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

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

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JAVA Interfaces and Abstract Classes
interface Base{ boolean m1 (); byte m2(short s);}which two code fragments will compile?1. interface Base2 implements Base {}2. abstract class Class2 extends Base { public boolean m1(){ return true; }}3. abstract class Class2 implements Base {}4. abstract class Class2 implements Base { public boolean m1(){ return (7 > 4); }}5. abstract class Class2 implements Base { protected boolean m1(){ return (5 > 7) }}

3 and 4
1 and 3
4 and 5
2 and 3
1 and 2

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

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

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