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

public abstract void method();
public abstract method();
public void abstract Method();
public void method() {}
public abstract void 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.
Compilation error occurs as the abstract class TestAbstract contains a non-abstract method.
Program compiles but leads to runtime exception.
None of these
Program will compile and execute successfully and prints

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JAVA Interfaces and Abstract Classes
What will be the output?1. public interface InfA{2. protected String getName();3. }public class Test implements InfA{ public String getName(){ return "test-name"; } public static void main (String[] args){ Test t = new Test(); System.out.println(t.getName()); }}

test-name
None of these
Compilation fails due to an error on lines 2
Compilation succeed but Runtime Exception
Compilation fails due to an error on lines 1

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

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

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
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();}}

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

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