JAVA Interfaces and Abstract Classes
What will be the output for the below code ?public interface TestInf{ int i =10;}public class Test{ public static void main(String... args){ TestInf.i=12; System.out.println(TestInf.i); }}

None of these
12
Compile with error
Runtime Exception
10

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

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

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

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

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

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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(); }}

None of these
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.
The code will lead to a compilation error as the display method is not declared as abstract.

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