JAVA Interfaces and Abstract Classes
Which two of the following are legal declarations for abstract classes and interfaces?1. final abstract class Test {}2. public static interface Test {}3. final public class Test {}4. protected abstract class Test {}5. protected interface Test {}6. abstract public class Test {}

1 and 2
3 and 6
2 and 4
3 and 5
5 and 6

ANSWER DOWNLOAD EXAMIANS APP

JAVA Interfaces and Abstract Classes
Which of the following class definitions defines a legal abstract class?

abstract class A { abstract void unfinished(); }
class A { abstract void unfinished() { } }
class A { abstract void unfinished(); }
public class abstract A { abstract void unfinished(); }

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();}}

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

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

ANSWER DOWNLOAD EXAMIANS APP

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

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

ANSWER DOWNLOAD EXAMIANS APP
MORE MCQ ON JAVA Interfaces and Abstract Classes