How to get data of an object that already existed in one class in another file and use it to another class in another file in Java?
Question
I have to create and use LinkedList (implement from scratch) to work with the Book Library Management Program. I have 3 files which contain different classes, 3 main classes in 3 files are the BookList - which is a list of Books, ReaderList - which stores the list of readers and LendingList - which is used for storing the List of lending purposes. The BookList and ReaderList are type of Book and Reader respectly, I want to extract the current data from bookCode property of the Book class and readerCode property of the Reader class.
Input data Allow a user to input lending item. When running, the screen looks like:
Enter book code:
Enter reader code:
Enter state:
After the user enter bcode and rcode, the program check and acts as follows:
- If bcode not found in the books list or rcode not found in the readers list then data is not accepted.
- If both bcode and rcode found in the lending list and state=1 then data is not accepted.
- If bcode and rcode found but lended = quantity then new lending item with state = 0 is added to the end of the Lending list.
- If bcode and rcode found and lended < quantity then lended is increased by 1 and new lending item with state = 1 is added to the end of the Lending list.
The Books file:
package BooksPackage;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Scanner;
import java.util.Set;
/**
*
* @author Do Van Nam
*/
class Book {
String bcode;
String btitle;
int quantity;
int lended;
double price;
Book(String code, String title, int quantity, int lended, double price) {
this.bcode = code;
this.btitle = title;
this.quantity = quantity;
this.lended = lended;
this.price = price;
}
@Override
public String toString() {
return "Book{" + "bcode=" + bcode + ", btitle=" + btitle + ", quantity=" + quantity + ", lended=" + lended + ", price=" + price + '}';
}
}
class List {
private static class Node {
Book element;
Node next;
public Node(Book e, Node next) {
this.element = e;
this.next = next;
}
public Node(Book e) {
this(e, null);
}
public Node getNext() {
return next;
}
public Book getElement() {
return element;
}
public void setNext(Node e) {
this.next = e;
}
}
Node head = null;
Node tail = null;
int size = 0;
public List() {
}
public boolean isEmpty() {
return size == 0;
}
public Book getFirst() {
if (isEmpty()) {
return null;
}
return head.element;
}
public Book getLast() {
if (isEmpty()) {
return null;
}
return tail.element;
}
public void addFirst(Book e) {
head = new Node(e, head);
if (size == 0) {
tail = head;
}
size++;
}
public void addLast(Book e) {
Node last = new Node(e, null);
if (isEmpty()) {
head = last;
} else if (size == 1) {
head.setNext(last);
tail = last;
} else {
tail.setNext(last);
tail = last;
}
size++;
}
public void removeFirst() {
if (isEmpty()) {
return;
}
head = head.getNext();
size--;
}
public void removeLast() {
if (isEmpty()) {
return;
}
Node secondLast = head;
while (secondLast.next.next != null) {
secondLast = secondLast.next;
}
secondLast.next = null;
size--;
}
public boolean isDuplicate(String code) {
Node node = head;
while (node != null) {
if (node.element.bcode.equals(code)) {
return true;
}
node = node.next;
}
return false;
}
public String displayNode() {
Node node = head;
double value;
String a = "";
while (node != null) {
value = node.element.price * node.element.quantity;
a += node.element.bcode + "\t" + node.element.btitle + "\t" + node.element.quantity + "\t" + node.element.lended + "\t" + node.element.price + "\t" + value + "\n";
node = node.getNext();
}
return a;
}
public Node searchByCode(String code) {
Node x = head;
while (x != null) {
if (x.element.bcode.equals(code)) {
return x;
}
x = x.getNext();
}
return null;
}
public void deleteByCode(String code) {
Node x = head;
if (x.element.bcode.equals(code)) {
head = head.next;
size--;
return;
}
while (x.next != null) {
if (x.next.element.bcode.equals(code)) {
