Close: #1 Lab 7

lab/lab7/Question4/Animal.java

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+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022/04/03
+ * Description: This is the abstract animal class.
+ */
+
+public abstract class Animal {
+	/**
+	 * The name for the animal.
+	 */
+	private String name;
+
+	/**
+	 * Constructor
+	 *
+	 * @param String. The name for the animal.
+	 */
+	public Animal(String name) {
+		this.name = name;
+	}
+
+	/**
+	 * Getter for the name.
+	 *
+	 * @return String. The name of the animal.
+	 */
+	public String getName() {
+		return name;
+	}
+
+	/**
+	 * Abstract getLegs methods returns as result the animal's number of legs.
+	 *
+	 * @return int. The number of legs.
+	 */
+	public abstract int getLegs();
+
+	/**
+	 * Abstract canFly methods returns as result the animal's ability to fly.
+	 *
+	 * @return boolean. The ability to fly.
+	 */
+	public abstract boolean canFly();
+
+	/**
+	 * Test.
+	 */
+	public static void testAnimal() {
+		Animal a = new Animal("Animal") {
+			@Override
+			public int getLegs() {
+				return 4;
+			}
+
+			@Override
+			public boolean canFly() {
+				return false;
+			}
+		};
+		System.out.println(a.getName() == "Animal");
+		System.out.println(a.getLegs() == 4);
+		System.out.println(a.canFly() == false);
+	}
+}

lab/lab7/Question4/Bird.java

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+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022/04/03
+ * Description: This is the abstract class of Bird.
+ */
+
+public abstract class Bird extends Animal {
+	/**
+	 * An integer indicate how many eggs the bird has.
+	 */
+	private int numOfEggs;
+
+	/**
+	 * A constructor of Bird.
+	 * 
+	 * @param name      The name of the bird.
+	 * @param numOfEggs The number of eggs the bird has.
+	 */
+	public Bird(String name, int numOfEggs) {
+		super(name);
+		this.numOfEggs = numOfEggs;
+	}
+
+	/**
+	 * Getter of numOfEggs.
+	 *
+	 * @return The number of eggs the bird has.
+	 */
+	public int getNumOfEggs() {
+		return numOfEggs;
+	}
+
+	/**
+	 * Bird have 2 legs.
+	 *
+	 * @return int
+	 */
+	@Override
+	public int getLegs() {
+		return 2;
+	}
+
+	/**
+	 * Abstract method of canFly. Some birds can fly (for example magpies) and some
+	 * birds cannot fly (for example ostriches).
+	 */
+	public abstract boolean canFly();
+
+	/**
+	 * Test.
+	 */
+	public static void testBird() {
+		Bird b1 = new Bird("magpie", 1) {
+			@Override
+			public boolean canFly() {
+				return true;
+			}
+		};
+		System.out.println(b1.getName() == "magpie");
+		System.out.println(b1.getNumOfEggs() == 1);
+		System.out.println(b1.canFly() == true);
+		System.out.println(b1.getLegs() == 2);
+
+		Bird b2 = new Bird("ostriches", 2) {
+			@Override
+			public boolean canFly() {
+				return false;
+			}
+		};
+		System.out.println(b2.getName() == "ostriches");
+		System.out.println(b2.getNumOfEggs() == 2);
+		System.out.println(b2.canFly() == false);
+		System.out.println(b2.getLegs() == 2);
+	}
+}

lab/lab7/Question4/Dog.java

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+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022/04/03
+ * Description: This is the class of Dog. Dog has 4 legs and can not fly.
+ */
+
+public class Dog extends Animal {
+	/**
+	 * Constructor of Dog.
+	 *
+	 * @param name String
+	 */
+	public Dog(String name) {
+		super(name);
+	}
+
+	/**
+	 * Dog has 4 legs.
+	 *
+	 * @return int
+	 */
+	@Override
+	public int getLegs() {
+		return 4;
+	}
+
+	/**
+	 * Dog can not fly.
+	 *
+	 * @return boolean
+	 */
+	@Override
+	public boolean canFly() {
+		return false;
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testDog() {
+		Dog d = new Dog("Jack");
+		System.out.println(d.getName() == "Jack");
+		System.out.println(d.getLegs() == 4);
+		System.out.println(d.canFly() == false);
+	}
+}
+

lab/lab7/Question4/Magpie.java

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+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022/04/03
+ * Description: This is the class of Magpie, which is a child class of Brid.
+ */
+
+public class Magpie extends Bird {
+	/**
+	 * Constructor. Magpie always have 6 eggs.
+	 *
+	 * @param name
+	 */
+	public Magpie(String name) {
+		super(name, 6);
+	}
+
+	/**
+	 * Magpie can fly.
+	 *
+	 * @return true
+	 */
+	@Override
+	public boolean canFly() {
+		return true;
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testMagpie() {
+		Bird bird = new Magpie("Magpie");
+		System.out.println(bird.getName() == "Magpie");
+		System.out.println(bird.getNumOfEggs() == 6);
+		System.out.println(bird.canFly() == true);
+		System.out.println(bird.getLegs() == 2);
+
+	}
+}

lab/lab7/Question4/Start.java

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+/**
+ * Answer to Question.
+ *
+ * Answer to Question 1:
+ *
+ * - Q: Should the getLegs methods be abstract? Why or why not?
+ *
+ * - A: Yes. Because different animal have different number of legs. In animal
+ * class we didn't define how many legs an animal has.
+ *
+ * - Q: Should the canFly methods be abstract? Why or why not?
+ *
+ * - A: Yes. Because different animal have different ability to fly. In animal
+ * class we didn't define how an animal can fly.
+ *
+ * - Q: Should the Animal class be abstract? Why or why not?
+ *
+ * - A: Yes. Because different animal have different properties. In animal class
+ * we didn't define how an animal is.
+ *
+ * - Q: What kinds of test can you write inside the testAnimal method?
+ *
+ * - A: You can write test for the getLegs and canFly methods. Before that, you
+ * need to inherit the Animal class and override the getLegs and canFly methods.
+ * Because the Animal class is abstract, you can't create an object of it.
+ */
+public class Start {
+	public static void main(String[] args) {
+		Animal.testAnimal();
+		Dog.testDog();
+		Bird.testBird();
+		Magpie.testMagpie();
+	}
+}