JAVA Interfaces and Abstract Classes Which of the following statements regarding abstract classes are true? An abstract class can be used as a data type. All of these A subclass of a non-abstract superclass can be abstract. 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. All of these A subclass of a non-abstract superclass can be abstract. An abstract class can be extended. A subclass can override a concrete method in a superclass to declare it 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 b is an instance of Nothing. b is an instance of A followed by b is an instance of b is an instance of b is an instance of Nothing. ANSWER DOWNLOAD EXAMIANS APP
JAVA Interfaces and Abstract Classes interface Base{ boolean m1 (); byte m2(short s);}which two code fragments will compile?1. interface Base2 implements Base {}2. abstract class Class2 extends Base { public boolean m1(){ return true; }}3. abstract class Class2 implements Base {}4. abstract class Class2 implements Base { public boolean m1(){ return (7 > 4); }}5. abstract class Class2 implements Base { protected boolean m1(){ return (5 > 7) }} 2 and 3 4 and 5 1 and 2 3 and 4 1 and 3 2 and 3 4 and 5 1 and 2 3 and 4 1 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 method numberOfStudent() in class School must have a body. You must add a return statement in method numberOfStudent(). Class School must be defined abstract. The keywords public and abstract cannot be used together. The method numberOfStudent() in class School must have a body. You must add a return statement in method numberOfStudent(). Class School must be defined abstract. The keywords public and abstract cannot be used together. 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(); 1 and 2 3 and 4 2 and 4 1 and 3 2 and 3 1 and 2 3 and 4 2 and 4 1 and 3 2 and 3 ANSWER DOWNLOAD EXAMIANS APP
JAVA Interfaces and Abstract Classes interface Test{ int p = 10; //line 1 public int q = 20; //line 2 public static int r = 30; //line 3 public static final int s = 40; //line 4}Which of the above line will give compilation error? 3 4 1 None of these 2 3 4 1 None of these 2 ANSWER DOWNLOAD EXAMIANS APP
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