JAVA Interfaces and Abstract Classes In Java, declaring a class abstract is useful 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. When it doesn't make sense to have objects of that class. To prevent developers from further extending the 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. When it doesn't make sense to have objects of that class. To prevent developers from further extending the class. 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. You must add a return statement in method numberOfStudent(). Class School must be defined abstract. The method numberOfStudent() in class School must have a body. The keywords public and abstract cannot be used together. You must add a return statement in method numberOfStudent(). Class School must be defined abstract. The method numberOfStudent() in class School must have a body. 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(); }} Program will compile and execute successfully and prints Compilation error occurs as the abstract class TestAbstract contains a non-abstract method. None of these Compilation error as class can not be declared as abstract. Program compiles but leads to runtime exception. Program will compile and execute successfully and prints Compilation error occurs as the abstract class TestAbstract contains a non-abstract method. None of these Compilation error as class can not be declared as abstract. Program compiles but leads to runtime exception. 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 3 1 and 2 3 and 4 1 and 3 2 and 4 2 and 3 1 and 2 3 and 4 1 and 3 2 and 4 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 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 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 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 in the declaration of class Dog we must use the keyword extends instead of implements. 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. } Compilation fails due to an error on line 8 null None of these A Compilation fails due to an error on line 3 Compilation fails due to an error on line 8 null None of these A Compilation fails due to an error on line 3 ANSWER DOWNLOAD EXAMIANS APP
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