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"); }}

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

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JAVA Interfaces and Abstract Classes
Given the following piece of code:public interface Guard{ void doYourJob();}abstract public class Dog implements Guard{ }which of the following statements is correct?

This code will not compile, because class Dog must implement method doYourJob() from interface Guard.
This code will not compile, because in the declaration of class Dog we must use the keyword extends instead of implements.
This code will compile without any errors.
This code will not compile, because method doYourJob() in interface Guard must be defined abstract.

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JAVA Interfaces and Abstract Classes
What will be the output?interface A{public void method();}class One{public void method(){System.out.println("Class One method");}}class Two extends One implements A{public void method(){System.out.println("Class Two method");}}public class Test extends Two{public static void main(String[] args){A a = new Two();a.method();}}

compiles fine but print nothing
Compilation Error
None of these
will print Class One method
will print Class Two method

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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(); }}

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

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

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

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