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?

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

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JAVA Interfaces and Abstract Classes
What will be the output when the following program is compiled and executed?abstract class TestAbstract{ String my_name; String myName(){ my_name = "Examveda"; return my_name; } abstract void display();}public class Test extends TestAbstract{ void display(){ String n = myName(); System.out.print("My name is "+ n); } public static void main(String args[]){ Test t = new Test(); t.display(); }}

Program will compile and execute successfully and prints
Compilation error occurs as the abstract class TestAbstract contains a non-abstract method.
Compilation error as class can not be declared as abstract.
None of these
Program compiles but leads to runtime exception.

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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.
An abstract class can be extended.
A subclass of a non-abstract superclass can be abstract.
A subclass can override a concrete method in a superclass to declare it abstract.

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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 due to public modifier while declaring the display method.
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.
None of these
The code will lead to a compilation error as declaration of the display method has been provided in two interface.

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