Show the output of running the class Test in the following code lines: interface A { } class C{ } class D extends C{ } class B extends D implements A { } public class Test { public static void main(String[] args) { Bb. = new B(); if (b instanceof A) System.out.println("b is an instance of A"); if (b instanceof C) System.out.printin("b is an instance of C"); } }

Show the output of running the class Test in the following code lines: interface A { } class C{ } class D extends C{ } class B extends D implements A { } public class Test { public static void main(String[] args) { Bb. = new B(); if (b instanceof A) System.out.println("b is an instance of A"); if (b instanceof C) System.out.printin("b is an instance of C"); } }

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Subject : object Orieted Programming Q: Find the error in the following given codes and rewrite. a). public interface intt { public void P1 (String p) { System.out.println ("figure is " + p ); } public double p2 ( ) ; } b). class B { final void r() { System.out.println("run");} } class H implements B { void r() { System.out.println("run run"); } public static void main(String args[]) { H h= new H(); h.r(); } }
3. Consider the following two classes and write down the output of the following code: public class Test extends G{ void display() { String s = m1(); System.out.println("My name is "+ s); i - 7; j = j + i; } void show(){ System.out.println(" j value is - } public static void main(String args[]) { Test t - new Test(); System.out.println("s value is = t.display(); t.i = 9; System.out.println("i value in the object="+t.i); System.out.println("j value in the object="+t.j); t.show(); } abstract class G{ String s - "Exam"; int i = 10; int j - 5; String m1(){ s = "Java"; return s; abstract void display(); abstract void show( ); } " + j); + t.s);
Analyse the following code. public class Test { int x; public Test(String t) { System.out.println("Test"); } public static void main(String[] args) { Test test = new Test(); System.out.println(test.x); } } A. The program has a compile error because you cannot create an object from the class that defines the object. B. The program has a compile error because System.out.println method cannot be invoked from the constructor. C. The program has a compile error because x has not been initialized. D. The program has a compile error because Test does not have a default constructor.
2. Using Encapsulation concept for Test1 class. package Exam; public class Test1 { private static int index = 0; public int x; Test1(){ index ++; } public static int getlndex () { return index; } public void prints(){ System.out.println("Hi Students!"); } } public class Test2 extends Test1 { @Override public void prints(){ System.out.println("OOP!"); } } public class Main { public static void main(String[] args) { } }
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1) The UsingMethod class consists of a main method and a method called xMethod. What will the code print? public class UsingMethod {public static void main(String[] args) {double z = xMethod(3.5, 5.5);System.out.println(z);}public static double xMethod(double x, double y) {return x + y;}} 2) Identify the errors in the following programs a) 3 errorspublic class Test {public static void main(String[] args) {System.out.println(method2(3.4));} public static int method1(int n) {if (n > 0) return 1;else if (n == 0) return 0;else if (n < 0) return -1;}} b) 2 errorspublic class Test {public static void main(String[] args) {nPrintln(5, "Welcome to Java!");}public static void nPrintln(String message, int n) {for (int i = 0; i < n; i++) {System.out.println(message);}return n;}}
Description: Create a class named ComparableDog that extends Animal and implements Comparable interface. Implement the compareTo method to compare the Dogs on the basis of age. Write a test class to find the bigger age of two instances of ComparableDog Objects, and complement the ComparableDog class with the missing part. 1) The test program, the ComparableDog class, and its super class Animal are given as follows. // Main method public static void main(String[] args) { // Create two comparable Dogs ComparableDog dog1 = new ComparableDog(3); ComparableDog dog2 = new ComparableDog(4); System.out.println("Dog1:" + dog1); System.out.println("Dog2:" + dog2); if(dog1.compareTo(dog2) == 1) System.out.println("Dog1 is older than Dog2"); else if(dog1.compareTo(dog2) == -1) System.out.println("Dog1 is younger than Dog2"); else System.out.println("Dog1 and Dog2 have the same age"); }…
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What is the output of the following code with explanation:- class Teacher { public Teacher() { System.out.println("Teacher class constructor called"); } } public class Student extends Teacher { public Student() { System.out.println("Student class constructor called"); } public static void main (String args[]) { Student s = new Student(); } }
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