Inheritance and Related Concepts

This Test will cover the basic concepts of Inheritance, including Super class, Sub class, their relation. Method Overloading and Overriding also.

Q. Which is true?
Q. Which is not a valid statement based on given code?
class A{}
class B extends A{}
Q. What can be said about the statement y = (Sub) x, based on given code?
// Class declarations :
class Super {}
class Sub extends Super {}
 
// Reference declarations :
Super x;
Sub y;
Q. Which letters will be printed when the given program is run?
public class MyClass 
{
  public static void main(String[] args) 
  {
   B b = new C();
   A a = b;
   if (a instanceof A) System.out.println("A");
   if (a instanceof B) System.out.println("B");
   if (a instanceof C) System.out.println("C");
   if (a instanceof D) System.out.println("D");
  }
}
 
class A {}
class B extends A {}
class C extends B {}
class D extends C {}
Q. Based on the code which of the following statement is correct.
class A
{
  B b;
}
class B{}
Q. What will be the Output?
class Animal
{
  String name = "animal";
  String makeNoise()  { return "generic noise"; }
}
class Dog extends Animal 
{
  String name = "dog";
  String makeNoise() {  return "bark"; }
}
public class Test 
{
  public static void main(String[] args)
  { 
   Animal an = new Dog();
   System.out.println(an.name+" "+an.makeNoise());
  }
}
Q. super keyword in Java is used for?
Q. Which statement is not correct about an overriden method?
public class Test { }
Q. What will be the Output?
class A
{
  public void m1()
  { System.out.println("A"); }
}
public class B extends A
{
  void m1()
  { System.out.println("B"); }
 
 public static void main(String []args)
 {
   A a = new B();
   a.m1();
 }
}
Q. Which operator is used to check object-type at runtime?
Q. Argument passed to a program at the run time is stored in __________.
Q. Predict Output, if the below code is run with given command?

Command Line : java myprog good morning everyone

public class myprog
{ 
   public static void main(String argv[])
   { 
     System.out.println(argv[1]) 
   }
}
Q. Parent class reference variable refers to Child class object, it is known as?
Q. Multiple inheritance is not supported in Java because?

SUBMIT TEST