What is inheritance?

basically being able to reuse code over and over, defining functions that will be used for all child classes

  • each type of the parent c lass will extend, inheriting the base class

SuperClass/SubClass

  • protected keyword to keep attiribute from being affected by outside modifiers
  • can add own attribute or customize an attribute in the subclass
    • can call superclass constructor first

HACK 1 

public class Animal {
    private String name;
    private int numLegs;
    
    public Animal(String name, int numLegs) {
        this.name = name;
        this.numLegs = numLegs;
    }
    
    public String getName() {
        return this.name;
    }
    
    public int getNumLegs() {
        return this.numLegs;
    }
}
    
public class Mammal extends Animal {
    private boolean hasFur;
    
    public Mammal(String name, int numLegs, boolean hasFur) {
        super(name, numLegs);
        this.hasFur = hasFur;
    }
    
    public boolean hasFur() {
        return this.hasFur;
    }
}

Overriding

  • allows child class to override specific implementation of method in superclass
public class Animal {
    private String name;
    private int numLegs;
    
    public Animal(String name, int numLegs) {
        this.name = name;
        this.numLegs = numLegs;
    }
    
    public String getName() {
        return this.name;
    }
    
    public int getNumLegs() {
        return this.numLegs;
    }

    public void makeNoise() {
        System.out.println("bahahaha");
    }
}
    
public class Mammal extends Animal {
    private boolean hasFur;
    
    public Mammal(String name, int numLegs, boolean hasFur) {
        super(name, numLegs);
        this.hasFur = hasFur;
    }
    
    public boolean hasFur() {
        return this.hasFur;
    }

    @Override
    public void makeNoise() {
        System.out.println("rawr");
    }
}

super ?

  • make constructors and make methods

Polymorphism

  • do one thing many ways, like using overriding
  • also compile time: early bindiong vs late binding (see Unit 5)