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 will be the output?1. public interface InfA{2. protected String getName();3. }public class Test implements InfA{ public String getName(){ return "test-name"; } public static void main (String[] args){ Test t = new Test(); System.out.println(t.getName()); }}

Compilation succeed but Runtime Exception
test-name
Compilation fails due to an error on lines 1
None of these
Compilation fails due to an error on lines 2

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

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

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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. }

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

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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(); }}

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.
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.
None of these

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

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