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(); 3 and 4 1 and 3 1 and 2 2 and 3 2 and 4 3 and 4 1 and 3 1 and 2 2 and 3 2 and 4 ANSWER DOWNLOAD EXAMIANS APP
JAVA Interfaces and Abstract Classes Which of the following declares an abstract method in an abstract Java class? public abstract void method(); public void abstract Method(); public void method() {} public abstract method(); public abstract void method() {} public abstract void method(); public void abstract Method(); public void method() {} public abstract method(); public abstract void method() {} 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 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. 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 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 Compilation fails due to an error on lines 1 test-name Compilation fails due to an error on lines 2 ANSWER DOWNLOAD EXAMIANS APP
JAVA Interfaces and Abstract Classes What will be the output?interface A{public void method();}class One{public void method(){System.out.println("Class One method");}}class Two extends One implements A{public void method(){System.out.println("Class Two method");}}public class Test extends Two{public static void main(String[] args){A a = new Two();a.method();}} None of these will print Class Two method Compilation Error will print Class One method compiles fine but print nothing None of these will print Class Two method Compilation Error will print Class One method compiles fine but print nothing 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? Class School must be defined abstract. The keywords public and abstract cannot be used together. You must add a return statement in method numberOfStudent(). The method numberOfStudent() in class School must have a body. Class School must be defined abstract. The keywords public and abstract cannot be used together. You must add a return statement in method numberOfStudent(). The method numberOfStudent() in class School must have a body. ANSWER DOWNLOAD EXAMIANS APP
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