JAVA Interfaces and Abstract Classes
Which of the following is a correct interface?

interface A { void print(); }
interface A { void print() { } }
abstract interface A { print(); }
abstract interface A { abstract void print(); { }}

ANSWER DOWNLOAD EXAMIANS APP

JAVA Interfaces and Abstract Classes
What is the output for the below code ?interface A{ public void printValue();}1. public class Test{2. public static void main (String[] args){3. A a1 = new A(){4. public void printValue(){5. System.out.println("A");6. }7. };8. a1.printValue();9. }10. }

A
Compilation fails due to an error on line 3
null
Compilation fails due to an error on line 8
None of these

ANSWER DOWNLOAD EXAMIANS APP

JAVA Interfaces and Abstract Classes
Determine output of the following code.interface A { }class C { }class D extends C { }class B extends D implements A { }public class Test extends Thread{ public static void main(String[] args){ B b = new B(); if (b instanceof A) System.out.println("b is an instance of A"); if (b instanceof C) System.out.println("b is an instance of C"); }}

b is an instance of
b is an instance of A followed by b is an instance of
Nothing.
b is an instance of

ANSWER DOWNLOAD EXAMIANS APP

JAVA Interfaces and Abstract Classes
What will be the output?interface A{public void method();}class One{public void method(){System.out.println("Class One method");}}class Two extends One implements A{public void method(){System.out.println("Class Two method");}}public class Test extends Two{public static void main(String[] args){A a = new Two();a.method();}}

Compilation Error
None of these
compiles fine but print nothing
will print Class Two method
will print Class One method

ANSWER DOWNLOAD EXAMIANS APP

JAVA Interfaces and Abstract Classes
In Java, declaring a class abstract is useful

To force developers to extend the class not to use its capabilities.
When it doesn't make sense to have objects of that class.
To prevent developers from further extending the class.
When it makes sense to have objects of that class.
When default implementations of some methods are not desirable.

ANSWER DOWNLOAD EXAMIANS APP

JAVA Interfaces and Abstract Classes
What happens if the following program is compiled and executed?interface MyInterface{ void display();}interface MySubInterface extends MyInterface{ void display();}public class Test implements MySubInterface{ public void display(){ System.out.print("Welcome to Examveda."); } public static void main(String args[]){ Test t = new Test(); t.display(); }}

The code will lead to a compilation error as declaration of the display method has been provided in two interface.
The code will lead to a compilation error due to public modifier while declaring the display method.
The code will lead to a compilation error as the display method is not declared as abstract.
The code will compile and execute successfully showing the output Welcome to Examians.
None of these

ANSWER DOWNLOAD EXAMIANS APP