Tag: programming languages

The following code contains a compilation error , what can be done to fix this error – independently?

abstract class AirPlane 
{ // line 1  
    abstract void fly(); // line 2  
    void land()
    {
        System.out.print("Landing..");
    }
}
class AirJet extends AirPlane 
{ // line 10  
    AirJet()
    {
        super(); // line 13  
    }
    void fly() 
    {
        System.out.print("Flying..");
    }
    abstract void land(); // line 20 
}

Please choose all the answers that apply:
a) Remove abstract from line 20 and add body to method land()

b) Declare class AirJet as abstract to at line 10

c) Remove super() call at line 13

d) Remove abstract at line 1 and line 2

What are the rules to implement an interface? Considering the following declaration for interface Convertable, which of the following code segments will compile?

public interface Convertable {
    int convertToInt();
    char convertToChar();
}

a)

class Digit implements Convertable {
    public char convertToChar() {
        return 0;
    }
    public int convertToInt() {
        return 0;
    }
}

b)

 abstract class Digit implements Convertable {
     int convertToInt();
     char convertToChar();
 }

c)

abstract class Digit implements Convertable {
    public int convertToInt() {
        return 0;
    }
}

d)

abstract class Digit implements Convertable {
    public int convertToInt() {
        return 0;
    }
    char convertToChar();
}

e)

  class Digit implements Convertable {
    int convertToInt() {
        return 0;
        return 0;
    }
}

f)

interface Roundable extends Convertable {
    int roundUp();
}

What is the result of the following code? 1. public class Drink { 2. private int millis = 200; 3. boolean carbonated = false; 4. 5. public static void main(String [] args) { 6. System.out.println(new AppyFizz()); 7. } 8. } 9. class AppyFizz extends Drink { 10. public String toString() { 11. return millis + " " + carbonated; 12. } 13. }

What is the result of the following code? 1. public abstract class A { 2. private void doStuff() { 3. System.out.println("A"); 4. } 5. 6. public static void main(String [] args) { 7. A a = new B(); 8. a.doStuff(); 9. } 10. } 11. 12. class B extends A { 13. protected void doStuff() { 14. System.out.println("B"); 15. } 16. }

What is the result of the following code? 1. public abstract class Catchable { 2. protected abstract void catchAnObject(Object x); 3. 4. public static void main(String [] args) { 5. java.util.Date now = new java.util.Date(); 6. Catchable target = new MyStringCatcher(); 7. target.catchAnObject(now); 8. } 9. } 10. 11. class MyStringCatcher extends Catchable { 12. public void catchAnObject(Object x) { 13. System.out.println("Caught object"); 14. } 15. 16. public void catchAnObject(String s) { 17. System.out.println("Caught string"); 18. } 19. }