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); }}

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

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

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

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JAVA Interfaces and Abstract Classes
Determine output of the following code.interface A { }class C { }class D extends C { }class B extends D implements A { }public class Test extends Thread{ public static void main(String[] args){ B b = new B(); if (b instanceof A) System.out.println("b is an instance of A"); if (b instanceof C) System.out.println("b is an instance of C"); }}

b is an instance of
Nothing.
b is an instance of
b is an instance of A followed by b is an instance of

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