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(); 1 and 2 2 and 4 3 and 4 1 and 3 2 and 3 1 and 2 2 and 4 3 and 4 1 and 3 2 and 3 ANSWER DOWNLOAD EXAMIANS APP
JAVA Interfaces and Abstract Classes Which of the following statements regarding abstract classes are true? An abstract class can be extended. A subclass can override a concrete method in a superclass to declare it abstract. An abstract class can be used as a data type. A subclass of a non-abstract superclass can be abstract. All of these An abstract class can be extended. A subclass can override a concrete method in a superclass to declare it abstract. An abstract class can be used as a data type. A subclass of a non-abstract superclass can be abstract. All of these 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()); }} None of these test-name Compilation succeed but Runtime Exception Compilation fails due to an error on lines 2 Compilation fails due to an error on lines 1 None of these test-name Compilation succeed but Runtime Exception Compilation fails due to an error on lines 2 Compilation fails due to an error on lines 1 ANSWER DOWNLOAD EXAMIANS APP
JAVA Interfaces and Abstract Classes In Java, declaring a class abstract is useful When it makes sense to have objects of that class. To prevent developers from further extending the class. When it doesn't make 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 makes sense to have objects of that class. To prevent developers from further extending the class. When it doesn't make 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. 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(). 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. The keywords public and abstract cannot be used together. ANSWER DOWNLOAD EXAMIANS APP
JAVA Interfaces and Abstract Classes What will happen after compiling this program code?abstract class MyClass{ //line 1 private int a, b; public void call(int a, int b){ this.a = a; this.b = b; System.out.print(a+b); }}public class Test{ public static void main(String args[]){ MyClass m = new MyClass(); //line 2 m.call(12,25); }} Compilation error due to line 1 Successful run and print 37 None of these Compilation error due to line 2 Runtime error Compilation error due to line 1 Successful run and print 37 None of these Compilation error due to line 2 Runtime error ANSWER DOWNLOAD EXAMIANS APP
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