Inheritance in Java MCQ

Q 1: Which of these keywords must be used to inherit a class?

A super
B this
C extent
D extends

Q 2: Which of these keywords is used to refer to member of base class from a sub class?

A upper
B super
C this
D none of the mentioned

Q 3: A class member declared protected becomes member of subclass of which type?

A public member
B private member
C protected member
D static member

Q 4: Which of these is correct way of inheriting class A by class B?

A class B + class A {}
B class B inherits class A {}
C class B extends A {}
D class B extends class A {}

Q 5: Which two classes use the Shape class correctly?

  
A. public class Circle implements Shape 
   {
    private int radius;
   }
B. public abstract class Circle extends Shape 
   {
    private int radius;
   }
C. public class Circle extends Shape 
   {
   private int radius;
   public void draw();
   }
D. public abstract class Circle implements Shape 
   {
    private int radius;
    public void draw();
   }
E. public class Circle extends Shape 
   {
    private int radius;
    public void draw()
    {
     /* code here */
    }
   }
F. public abstract class Circle implements Shape 
   {
     private int radius;
     public void draw() 
     { 
      /* code here */ 
     }
   }

A B,E
B A,C
C C,E
D T,H

Q 6: What is the output of this program?

     class A 
    {
        int i;
        void display() 
        {
            System.out.println(i);
        }
    }    
    class B extends A 
    {
        int j;
        void display() 
        {
            System.out.println(j);
        }
    }    
    class inheritance_demo 
    {
        public static void main(String args[])
        {
            B obj = new B();
            obj.i=1;
            obj.j=2;   
            obj.display();     
        }
   }

A 0
B 1
C 2
D Compilation Error

Q 7: What is the output of this program?

     class A 
    {
        int i;
    }    
    class B extends A 
    {
        int j;
        void display() 
        {
            super.i = j + 1;
            System.out.println(j + " " + i);
        }
    }    
    class inheritance 
    {
        public static void main(String args[])
        {
            B obj = new B();
            obj.i=1;
            obj.j=2;   
            obj.display();     
        }
   }

A 2 2
B 3 3
C 2 3
D 3 2

Q 8: What is the output of this program?

      class A 
    {
        public int i;
        private int j;
    }    
    class B extends A 
    {
        void display() 
        {
            super.j = super.i + 1;
            System.out.println(super.i + " " + super.j);
        }
    }    
    class inheritance 
    {
        public static void main(String args[])
        {
            B obj = new B();
            obj.i=1;
            obj.j=2;   
            obj.display();     
        }
   }

A 2 2
B 3 3
C Runtime Error
D Compilation Error

Q 9: What is the output of this program?

    class A 
    {
        public int i;
        public int j;
        A() 
        {
            i = 1;
            j = 2;
	}
    }    
    class B extends A 
    {
        int a;
        B() 
        {
            super();
        } 
    }    
    class super_use 
    {
        public static void main(String args[])
        {
            B obj = new B();
            System.out.println(obj.i + " " + obj.j)     
        }
   }

A 1 2
B 2 1
C Runtime Error
D Compilation Error

Q 10: What is the output of this program?

class A 
    {
        public int i;
        protected int j;
    }    
    class B extends A 
    {
        int j;
        void display() 
        {
            super.j = 3;
            System.out.println(i + " " + j);
        }
    }    
    class Output 
    {
        public static void main(String args[])
        {
            B obj = new B();
            obj.i=1;
            obj.j=2;   
            obj.display();     
        }
   }

A 1 2
B 2 1
C 1 3
D 3 1

Q 11: Which is true?

A "X extends Y" is correct if and only if X is a class and Y is an interface
B "X extends Y" is correct if and only if X is an interface and Y is a class
C "X extends Y" is correct if X and Y are either both classes or both interfaces
D "X extends Y" is correct for all combinations of X and Y being classes and/or interfaces

Q 12: Which of the following is true?
1. A class can extend more than one class.
2. A class can extend only one class but many interfaces.
3. An interface can extend many interfaces.
4. An interface can implement many interfaces.
5. A class can extend one class and implement many interfaces.

