Java Control Flow Practice

Practise if/else, switch expressions, for and while loops, nested loops, break and continue in Java.

Beginner7 problemsUpdated October 23, 2026

Review first: if, else if and else, switch and switch Expressions, Loops: for, while, do-while, for and Enhanced for, while and do-while, break and continue

1.Marks to grades

Beginner

For each mark in {95, 82, 67, 45, 74}, print the mark and its grade: A for 90+, B for 75–89, C for 60–74 and F below 60.

Show hint

Use an if / else if chain from the highest grade down.

Show solution

Java

public class Main {
    public static void main(String[] args) {
        int[] marks = {95, 82, 67, 45, 74};
        for (int m : marks) {
            char grade;
            if (m >= 90) {
                grade = 'A';
            } else if (m >= 75) {
                grade = 'B';
            } else if (m >= 60) {
                grade = 'C';
            } else {
                grade = 'F';
            }
            System.out.println(m + " " + grade);
        }
    }
}

Output

95 A
82 B
67 C
45 F
74 C

2.FizzBuzz

Beginner

Print 1 to 15 on one line, separated by spaces, with Fizz for multiples of 3, Buzz for multiples of 5 and FizzBuzz for multiples of both.

Show hint

Check n % 15 == 0 first. A StringBuilder builds the line.

Show solution

Java

public class Main {
    public static void main(String[] args) {
        StringBuilder line = new StringBuilder();
        for (int n = 1; n <= 15; n++) {
            if (n > 1) line.append(' ');
            if (n % 15 == 0) line.append("FizzBuzz");
            else if (n % 3 == 0) line.append("Fizz");
            else if (n % 5 == 0) line.append("Buzz");
            else line.append(n);
        }
        System.out.println(line);
    }
}

Output

1 2 Fizz 4 Buzz Fizz 7 8 Fizz Buzz 11 Fizz 13 14 FizzBuzz

3.Weekday or weekend

Beginner

Days are numbered 1 (Monday) to 7 (Sunday). For 1, 6, 7 and 9, print weekday, weekend or invalid using a switch expression.

Show hint

Arrow cases can list several labels: case 1, 2, 3, 4, 5 -> "weekday";.

Show solution

Java

public class Main {
    public static void main(String[] args) {
        for (int day : new int[] {1, 6, 7, 9}) {
            String kind = switch (day) {
                case 1, 2, 3, 4, 5 -> "weekday";
                case 6, 7 -> "weekend";
                default -> "invalid";
            };
            System.out.println(day + ": " + kind);
        }
    }
}

Output

1: weekday
6: weekend
7: weekend
9: invalid

4.Digit sum and reverse

Beginner

For n = 50721, use a while loop to print the sum of its digits and the number reversed.

Show hint

Take the last digit with n % 10, remove it with n /= 10, and build the reverse with reversed * 10 + digit.

Show solution

Java

public class Main {
    public static void main(String[] args) {
        int n = 50721;
        int sum = 0;
        int reversed = 0;
        while (n > 0) {
            int digit = n % 10;
            sum += digit;
            reversed = reversed * 10 + digit;
            n /= 10;
        }
        System.out.println(sum + " " + reversed);
    }
}

Output

15 12705

5.First common multiple

Beginner

Find the first number greater than 100 that is divisible by both 7 and 11, using a loop with break.

Show hint

Count upwards from 101 and break as soon as both remainders are 0.

Show solution

Java

public class Main {
    public static void main(String[] args) {
        int n = 101;
        while (true) {
            if (n % 7 == 0 && n % 11 == 0) break;
            n++;
        }
        System.out.println(n);
    }
}

Output

6.Star pyramid

Beginner

Print a centred pyramid of stars with 4 rows: row r has 4 - r spaces and 2r - 1 stars.

Show hint

" ".repeat(n) and "*".repeat(n) (Java 11) build each part of a row.

Show solution

Java

public class Main {
    public static void main(String[] args) {
        int height = 4;
        for (int r = 1; r <= height; r++) {
            System.out.println(" ".repeat(height - r) + "*".repeat(2 * r - 1));
        }
    }
}

Output

   *
  ***
 *****
*******

7.Skip the negatives

Beginner

Add up only the positive numbers in {5, -2, 8, -7, 3}, using continue to skip the others.

Show hint

if (x < 0) continue; at the top of the loop body.

Show solution

Java

public class Main {
    public static void main(String[] args) {
        int total = 0;
        for (int x : new int[] {5, -2, 8, -7, 3}) {
            if (x < 0) continue;
            total += x;
        }
        System.out.println(total);
    }
}

Output

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