x.next = x.next.next;
size--;
return;
}
x = x.next;
}
}
public void sortByBCode() {
Node a, b;
Book obj;
a = head;
while (a != null) {
b = a.next;
while (b != null) {
if (b.element.bcode.compareTo(a.element.bcode) < 0) {
obj = a.element;
a.element = b.element;
b.element = obj;
}
b = b.next;
}
a = a.next;
}
}
public void insertAfter(Node node, Book book) {
if (isEmpty() || node == null) {
return;
}
Node after = node.next;
Node newNode = new Node(book, after);
node.next = newNode;
if (tail == node) {
tail = newNode;
}
size++;
}
public Node nodeAtPos(int pos) {
int i = 0;
Node init = head;
while (init != null) {
if (i == pos) {
return init;
}
i++;
init = init.next;
}
return null;
}
public void deleteAtPostion(int pos) {
if (isEmpty()) {
return;
}
Node temp = head;
if (pos == 0) {
head = head.next;
return;
}
for (int i = 0; temp != null && i < pos - 1; i++) {
temp = temp.next;
}
if (temp == null || temp.next == null) {
return;
}
Node next = temp.next.next;
temp.next = next;
}
public static void main(String[] args) throws IOException {
Scanner sc = new Scanner(System.in);
// 1
List bookList = new List();
// 2
// a.addFirst(new Book("SA", "SOMETHING", 12, 23, 122));
// a.addFirst(new Book("SAX", "SOMETHING", 12, 23, 122));
// a.addFirst(new Book("SAC", "SOMETHING", 12, 23, 122));
// a.addFirst(new Book("SAD", "SOMETHING", 12, 23, 122));
System.out.println("1.1. Load data from file\n"
+ "1.2. Input & add to the end\n"
+ "1.3. Display data\n"
+ "1.4. Save book list to file\n"
+ "1.5. Search by bcode\n"
+ "1.6. Delete by bcode\n"
+ "1.7. Sort by bcode\n"
+ "1.8. Input & add to beginning\n"
+ "1.9. Add after position k\n"
+ "1.10. Delete position k");
int option;
do {
System.out.println("Choose an option from 1 to 10, press 0 to stop");
option = sc.nextInt();
if (option == 1) {
System.out.println("Enter the file you want to read");
String file = sc.next();
// the file will be using here is test.txt, which is existed on my local computer, you should try by entering the file you want to read on your computer instead.
BufferedReader read = new BufferedReader(new FileReader(file));
String str;
while ((str = read.readLine()) != null) {
System.out.println(str);
}
}
if (option == 2) {
System.out.println("Enter the book");
String bcode = sc.next();
String btitle = sc.next();
int quantity = sc.nextInt();
int lended = sc.nextInt();
double price = sc.nextDouble();
if (!bookList.isDuplicate(bcode)) {
bookList.addLast(new Book(bcode, btitle, quantity, lended, price));
} else {
System.out.println("This book is already in the list.");
}
}
if (option == 3) {
System.out.println("code" + "\t" + "Title" + "\t" + "Quantity" + "\t" + "Lended" + "\t" + "Price" + "\t" + "Value");
System.out.println("-------------------------------------------------------------------");
System.out.println(bookList.displayNode());
}
if (option == 4) {
System.out.println("Enter the file name");
String fileName = sc.next();
File input = new File(fileName);
if (input.createNewFile()) {
FileWriter fr = null;
BufferedWriter br = null;
String content = bookList.displayNode();
try {
fr = new FileWriter(input);
br = new BufferedWriter(fr);
// String[] lines = content.split("\r\n|\r|\n");
// int linesNums = lines.length;
br.write(content);
} catch (IOException e) {
e.printStackTrace();
} finally {
br.close();
fr.close();
}
}
}
if (option == 5) {
System.out.println("Enter the code of the book you are searching");
String code = sc.next();
if (bookList.searchByCode(code) != null) {
System.out.println(bookList.searchByCode(code));
} else {
System.out.println("Not found");
}
}
if (option == 6) {
System.out.println("Enter the code of the book you want to delete");
String code = sc.next();
bookList.deleteByCode(code);
}
if (option == 7) {
bookList.sortByBCode();
}
if (option == 8) {
System.out.println("Enter the book you want to add to the beginning of the list");
System.out.println("How many books you want to add?");
int nums = sc.nextInt();
while (nums != 0) {
