FizzBuzz implementation

Question

The common FizzBuzz implementation I saw is using a check for % 15 for printing "FizzBuzz"

Would you let me know if there is anything wrong / better with this approach?

public class FizzBuzz {
    public static void main(String[] args) {
        for (int i = 1; i <= 100; i++) {
            boolean fizzOrBuzz = false;
            if (i % 3 == 0) {
                System.out.print("Fizz");
                fizzOrBuzz = true;
            }
            if (i % 5 == 0) {
                System.out.print("Buzz");
                fizzOrBuzz = true;
            }

            if (fizzOrBuzz) {
                System.out.println();
            } else {
                System.out.println(String.valueOf(i));
            }
        }
    }
}

Answer 1

Let's compare your version to the % 15 version:

public class FizzBuzz {
    public static void main(String[] args) {
        for (int i = 1; i <= 100; i++) {
            if (i % 15 == 0) {
                System.out.println("FizzBuzz")
            } else if (i % 3 == 0) {
                System.out.println("Fizz");
            } else if (i % 5 == 0) {
                System.out.println("Buzz");
            } else {
                System.out.println(String.valueOf(i));
            }
        }
    }
}

The % 15 version is simpler and easier to read. This version neatly delineates the problem into the 4 different cases, and handles each case. In contrast, your version introduces a boolean logic flag (which I consider to be a significant anti-pattern) and a not entirely intuitive dependence on the order of the if statements.

Answer 2

It looks fine. String.valueOf() is unnecessary, System.out.println(i) would print the same but it is still OK. This test is used only to make sure that the interviewee can write code as the linked site says:

This sort of question won’t identify great programmers, but it will identify the weak ones. And that’s definitely a step in the right direction.

Answer 3

They are certainly not perfects, but I've tried some ways to optimize the test, here the result (I have had numbers to keep trace of good responses) , and I use a StringBuilder to avoid initialization of output IO:

package exercices;

import java.util.Hashtable;

import org.memneuroo.outils.communs.utilitaires.EnvPrm;

public class FizzBuzz {
    // time for cum with nbIter=30 > 300; 30 ~= 3000
    static final int nbIter = 30;
    static final String sep = "_";

    static long ifNested() {
        final StringBuilder sb = new StringBuilder();
        final long t = System.nanoTime();
        for (int i = 0; i < nbIter; i++) {
            sb.append(//
            i % 15 == 0 //
                ? "FizzBuzz" //
                : (i % 3 == 0 //
                    ? "Fizz"//
                    : (i % 5 == 0//
                        ? "Buzz" //
                        : i)));// sb.append(sep);
        }
        final long totT = System.nanoTime() - t;
        System.out.format("ifNested\t%20d\n", totT);
        // sb.append(EnvPrm.NEWLINE); System.out.println(sb.toString());
        return totT;
    }

    static long stringPlus() {
        final StringBuilder sb = new StringBuilder();
        final long t = System.nanoTime();
        for (int i = 0; i < nbIter; i++) {
            String x = "";
            x += (i % 3 == 0) ? "Fizz" : "";
            x += (i % 5 == 0) ? "Buzz" : "";
            if (x.isEmpty()) { // MODIF
                x += Integer.toString(i);
            }
            sb.append(x);// sb.append(sep);
        }
        final long totT = System.nanoTime() - t;
        System.out.format("stringPlus\t%20d\n", totT);
        // sb.append(EnvPrm.NEWLINE); System.out.println(sb.toString());
        return totT;
    }

    static long withIf() {
        final StringBuilder sb = new StringBuilder();
        final long t = System.nanoTime();
        for (int i = 0; i < nbIter; i++) {
            if (i % 3 == 0) {
                sb.append("Fizz");
                if (i % 5 == 0) {
                    sb.append("Buzz");
                }
            } else if (i % 5 == 0) {
                sb.append("Buzz");
            } else {
                sb.append(i);
            }// sb.append(sep);
        }
        final long totT = System.nanoTime() - t;
        System.out.format("withIf\t\t%20d\n", totT);
        // sb.append(EnvPrm.NEWLINE);System.out.println(sb.toString());
        return totT;
    }

