lab8 finished

lab/lab8/Question8/Square.java

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+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-14
+ * Description: Square class inherited from Rectangle class
+ */
+
+public class Square extends Rectangle {
+	/**
+	 * Constructor.
+	 *
+	 * @param x    the x coordinate center of the square
+	 * @param y    the y coordinate center of the square
+	 * @param size the size of the square
+	 */
+	public Square(double x, double y, double size) {
+		super(x, y, size, size);
+	}
+
+	/**
+	 * Override the resize(double double) method check width == height.
+	 *
+	 * @param width  the new width of the square
+	 * @param length the new length of the square
+	 */
+	@Override
+	public void resize(double width, double length) throws CannotResizeException {
+		if (width != length) {
+			throw new CannotResizeException("Cannot resize a square into a rectangle!");
+		}
+		super.resize(width, length);
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testSquare() {
+		Square s = new Square(1.2, 3.4, 5.0);
+		// getX, getY, and move are inherited from Shape.
+		// area and resize are inherited from Rectangle.
+		System.out.println(s.getX() == 1.2);
+		System.out.println(s.getY() == 3.4);
+		System.out.println(s.area() == 25.0);
+		// Move the square. The area does not change.
+		s.move(7.8, 9.0);
+		System.out.println(s.getX() == 9.0);
+		System.out.println(s.getY() == 12.4);
+		System.out.println(s.area() == 25.0);
+		// Resize the square. The area changes but not the position.
+		s.resize(12.0);
+		System.out.println(s.getX() == 9.0);
+		System.out.println(s.getY() == 12.4);
+		System.out.println(s.area() == 144.0);
+
+		// Resize the square again with different width and length!
+		// Now the square is not square anymore!
+
+		try {
+			s.resize(10.0, 15.0);
+			System.out.println(s.getX() == 9.0); // Unreachable.
+			System.out.println(s.getY() == 12.4);
+			System.out.println(s.area() == 150.0);
+		} catch (CannotResizeException ex) {
+			System.out.println(ex.getMessage() == "Cannot resize a square into a rectangle!");
+		}
+		// The area and position do not change.
+		System.out.println(s.getX() == 9.0);
+		System.out.println(s.getY() == 12.4);
+		System.out.println(s.area() == 144.0);
+		// Resize the square again with equal width and length.
+		// The area changes but not the position.
+		try {
+			s.resize(10.0, 10.0);
+		} catch (CannotResizeException ex) {
+			System.out.println("BUG! This must never happen!");
+		}
+		System.out.println(s.getX() == 9.0);
+		System.out.println(s.getY() == 12.4);
+		System.out.println(s.area() == 100.0);
+
+	}
+}