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Java Challengers #7: Debugging Java inheritance | JavaWorld https://www.javaworld.com/article/3409071/java-challenger-7-debugging...
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Java Inheritance and Composition: Debugging Examples, Lecture notes of Java Programming
Java code examples and explanations for debugging inheritance and composition in java. It covers topics such as superclass and subclass relationships, method overriding, constructor invocation, and casting. Students can use this document as study notes, lecture notes, summaries, or cheat sheets to understand the concepts of java inheritance and composition.
Typology: Lecture notes
2018/2019
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super
Car Vehicle
class Vehicle { String brand; String color; double weight; double speed; void move() { System.out.println("The vehicle is moving"); } } public class Car extends Vehicle { String licensePlateNumber; String owner; String bodyStyle; public static void main(String... inheritanceExample) { System.out.println(new Vehicle().brand); System.out.println(new Car().brand); new Car().move(); } }
Bedroom LivingRoom House
import java.util.HashSet; public class CharacterBadExampleInheritance extends HashSet
CharacterCompositionExample
HashSet
class IndexOutOfBoundsException extends RuntimeException {...} class ArrayIndexOutOfBoundsException extends IndexOutOfBoundsException {...} class FileWriter extends OutputStreamWriter {...} class OutputStreamWriter extends Writer {...} interface Stream
IndexOutOfBoundsException RuntimeException
Cat
class Animal {} class Mammal {} class Dog extends Animal, Mammal {} class Animal {} class Mammal extends Animal {} class Dog extends Mammal {} interface Animal {} interface Mammal {} class Dog implements Animal, Mammal {}
super
public class SuperWordExample { class Character { Character() { System.out.println("A Character has been created"); } void move() { System.out.println("Character walking..."); } } class Moe extends Character { Moe() { super(); } void giveBeer() { super.move(); System.out.println("Give beer"); } } }
Character super
Character move()
super
super
public class CustomizedConstructorSuper { class Character { Character(String name) { System.out.println(name + "was invoked"); } } class Barney extends Character { // We will have compilation error if we don't invoke the constructor explicitly // We need to add it Barney() { super("Barney Gumble"); } } }
ClassCastException
public class CastingExample { public static void main(String... castingExample) { Animal animal = new Animal(); Dog dogAnimal = (Dog) animal; // We will get ClassCastException Dog dog = new Dog(); Animal dogWithAnimalType = new Dog(); Dog specificDog = (Dog) dogWithAnimalType; specificDog.bark(); Animal anotherDog = dog; // It's fine here, no need for casting System.out.println(((Dog)anotherDog)); // This is another way to cast the object } } class Animal { } class Dog extends Animal { void bark() { System.out.println("Au au"); } }
Animal Dog
Animal
Animal
Animal animal = new Animal(); Dog dogAnimal = (Dog) animal;
Dog Animal Dog
ClassCastException
Dog
Dog dog = new Dog();