    static long withArray() {
        final String[] lis = {"FizzBuzz", "", "", "Fizz", "", "Buzz", "Fizz",
            "", "", "Fizz", "Buzz", "", "Fizz", "", "",};
        final StringBuilder sb = new StringBuilder();
        final long t = System.nanoTime();
        for (int i = 0; i < nbIter; i++) {
            final String pos = lis[i % 15];
            sb.append(((0 == pos.length()) ? i : pos));// sb.append(sep);
        }
        final long totT = System.nanoTime() - t;
        System.out.format("withArray\t%20d\n", totT);
        // sb.append(EnvPrm.NEWLINE); System.out.println(sb.toString());
        return totT;
    }

    static long withTable() {
        final Hashtable<Integer, String> ht = new Hashtable<>(8);
        ht.put(0, "FizzBuzz");
        ht.put(3, "Fizz");
        ht.put(5, "Buzz");
        ht.put(6, "Fizz");
        ht.put(9, "Fizz");
        ht.put(10, "Buzz");
        ht.put(12, "Buzz");
        final StringBuilder sb = new StringBuilder();
        final long t = System.nanoTime();
        for (int i = 0; i < nbIter; i++) {
            final String s = ht.get(i % 15);
            // MODIF
            // http://www.developpez.net/forums/d1196563-2/java/general-java/if-null-object-if-objet-null/#post6561766
            // sb.append((null == s ? i : s));// sb.append(sep);
            if (null == s) {
                sb.append(i);
            } else {
                sb.append(s);
            }
        }
        final long totT = System.nanoTime() - t;
        System.out.format("withTable\t%20d\n", totT);
        // sb.append(EnvPrm.NEWLINE); System.out.println(sb.toString());
        return totT;

    }

    static int recursive(final StringBuilder sb, final int n) {
        if (0 == n) {
            return 1;
        }
        if (n % 3 == 0) {
            sb.insert(0, "Fizz");
            if (n % 5 == 0) {
                sb.insert(0, "Buzz");
            }
        } else if (n % 5 == 0) {
            sb.insert(0, "Buzz");
        } else {
            sb.insert(0, n);
        }
        return n + recursive(sb, n - 1);
    }

    static long recursive() {
        final StringBuilder sb = new StringBuilder("");
        final long t = System.nanoTime();
        recursive(sb, nbIter);
        final long totT = System.nanoTime() - t;
        System.out.format("recursive\t%20d\n", totT);
        sb.append(EnvPrm.NEWLINE);
        System.out.println(sb.toString());
        return totT;
    }

    /*** @param args */
    public static void main(final String[] args) {
        long cum = 0L, cum2 = 0L;
        for (int i = 0; i < 5; i++) {
            System.out.println("------ " + i + " -----");
            final long totSb = stringPlus();
            final long totIn = ifNested();
            final long totWi = withIf();
            final long totWa = withArray();
            final long totWt = withTable();
            final long totRe = recursive();
            System.out.format("... stringPlus/withIf :%5d\n", (totSb * 100)
                / totWi);
            System.out.format("...   ifNested/withIf :%5d\n", (totIn * 100)
                / totWi);
            System.out.format("...  withArray/withIf :%5d\n", (totWa * 100)
                / totWi);
            System.out.format("...  withTable/withIf :%5d\n", (totWt * 100)
                / totWi);
            System.out.format("...  recursive/withIf :%5d\n", (totRe * 100)
                / totWi);
            cum += totIn + totSb + totWi + totWa + totWt + totRe;
            System.out.println("CUMUL (SECOND) == " + cum / 100000000 + "."
                + cum % 100000000 + "\t , diff: " + (cum - cum2));
            cum2 = cum;
        }
    }
}

And the output :

------ 0 -----
stringPlus                529397
ifNested                  643657
withIf                     27657
withArray                  43581
withTable                  40788
recursive                  87441
12Fizz4BuzzFizz78FizzBuzz11Fizz1314BuzzFizz1617Fizz19BuzzFizz2223FizzBuzz26Fizz2829BuzzFizz