A 1 and 2
B 2 and 4
C 3 and 5
D 3 and 4

Q 13: What is the result of compiling and running the following code?

class Base{
        public Base(){
                System.out.print("Base");
        }
}
public class Derived extends Base{
        public Derived(){
                this("Examveda");
                System.out.print("Derived");
        }
        public Derived(String s){
                System.out.print(s);
        }
        public static void main(String[] args){
                new Derived();
        }
}

A ExamvedaDerived
B ExamvedaBaseDerived
C BaseExamvedaDerived
D ExamvedaDerivedBase

Q 14: What is the output of the following program code?

abstract class C1{
	public C1(){ 
		System.out.print(1); 
	} 
} 
class C2 extends C1{ 
	public C2(){ 
		System.out.print(2); 
	} 
} 
class C3 extends C2{ 
	public C3(){ 
		System.out.println(3); 
	} 
} 
public class Test{ 
	public static void main(String[] a){ 
		new C3(); 
	} 
}

A 12
B 23
C 123
D 321

Q 15: The concept of multiple inheritance is implemented in Java by
I. Extending two or more classes.
II. Extending one class and implementing one or more interfaces.
III. Implementing two or more interfaces.

A Only (II)
B (I) and (II)
C (II) and (III)
D Only (I)

Q 16: What will be the output?

interface A{
	public void method1();
}
class One implements A{
	public void method1(){
		System.out.println("Class One method1");
	}
}
class Two extends One{
	public void method1(){
		System.out.println("Class Two method1");
	}
}
public class Test extends Two{
	public static void main(String[] args){
		A a = new Two();
		a.method1();
	}
}

A Compilation Error
B Class One method1
C Class One method1
D Throws a NoSuchMethodException at runtime.

Q 17: What is the result of compiling and running this program?

class Mammal{
      void eat(Mammal m){
            System.out.println("Mammal eats food");
      }
}
class Cattle extends Mammal{
      void eat(Cattle c){
            System.out.println("Cattle eats hay");
      }
}
class Horse extends Cattle{
      void eat(Horse h){
            System.out.println("Horse eats hay");
      }
}
public class Test{
      public static void main(String[] args){
            Mammal h = new Horse();
            Cattle c = new Horse();
            c.eat(h);
      }
}

A prints "Mammal eats food"
B prints "Cattle eats hay"
C prints "Horse eats hay"
D Class cast Exception at runtime.

Q 18: Determine output:

class A{
	public void method1(){
		System.out.print("Class A method1");
	}
}
class B extends A{
	public void method2(){
		System.out.print("Class B method2");
	}
}
class C extends B{
	public void method2(){
		System.out.print("Class C method2");
	}	
	public void method3(){
		System.out.print("Class C method3");
	}
}
public class Test{
	public static void main(String args[]){
		A a = new A();
		C c = new C();		
		c.method2();
		a = c;
		a.method3();
	}
}

A Class B method2 Class C method3
B Class C method2 Class C method3
C Compilation Error
D Runtime exception

Q 19: What will be printed after executing following program code?

class Base{
	int value = 0;
        Base(){
        	addValue();
        }
        void addValue(){
        	value += 10;
        }
        int getValue(){
        	return value;
        }
}
class Derived extends Base{
	Derived(){
		addValue();
	}
	void addValue(){
		value +=  20;
	}
}
public class Test{
	public static void main(String[] args){
		Base b = new Derived();
		System.out.println(b.getValue());
	}
}

A 30
B 10
C 40
D None of these

Q 20: What will be the output?

class Parent{
      public void method(){
            System.out.println("Hi i am parent");
      }
}
public class Child extends Parent{
      protected void method(){
            System.out.println("Hi i am Child");
      }
      public static void main(String args[]){
            Child child = new Child();
            child.method();
      }
}

A Compiles successfully and print
B Compiles successfully and print
C Compile time error
D Run Time error

Q 21: What will be the output?

class One{
      final int a = 15;
}

class Two extends One{
      final int a = 20;
}

public class Test extends Two{
      final int a = 30;

      public static void main(String args[]){
            Test t = new One();
            System.out.print(t.a);
      }
}

A 15
B 20
C 30
D Compiler Error

Q 22: What will be the output?

class A{
      int i = 10;
      public void printValue(){
            System.out.print("Value-A");
      }
}

class B extends A{
      int i = 12;
      public void printValue(){
            System.out.print("Value-B");
      }
}

public class Test{
      public static void main(String args[]){
            A a = new B();
            a.printValue();
            System.out.print(a.i);
      }
}

