Quiz J2-2

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Question 1

Consider the classes Letter and A below.

abstract class Letter {
    protected boolean uppercase;

    abstract String get_name();

    abstract int get_alphabet_position();
}

class A extends Letter{
    public String toString() {
        return "A";
    }

    protected int get_alphabet_position() {
        return 1;
    }

    private String get_name() {
        return "A";
    }
}

What is the output of this program?

public class Main{
    public static void main(final String args[]) {
        A a = new A();
        System.out.println("A: " + a.get_alphabet_position());
    }
}

Question 2

What is the output of the program above if A is implemented as shown below

class A extends Letter{
    public String toString() {
        return "A";
    }

    public int get_alphabet_position() {
        return 1;
    }

    protected String get_name() {
        return "A";
    }
}

Question 3

Assume that A is implemented such that the following program will compile and run. What is the output of the below program?

public class tmp{
    public static void foo(A a){
        System.out.println("foo1: "+a.get_name());
    }
    public static void foo(Letter a) {
        System.out.println("foo2: " + a.get_name());
    }
    public static void main(final String args[]) {
        Letter a =(Letter) new A();
        foo(a);
    }
}

Question 4

Consider the Dog class below with an inner class Breed:

public class Dog{

    private String name;
  
    public class Breed{
        private String bname;
        public Breed(String b){this.bname=b;};
        public String toString(){return name+":"+bname;}
    }
    
    public Dog(String n){this.name=n;}

What is the output of the following code snippet?

public static void main(String args[]){
        Dog d1 = new Dog("Jack");
        Dog d2 = new Dog("Champ");

        Dog.Breed b1 = d1.new Breed("pitbull");
        Dog.Breed b2 = d1.new Breed("blacklab");

        System.out.println(b1 + " " + b2);
    }