... stringPlus/withIf : 1914
...   ifNested/withIf : 2327
...  withArray/withIf :  157
...  withTable/withIf :  147
...  recursive/withIf :  316
CUMUL (SECOND) == 0.1372521  , diff: 1372521
------ 1 -----
stringPlus                345295
ifNested                   88280
withIf                     88279
withArray                  88838
withTable                 101689
recursive                  93308
12Fizz4BuzzFizz78FizzBuzz11Fizz1314BuzzFizz1617Fizz19BuzzFizz2223FizzBuzz26Fizz2829BuzzFizz

... stringPlus/withIf :  391
...   ifNested/withIf :  100
...  withArray/withIf :  100
...  withTable/withIf :  115
...  recursive/withIf :  105
CUMUL (SECOND) == 0.2178210  , diff: 805689
------ 2 -----
stringPlus                380216
ifNested                   36597
withIf                     20953
withArray                  60063
withTable                  91352
recursive                 111467
12Fizz4BuzzFizz78FizzBuzz11Fizz1314BuzzFizz1617Fizz19BuzzFizz2223FizzBuzz26Fizz2829BuzzFizz

... stringPlus/withIf : 1814
...   ifNested/withIf :  174
...  withArray/withIf :  286
...  withTable/withIf :  435
...  recursive/withIf :  531
CUMUL (SECOND) == 0.2878858  , diff: 700648
------ 3 -----
stringPlus                489168
ifNested                   29613
withIf                     22070
withArray                  27099
withTable                  27378
recursive                  91911
12Fizz4BuzzFizz78FizzBuzz11Fizz1314BuzzFizz1617Fizz19BuzzFizz2223FizzBuzz26Fizz2829BuzzFizz

... stringPlus/withIf : 2216
...   ifNested/withIf :  134
...  withArray/withIf :  122
...  withTable/withIf :  124
...  recursive/withIf :  416
CUMUL (SECOND) == 0.3566097  , diff: 687239
------ 4 -----
stringPlus                143035
ifNested                   24025
withIf                     15924
withArray                  23187
withTable                  26819
recursive                  87162
12Fizz4BuzzFizz78FizzBuzz11Fizz1314BuzzFizz1617Fizz19BuzzFizz2223FizzBuzz26Fizz2829BuzzFizz

... stringPlus/withIf :  898
...   ifNested/withIf :  150
...  withArray/withIf :  145
...  withTable/withIf :  168
...  recursive/withIf :  547
CUMUL (SECOND) == 0.3886249  , diff: 320152

Answer 4

Here's a version that's (IMHO) a little better for humans than yours and better for computers as well:

public class FizzBuzz {
    public static void main(String[] args) {
        for (int i = 1; i <= 100; i++) {
            String value;
            switch (i % 15) {
            case  3:
            case  6:
            case  9:
            case 12:  // divisible by 3, print Fizz
                value = "Fizz";
                break;
            case  5:
            case 10:  // divisible by 5, print Buzz
                value = "Buzz";
                break;
            case  0:  // divisible by 3 and by 5, print FizzBuzz
                value = "FizzBuzz";
                break;
            default:  // else print the number
                value = Integer.toString(i);
            }
            System.out.println(value);
        }
    }
}

The comments provide information to humans (but they could still see it on their own) and there's only one System.out.println call per i.

EDIT: This is another way to fizz-buzz (focus: DRY):

public class FizzBuzz {
    public static void main(String[] args) {
        final String EMPTY = "";
        for (int i = 1; i <= 100; i++) {
            String value = EMPTY;
            if (i % 3 == 0) value += "Fizz";
            if (i % 5 == 0) value += "Buzz";
            if (value == EMPTY) value += i;
            System.out.println(value);
        }
    }
}

EDIT 2: yet another, using StringBuilder, DRY as well:

public class FizzBuzz {
    public static void main(String[] args) {
        StringBuilder builder = new StringBuilder(1000);
        for (int i = 1; i <= 100; i++) {
            final int length = builder.length();
            if (i % 3 == 0) builder.append("Fizz");
            if (i % 5 == 0) builder.append("Buzz");
            if (length == builder.length()) builder.append(i);
            builder.append('\n');
        }
        System.out.println(builder);
    }
}