Combining class inheritance and interfaces

We can combine class inheritance with the implementation of interfaces. The following lines show the code for a new HideableWonderCat class that inherits from the WonderCat class and implements the Hideable interface. Note that the class declaration includes the superclass (WonderCat) after the extends keyword and the implemented interface (Hideable) after the implements keyword. The code file for the sample is included in the java_9_oop_chapter_08_01 folder, in the example08_07.java file.

public class HideableWonderCat extends WonderCat implements Hideable {
    protected final int numberOfEyes;

    public HideableWonderCat(String nickName, int age, 
        String fullName, int score, 
        int x, int y, int numberOfEyes) {
        super(nickName, age, fullName, score, x, y);
        this.numberOfEyes = numberOfEyes;
    }

    @Override
    public int getNumberOfEyes() {
        return numberOfEyes;
    }

    @Override
    public void show...