JAVA Interfaces and Abstract Classes In Java, declaring a class abstract is useful When it doesn't make sense to have objects of that class. When it makes sense to have objects of that class. When default implementations of some methods are not desirable. To force developers to extend the class not to use its capabilities. To prevent developers from further extending the class. When it doesn't make sense to have objects of that class. When it makes sense to have objects of that class. When default implementations of some methods are not desirable. To force developers to extend the class not to use its capabilities. To prevent developers from further extending the class. 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 Which of the following statements regarding abstract classes are true? A subclass can override a concrete method in a superclass to declare it abstract. All of these An abstract class can be extended. A subclass of a non-abstract superclass can be abstract. An abstract class can be used as a data type. A subclass can override a concrete method in a superclass to declare it abstract. All of these An abstract class can be extended. A subclass of a non-abstract superclass can be abstract. An abstract class can be used as a data type. ANSWER DOWNLOAD EXAMIANS APP
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()); }} Compilation fails due to an error on lines 1 test-name Compilation fails due to an error on lines 2 Compilation succeed but Runtime Exception None of these Compilation fails due to an error on lines 1 test-name Compilation fails due to an error on lines 2 Compilation succeed but Runtime Exception None of these 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 method doYourJob() in interface Guard must be defined abstract. This code will compile without any errors. This code will not compile, because in the declaration of class Dog we must use the keyword extends instead of implements. This code will not compile, because class Dog must implement method doYourJob() from interface Guard. This code will not compile, because method doYourJob() in interface Guard must be defined abstract. This code will compile without any errors. This code will not compile, because in the declaration of class Dog we must use the keyword extends instead of implements. This code will not compile, because class Dog must implement method doYourJob() from interface Guard. ANSWER DOWNLOAD EXAMIANS APP
JAVA Interfaces and Abstract Classes Which of the following declares an abstract method in an abstract Java class? public abstract method(); public void abstract Method(); public void method() {} public abstract void method() {} public abstract void method(); public abstract method(); public void abstract Method(); public void method() {} public abstract void method() {} public abstract void method(); ANSWER DOWNLOAD EXAMIANS APP
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