JAVA Interfaces and Abstract Classes
Which of the following declares an abstract method in an abstract Java class?

public abstract void method();
public abstract void method() {}
public void method() {}
public abstract method();
public void abstract Method();

ANSWER DOWNLOAD EXAMIANS APP

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

ANSWER DOWNLOAD EXAMIANS APP

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(); }}

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
Compilation error as class can not be declared as abstract.

ANSWER DOWNLOAD EXAMIANS APP

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(); }}

None of these
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 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.

ANSWER DOWNLOAD EXAMIANS APP

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. }

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

ANSWER DOWNLOAD EXAMIANS APP
MORE MCQ ON JAVA Interfaces and Abstract Classes