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java-coordinate-playground-exercise-polymorphism/java-coordinate-playground-exercise-polymorphism/settings.gradle

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+rootProject.name = 'java-coordinate-playground'

src/main/java/coordinate/AbstractFigure.java

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+package coordinate;
+
+import java.util.List;
+
+public abstract class AbstractFigure implements Figure {
+    private final List<Point> points;
+
+    public AbstractFigure(List<Point> points) {
+        if (points.size() != size()) {
+            throw new IllegalArgumentException(getName() + "의 길이는 " + size() + "이어야 합니다.");
+        }
+
+        this.points = points;
+    }
+
+    protected Point getPoint(int index) {
+        return points.get(index);
+    }
+
+    @Override
+    public List<Point> getPoints() {
+        return points;
+    }
+}

src/main/java/coordinate/Figure.java

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+package coordinate;
+
+import java.util.List;
+
+public interface Figure {
+    List<Point> getPoints();
+
+    int size();
+
+    String getName();
+
+    double area();
+}

src/main/java/coordinate/FigureCreator.java

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+package coordinate;
+
+import java.util.List;
+
+public interface FigureCreator {
+    Figure create(List<Point> points);
+}

src/main/java/coordinate/FigureFactory.java

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+package coordinate;
+
+import java.util.List;
+
+public class FigureFactory {
+    static Figure getInstance(List<Point> points) {
+        if (points.size() == Line.LINE_POINT_SIZE) {
+            return new Line(points);
+        }
+
+        if (points.size() == Triangle.TRIANGLE_POINT_SIZE) {
+            return new Triangle(points);
+        }
+
+        if (points.size() == Rectangle.RECTANGLE_POINT_SIZE) {
+            return new Rectangle(points);
+        }
+
+        throw new IllegalArgumentException("유효하지 않은 도형입니다.");
+    }
+}

src/main/java/coordinate/Line.java

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+package coordinate;
+
+import java.util.List;
+
+public class Line extends AbstractFigure {
+    public static final int LINE_POINT_SIZE = 2;
+
+    public Line(List<Point> points) {
+        super(points);
+    }
+
+    @Override
+    public int size() {
+        return LINE_POINT_SIZE;
+    }
+
+    @Override
+    public String getName() {
+        return "선";
+    }
+
+    @Override
+    public double area() {
+        return 0;
+    }
+}

src/main/java/coordinate/Point.java

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+package coordinate;
+
+import java.util.Objects;
+
+public class Point {
+    private final int x;
+    private final int y;
+
+    private Point(int x, int y) {
+        this.x = x;
+        if (x < 0 || x > 24) {
+            throw new IllegalArgumentException();
+        }
+
+        this.y = y;
+        if (y < 0 || y > 24) {
+            throw new IllegalArgumentException();
+        }
+    }
+
+    public double getDistance(Point other) {
+        int xDifference = other.minusX(x);
+        int yDifference = other.minusY(y);
+        return Math.sqrt(square(xDifference) + square(yDifference));
+    }
+
+    private int minusX(int number) {
+        return this.x - number;
+    }
+
+    private int minusY(int number) {
+        return this.y - number;
+    }
+
+    private static int square(int number) {
+        return number * number;
+    }
+
+    public static Point of(int x, int y) {
+        return new Point(x, y);
+    }
+
+    public static Point ofCommaSeparator(String text) {
+        String[] values = text.split(",");
+        return new Point(Integer.parseInt(values[0]), Integer.parseInt(values[1]));
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Point point = (Point) o;
+        return x == point.x &&
+                y == point.y;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(x, y);
+    }
+
+    @Override
+    public String toString() {
+        return "Point{" +
+                "x=" + x +
+                ", y=" + y +
+                '}';
+    }
+}

src/main/java/coordinate/Rectangle.java

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+package coordinate;
+
+import java.util.List;
+
+public class Rectangle extends AbstractFigure {
+    public static final int RECTANGLE_POINT_SIZE = 4;
+
+    public Rectangle(List<Point> points) {
+        super(points);
+    }
+
+    @Override
+    public int size() {
+        return RECTANGLE_POINT_SIZE;
+    }
+
+    @Override
+    public String getName() {
+        return "사각형";
+    }
+
+    @Override
+    public double area() {
+        return 0;
+    }
+}

src/main/java/coordinate/Triangle.java

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+package coordinate;
+
+import java.util.List;
+
+public class Triangle extends AbstractFigure {
+    public static final int TRIANGLE_POINT_SIZE = 3;
+
+    public Triangle(List<Point> points) {
+        super(points);
+    }
+
+    @Override
+    public int size() {
+        return TRIANGLE_POINT_SIZE;
+    }
+
+    @Override
+    public String getName() {
+        return "삼각형";
+    }
+
+    @Override
+    public double area() {
+        return 0;
+    }
+}

src/test/FigureFactoryTest.java

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+package coordinate;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class FigureFactoryTest {
+    @Test
+    public void line() {
+        List<Point> points = Arrays.asList(
+                Point.of(1, 2),
+                Point.of(2, 3));
+
+        Figure figure = FigureFactory.getInstance(points);
+        assertThat(figure).isInstanceOfAny(Line.class);
+        assertThat(figure.getName()).isEqualTo("선");
+    }
+
+    @Test
+    public void triangle() {
+        List<Point> points = Arrays.asList(
+                Point.of(1, 1),
+                Point.of(4, 1),
+                Point.of(1, 4));
+
+        Figure figure = FigureFactory.getInstance(points);
+        assertThat(figure).isInstanceOfAny(Triangle.class);
+        assertThat(figure.getName()).isEqualTo("삼각형");
+    }
+
+    @Test
+    public void rectangle() {
+        List<Point> points = Arrays.asList(
+                Point.of(1, 1),
+                Point.of(4, 1),
+                Point.of(1, 4),
+                Point.of(4, 4));
+
+        Figure figure = FigureFactory.getInstance(points);
+        assertThat(figure).isInstanceOfAny(Rectangle.class);
+        assertThat(figure.getName()).isEqualTo("사각형");
+    }
+}