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Q4. Define a class called Library with the following description:
Instance variables/data members:
-
int acc_num – stores the accession number of the book
-
String title – stores the title of the book
-
String author – stores the name of the author
Member Methods:
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void input() – to input and store the accession number, title and author
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void compute() – to accept the number of days late, calculate and display the fine charged at the rate of Rs. 2 per day
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void display() – to display the details in following format
Accession Number Title Author
---------------- ----- ------
Write a main method to create an object of the class and call the above member methods.
[15 marks]
A4.
import java.util.*;
class Library
{
// instance variables, data members
int acc_num;
String title, author;
// zero argument constructor
public Library()
{
acc_num = 0;
title = "";
author = "";
}
// input
public void input()
{
Scanner sc = new Scanner( System.in );
String temp = "";
System.out.print("Enter the accession number: ");
acc_num = sc.nextInt();
temp = sc.nextLine(); // for the trailing newline
System.out.print("Enter the title: ");
title = sc.nextLine();
System.out.print("Enter the author: ");
author = sc.nextLine();
}
// compute and display the fine charged
public void compute(int nDays)
{
int fine = nDays * 2;
System.out.println("Fine charged: " + fine);
}
// display the info
public void display()
{
printInt(acc_num, 16+1); // print acc_num in width of 16
printStr(title, 30+1); // print title in width of 30
printStr(author, 20); // print author in width of 20
System.out.println();
}
// static method to print the header once only
public static void displayHeader()
{
printStr("Accession Number", 16+1);
printStr("Title", 30+1);
printStr("Author", 20);
System.out.println();
printStr("----------------", 16+1);
printStr("------------------------------", 30+1);
printStr("--------------------", 20);
System.out.println();
}
// main method
public static void main(String[] args)
{
Library book1 = new Library();
Library book2 = new Library();
book1.input();
book2.input();
book1.compute(5);
book2.compute(7);
Library.displayHeader();
book1.display();
book2.display();
}
// print argument1 in a field of width argument2
public static void printInt(int n, int width)
{
String s = "" + n;
printStr(s, width); // call the String method
}
// print argument1 in a field of width argument2
public static void printStr(String s, int width)
{
System.out.print(s);
// print spaces to fill up the field width
for(int i=s.length()+1; i<=width; i++)
System.out.print(" ");
}
}
harshraj
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