System.out.println("Enter bcode, title, quantity, lended and price for this book");
String bcode = sc.next();
String title = sc.next();
int quantity = sc.nextInt();
int lended = sc.nextInt();
double price = sc.nextDouble();
bookList.addFirst(new Book(bcode, title, quantity, lended, price));
nums--;
}
}
if (option == 9) {
System.out.println("Insert a new node after the bcode: ");
String code = sc.next();
System.out.println("Enter the book");
String bcode = sc.next();
String title = sc.next();
int quantity = sc.nextInt();
int lended = sc.nextInt();
double price = sc.nextDouble();
Book newBook = new Book(bcode, title, quantity, lended, price);
bookList.insertAfter(bookList.searchByCode(code), newBook);
}
if (option == 10) {
System.out.println("Enter the position you want to delete");
int pos = sc.nextInt();
bookList.deleteAtPostion(pos);
}
} while (option != 0);
}
}
The Reader file:
package BooksPackage;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
/**
*
* @author VanNam
*/
class Reader {
private String rcode;
private String name;
private int byear;
Reader(String rcode, String name, int byear) {
this.rcode = rcode;
this.name = name;
this.byear = byear;
}
@Override
public String toString() {
return "Reader{" + "rcode=" + rcode + ", name=" + name + ", byear=" + byear + '}';
}
public String getRcode() {
return rcode;
}
public void setRcode(String rcode) {
this.rcode = rcode;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getByear() {
return byear;
}
public void setByear(int byear) {
this.byear = byear;
}
}
class XList {
private static class Node {
Reader element;
Node next;
public Node(Reader e, Node next) {
this.element = e;
this.next = next;
}
public Node(Reader e) {
this(e, null);
}
public Node getNext() {
return next;
}
public Reader getElement() {
return element;
}
public void setNext(Node e) {
this.next = e;
}
}
public XList() {
head = tail = null;
}
Node head = null;
Node tail = null;
int size = 0;
public boolean isEmpty() {
return size == 0;
}
public Reader getFirst() {
return head.getElement();
}
public Reader getLast() {
return tail.getElement();
}
public void addFirst(Reader e) {
head = new Node(e, head);
if (size == 0) {
tail = head;
}
size++;
}
public void addLast(Reader e) {
Node last = new Node(e, null);
if (size == 0) {
head = last;
} else if (size == 1) {
head.setNext(last);
tail = last;
} else {
tail.setNext(last);
tail = last;
}
size++;
}
public String displayNode() {
Node node = head;
String a = "";
while (node != null) {
a += node.element.getRcode() + "\t" + node.element.getName() + "\t" + node.element.getByear() + "\n";
node = node.getNext();
}
return a;
}
public Node searchByCode(String code) {
Node x = head;
while (x != null) {
if (x.element.getRcode().equals(code)) {
return x;
}
x = x.getNext();
}
return null;
}
public void deleteByCode(String code) {
Node x = head;
if (x.element.getRcode().equals(code)) {
head = head.next;
size--;
return;
}
while (x.next != null) {
if (x.next.element.getRcode().equals(code)) {
x.next = x.next.next;
size--;
return;
}
x = x.next;
}
System.out.println("Not found this reader on the list");
}
public boolean isDuplicate(String code) {
Node node = head;
while (node != null) {
if (node.element.getRcode().equals(code)) {
return true;
}
node = node.getNext();
}
return false;
}
public static void main(String[] args) throws FileNotFoundException, IOException {
XList readerList = new XList();
int option;
System.out.println("2.1. Load data from file\n"
+ "2.2. Input & add to the end\n"
+ "2.3. Display data\n"
+ "2.4. Save reader list to file\n"
+ "2.5. Search by rcode\n"
+ "2.6. Delete by rcode");
do {
Scanner sc = new Scanner(System.in);
System.out.println("Choose an option");
option = sc.nextInt();
if (option == 1) {
System.out.println("Enter the file you wanna read");
String file = sc.next();
// the file will be using here is testReader.txt, which is existed on my local computer, you should try by entering the file you want to read on your computer instead.
