JAVA Interfaces and Abstract Classes Runnable is a _____ . class abstract class vaiable method interface class abstract class vaiable method interface ANSWER DOWNLOAD EXAMIANS APP
JAVA Interfaces and Abstract Classes In Java, declaring a class abstract is useful 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. 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. 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 2 3 and 4 2 and 3 1 and 3 2 and 4 1 and 2 3 and 4 2 and 3 1 and 3 ANSWER DOWNLOAD EXAMIANS APP
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. 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. 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 A followed by b is an instance of b is an instance of Nothing. b is an instance of b is an instance of A followed by b is an instance of b is an instance of Nothing. b is an instance of 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? You must add a return statement in method numberOfStudent(). The keywords public and abstract cannot be used together. Class School must be defined abstract. The method numberOfStudent() in class School must have a body. You must add a return statement in method numberOfStudent(). The keywords public and abstract cannot be used together. Class School must be defined abstract. The method numberOfStudent() in class School must have a body. ANSWER DOWNLOAD EXAMIANS APP
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