("c) true || false && !true = " + (true || false && !true));
        // d) + has higher precedence than <<! So 1+2=3, then 5<<3=40
        System.out.println("d) 5 << 1+2 = " + (5 << 1 + 2));
        // e) 10>5 is true, so 2+3=5
        System.out.println("e) 10>5 ? 2+3 : 4*5 = " + (10 > 5 ? 2 + 3 : 4 * 5));
    }
}

public class GradeAssigner {
    public static void main(String[] args) {
        int[] marks = {95, 82, 71, 63, 55, 42, 35};
        for (int m : marks) {
            String grade = (m >= 90) ? "A+" :
                           (m >= 80) ? "A" :
                           (m >= 70) ? "B+" :
                           (m >= 60) ? "B" :
                           (m >= 50) ? "C" :
                           (m >= 40) ? "D" : "F";
            System.out.println(m + "% -> " + grade);
        }
    }
}