JAVA Interfaces and Abstract Classes In Java, declaring a class abstract is useful When it makes sense to have objects of that class. When it doesn't make sense to have objects of that class. When default implementations of some methods are not desirable. To prevent developers from further extending the class. To force developers to extend the class not to use its capabilities. When it makes sense to have objects of that class. When it doesn't make sense to have objects of that class. When default implementations of some methods are not desirable. To prevent developers from further extending the class. To force developers to extend the class not to use its capabilities. 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 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 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 null None of these Compilation fails due to an error on line 8 Compilation fails due to an error on line 3 A null None of these Compilation fails due to an error on line 8 Compilation fails due to an error on line 3 ANSWER DOWNLOAD EXAMIANS APP
JAVA Interfaces and Abstract Classes Suppose A is an abstract class, B is a concrete subclass of A, and both A and B have a default constructor. Which of the following is correct?1. A a = new A();2. A a = new B();3. B b = new A();4. B b = new B(); 2 and 4 1 and 3 1 and 2 3 and 4 2 and 3 2 and 4 1 and 3 1 and 2 3 and 4 2 and 3 ANSWER DOWNLOAD EXAMIANS APP
JAVA Interfaces and Abstract Classes Given the following piece of code:public class School{ public abstract double numberOfStudent();}which of the following statements is true? The keywords public and abstract cannot be used together. The method numberOfStudent() in class School must have a body. Class School must be defined abstract. You must add a return statement in method numberOfStudent(). The keywords public and abstract cannot be used together. The method numberOfStudent() in class School must have a body. Class School must be defined abstract. You must add a return statement in method numberOfStudent(). ANSWER DOWNLOAD EXAMIANS APP
JAVA Interfaces and Abstract Classes Runnable is a _____ . method interface abstract class class vaiable method interface abstract class class vaiable ANSWER DOWNLOAD EXAMIANS APP
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