A programming kata is an exercise which helps a programmer hone his skills through practice and repetition.

This article is part of the series Java Tutorial Through Katas.

Fizz Buzz (Easy) – Java 7
Berlin Clock (Easy) – Java 7 and 8
Tennis Game (Easy) – Java 7
Reverse Polish Notation (Medium) – Java 7 and 8

The article assumes that the reader already has experience with Java, that he is familiar with the basic usage of JUnit tests and that he knows how to run them from his favorite IDE (ours is IntelliJ IDEA).

Tests that prove that the solution is correct are displayed below. Recommended way to solve this kata is to use test-driven development approach (write the implementation for the first test, confirm that it passes and move to the next). Once all of the tests pass, the kata can be considered solved.

One possible solution is provided below the tests. Try to solve the kata by yourself first.

Fizz Buzz

Return “fizz”, “buzz” or “fizzbuzz”.

For a given natural number greater than zero return:

• “fizz” if the number is dividable by 3
• “buzz” if the number is dividable by 5
• “fizzbuzz” if the number is dividable by 15
• the same number if no other requirement is fulfilled

[TESTS]

public class FizzBuzzTest {

    @Test
    public void getResultShouldReturnFizzIfTheNumberIsDividableBy3() {
        Assert.assertEquals("fizz", FizzBuzz.getResult(3));
    }

    @Test
    public void getResultShouldReturnBuzzIfTheNumberIsDividableBy5() {
        Assert.assertEquals("buzz", FizzBuzz.getResult(5));
        Assert.assertEquals("buzz", FizzBuzz.getResult(10));
    }

    @Test
    public void getResultShouldReturnBuzzIfTheNumberIsDividableBy15() {
        Assert.assertEquals("fizzbuzz", FizzBuzz.getResult(15));
        Assert.assertEquals("fizzbuzz", FizzBuzz.getResult(30));
    }

    @Test
    public void getResultShouldReturnTheSameNumberIfNoOtherRequirementIsFulfilled() {
        Assert.assertEquals("1", FizzBuzz.getResult(1));
        Assert.assertEquals("2", FizzBuzz.getResult(2));
        Assert.assertEquals("4", FizzBuzz.getResult(4));
    }

}

Test code can be found in the GitHub FizzBuzzTest.java.

[ONE POSSIBLE SOLUTION]

public class FizzBuzz {

    public static String getResult(int number) {
        if (number % 15 == 0) return "fizzbuzz";
        else if (number % 3 == 0) return "fizz";
        else if (number % 5 == 0) return "buzz";
        return Integer.toString(number);
    }

}

Java solution code can be found in the FizzBuzz.java solution.

What was your solution? Post it as a comment so that we can compare different ways to solve this kata.

Test-Driven Java Development

Test-Driven Java Development book wrote by Alex Garcia and me has been published by Packt Publishing. It was a long, demanding, but very rewarding journey that resulted in a very comprehensive hands-on material for all Java developers interested in learning or improving their TDD skills.

If you liked this article I am sure that you’ll find this book very useful. It contains extensive tutorials, guidelines and exercises for all Java developers eager to learn how to successfully apply TDD practices.

You can download a sample or purchase your own copy directly from Packt or Amazon.