A Value-B 11
B Value-B 10
C Value-A 10
D Value-A 11

Q 23: What will be the result after compiling this code?

class SuperClass{
      public int doIt(String str, Integer... data)throws Exception{
            String signature = "(String, Integer[])";
            System.out.println(str + " " + signature);
            return 1;
      }
}

public class Test extends SuperClass{
      public int doIt(String str, Integer... data){
            String signature = "(String, Integer[])";
            System.out.println("Overridden: " + str + " " +signature);
            return 0;
      }

      public static void main(String... args){
            SuperClass sb = new Test();
            sb.doIt("hello", 3);
      }
}

A Overridden: hello (String, Integer[])
B hello (String, Integer[])
C Compilation fails
D None of these

Q 24:

class A{
      A(String s){}

      A(){}
}

1. class B extends A{
2.       B(){}
3.       B(String s){
4.             super(s);
5.       }
6.       void test(){
7.             // insert code here
8.       }
9. }

Which of the below code can be insert at line 7 to make clean compilation ?

A A a = new B();
B A a = new B(5);
C A a = new A(String s);
D All of the above

Q 25: Determine output:

class A{
      public void printValue(){
            System.out.println("Value-A");
      }
}
class B extends A{
      public void printNameB(){
            System.out.println("Name-B");
      }
}
class C extends A{
      public void printNameC(){
            System.out.println("Name-C");
      }
}

1. public class Test{
2.       public static void main (String[] args){
3.             B b = new B();
4.             C c = new C();
5.             newPrint(b);
6.             newPrint(c);
7.       }
8.       public static void newPrint(A a){
9.             a.printValue();
10.      }
11. }

A Value-A Name-B
B Value-A Value-A
C Value-A Name-C
D Name-B Name-C

Q 26: Determine output:

class A{
      public void printName(){
            System.out.println("Name-A");
      }
}
class B extends A{
      public void printName(){
            System.out.println("Name-B");
      }
}
class C extends A{
      public void printName(){
            System.out.println("Name-C");
      }
}

1. public class Test{
2.       public static void main (String[] args){
3.             B b = new B();
4.             C c = new C();
5.             b = c;
6.             newPrint(b);
7.       }
8.       public static void newPrint(A a){
9.             a.printName();
10.      }
11. }

A Name B
B Name C
C Compilation fails due to an error on lines 5
D Compilation fails due to an error on lines 9

Q 27: What is the output for the below code ?

class A{
      private void printName(){
            System.out.println("Value-A");
      }
}
class B extends A{
      public void printName(){
            System.out.println("Name-B");
      }
}
public class Test{
      public static void main (String[] args){
            B b = new B();
            b.printName();
      }
}

A Value-A
B Name-B
C Value-A Name-B
D Compilation fails - private methods can't be override

Q 28: What will be the result of compiling and running the given code?

class A{
      int b=10;
      private A(){
            this.b=7;
      }
      int f(){
            return b;
      }
}
class B extends A{
      int b;
}
public class Test{
      public static void main(String[] args){
            A a = new B();
            System.out.println(a.f());
      }
}

A Compilation Fails
B Prints 0
C Prints 10
D Prints 7

Q 29: What will be the result of compiling and executing the following program code?

class Vehicle{
      public void printSound(){
            System.out.print("vehicle");
      }
}
class Car extends Vehicle{
      public void printSound(){
            System.out.print("car");
      }
}
class Bike extends Vehicle{
      public void printSound(){
            System.out.print("bike");
      }
}
public class Test{
      public static void main(String[] args){
            Vehicle v = new Car();
            Bike b = (Bike) v;
        
            v.printSound();
            b.printSound();
      }
}

A Compilation fails.
B ClassCastException exception is thrown at runtime.
C "vehiclecar" is printed.
D "vehiclebike" is printed.

Q 30: Determine output:

class Small{
      public Small(){
            System.out.print("a ");
      }
}
class Small2  extends Small{
      public Small2(){
            System.out.print("b ");
      }
}
class Small3 extends Small2{
      public Small3(){
            System.out.print("c ");
      }
}
public class Test{     
      public static void main(String args[]){
            new Small3();
      }
}

A a
B c
C a b c
D c b a

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