JAVA Interfaces and Abstract Classes
Given the following piece of code:public class School{ public abstract double numberOfStudent();}which of the following statements is true?

You must add a return statement in method numberOfStudent().
The method numberOfStudent() in class School must have a body.
The keywords public and abstract cannot be used together.
Class School must be defined abstract.

ANSWER DOWNLOAD EXAMIANS APP

JAVA Interfaces and Abstract Classes
Which of the following statements regarding abstract classes are true?

An abstract class can be used as a data type.
All of these
A subclass can override a concrete method in a superclass to declare it abstract.
An abstract class can be extended.
A subclass of a non-abstract superclass can be abstract.

ANSWER DOWNLOAD EXAMIANS APP

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

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

ANSWER DOWNLOAD EXAMIANS APP

JAVA Interfaces and Abstract Classes
What will happen after compiling this program code?abstract class MyClass{ //line 1 private int a, b; public void call(int a, int b){ this.a = a; this.b = b; System.out.print(a+b); }}public class Test{ public static void main(String args[]){ MyClass m = new MyClass(); //line 2 m.call(12,25); }}

Compilation error due to line 2
Runtime error
None of these
Compilation error due to line 1
Successful run and print 37

ANSWER DOWNLOAD EXAMIANS APP

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

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