BufferedReader read = new BufferedReader(new FileReader(file));
String str;
while ((str = read.readLine()) != null) {
System.out.println(str);
}
}
if (option == 2) {
System.out.println("Enter the reader");
String code = sc.next();
String name = sc.next();
int year = sc.nextInt();
if (!readerList.isDuplicate(code)) {
readerList.addLast(new Reader(code, name, year));
} else {
System.out.println("This reader is already in the list.");
}
}
if (option == 3) {
System.out.println(readerList.displayNode());
}
if (option == 4) {
System.out.println("Enter the file name");
String fileName = sc.next();
File input = new File(fileName);
if (input.createNewFile()) {
FileWriter fr = null;
BufferedWriter br = null;
String content = readerList.displayNode();
try {
fr = new FileWriter(input);
br = new BufferedWriter(fr);
br.write(content);
} catch (IOException e) {
e.printStackTrace();
} finally {
br.close();
fr.close();
}
}
}
if (option == 5) {
System.out.println("Find the reader by entering the code");
String code = sc.next();
if (readerList.searchByCode(code) != null) {
System.out.println("Found at this address: " + readerList.searchByCode(code));
} else {
System.out.println("Not found");
};
}
if (option == 6) {
System.out.println("Enter the reader you want to delete by entering the code");
String code = sc.next();
readerList.deleteByCode(code);
}
} while (option != 0);
}
}
The LendingBook file:
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package BooksPackage;
import java.util.Scanner;
/**
*
* @author VanNam
*/
public class LendingBook {
private String bcode;
private String rcode;
private int state;
public LendingBook(String bcode, String rcode, int state) {
this.bcode = bcode;
this.rcode = rcode;
this.state = state;
}
@Override
public String toString() {
return "LendingBook{" + "bcode=" + bcode + ", rcode=" + rcode + ", state=" + state + '}';
}
public String getBcode() {
return bcode;
}
public void setBcode(String bcode) {
this.bcode = bcode;
}
public String getRcode() {
return rcode;
}
public void setRcode(String rcode) {
this.rcode = rcode;
}
public int getState() {
return state;
}
public void setState(int state) {
this.state = state;
}
}
class LendingList {
private static class Node{
private LendingBook element;
private Node next;
public Node(LendingBook e, Node n){
this.element = e;
this.next = n;
}
public Node(LendingBook e){
this(e, null);
}
public Node getNext() {
return next;
}
public LendingBook getElement() {
return element;
}
public void setNext(Node n){
this.next = n;
}
}
Node head = null;
Node tail = null;
int size = 0;
public boolean isEmpty(){
return size == 0;
}
public LendingBook getFirst() {
if(isEmpty()) return null;
return head.getElement();
}
public static void main(String[] args){
Scanner sc = new Scanner(System.in);
LendingList lendingList = new LendingList();
int option;
do{
System.out.println("Enter the option" + "\n" + "1.Input data 2. Display lending data 3. Sort by bcode + rcode" + "\n" + "Press 0 to exit");
option = sc.nextInt();
if(option == 1){
String bookCode; // -> Here, I want to check it with the existing bookCode from the Book file
String readerCode; // // -> Here, I want to check it with the existing readerCode from the Reader file
int state;
System.out.println("Enter book code");
bookCode = sc.next();
System.out.println("Enter the reader code");
readerCode = sc.next();
}
}while(option != 0);
}
}
I want to get that information and use the data from the two classes above in my LendingList. Many thanks.
1 answers
solution1
0 2020-02-25 03:07:26
You can only pass data using constructors or instance methods.
or do
filename bob = new filename(object or data type);
bob.method(object or data type);
PS : Not sure if this is going to work.
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