Domino.java

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1/* 2 * Domino.java3 * 4 * Computer Science S-225 */6 7/**8 * A class representing a domino tile9 * 10 * For example, the 5-2 domino looks like this:11 * 12 *   ╭───────────┬───────────╮13 *   │  ●     ●  │   ●       │14 *   │     ●     │           │15 *   │  ●     ●  │        ●  │16 *   ╰───────────┴───────────╯17 *18 * Instances of this class are immutable. To obtain the flipped version of19 * a domino, use the return value of the flipped() method. The equals() method20 * returns true when both sides of two dominoes are the same, flipped or not.21 */22public class Domino {23    private final int left;24    private final int right;25 26    public Domino(int left, int right) {27        if (left < 0 || right < 0) {28            throw new IllegalArgumentException("must have positive # of dots");29        }30        if (left > 6 || right > 6) {31            throw new IllegalArgumentException("# of dots must be 6 or less");32        }33        this.left = left;34        this.right = right;35    }36 37    /**38     * Return the left side of this domino.39     */40    public int getLeft() {41        return this.left;42    }43 44    /**45     * Return the right side of this domino.46     */47    public int getRight() {48        return this.right;49    }50 51    /**52     * Return a flipped version of this domino.53     */54    public Domino flipped() {55        return new Domino(this.right, this.left);56    }57 58    /**59     * Return true if the domino is a "double" (same value on both sides).60     */61    public boolean isDouble() {62        return this.right == this.left;63    }64 65    /**66     * Two dominoes are equal when they have the same sides, flipped or not.67     */68    @Override69    public boolean equals(Object otherObj) {70        if (!(otherObj instanceof Domino)) {71            return false;72        }73 74        Domino other = (Domino)otherObj;75        return this.left == other.left && this.right == other.right ||76               this.left == other.right && this.right == other.left;77    }78 79    @Override80    public String toString() {81        return String.format("%d-%d", this.left, this.right);82    }83 84    public static void main(String[] args) {85        Domino oneFour = new Domino(1, 4);86        Domino fourOne = oneFour.flipped();     // i.e., new Domino(4, 1)87 88        System.out.println("1-4 equals 4-1? " + oneFour.equals(fourOne));89 90        // Two different objects in memory, so == gives us false91        System.out.println("1-4 == 4-1? " + (oneFour == fourOne));92    }93}