Adding extra exercises for Polymorphism and Inheritance

T5Q2-Marcus/T5Q2-Marcus.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

T5Q2-Marcus/src/ClassA.java

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+public class ClassA {
+    public void method1() {
+        System.out.println("ClassA.method1");
+    }
+
+    public void method2() {
+        System.out.println("ClassA.method2");
+    }
+}

T5Q2-Marcus/src/ClassB.java

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+public class ClassB extends ClassA {
+    public void method2() {
+        System.out.println("ClassB.method2");
+    }
+
+    public void method3() {
+        System.out.println("ClassB.method3");
+    }
+}

T5Q2-Marcus/src/ClassC.java

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+public class ClassC extends ClassB {
+    public void method3() {
+        System.out.println("ClassC.method3");
+    }
+
+    public void method4() {
+        System.out.println("ClassC.method4");
+    }
+}

T5Q2-Marcus/src/Main.java

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+public class Main {
+    public static void main(String[] args) {
+        // I
+//        ClassA a = new ClassB();
+//        ClassB b = (ClassB) a;
+//        b.method2(); // ClassB.method2
+//        b.method1(); // ClassA.method1
+
+        // II
+//        ClassA c = new ClassB();
+//        ClassC d = (ClassC) c; // Runtime error here
+//        d.method3(); // Never executed
+
+        // III
+//        ClassA e = new ClassC();
+//        ClassB f = (ClassB) e;
+//        f.method3(); // ClassC.method3
+//        f.method2(); // ClassB.method2
+//        f.method1(); // ClassA.method1
+
+        // IV
+//        ClassC g = (ClassC) new ClassA(); // Runtime error
+//        g.method1(); // never executed
+    }
+}