如何獲取另一個文件中一個類中已經存在的對象的數據，並將其用於Java中另一個文件中的另一個類？
[英]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?
問題描述
我必須創建和使用 LinkedList（從頭開始實施）才能與圖書圖書館管理程序一起工作。 我有 3 個包含不同類的文件，3 個文件中的 3 個主要類是 BookList - 它是書籍列表，ReaderList - 存儲讀者列表和 LendingList - 用於存儲借出目的列表。 該書目和ReaderList是圖書和閱讀器的類型respectly，我想提取從當前數據bookCode Book類的屬性和readerCode Reader類的屬性。
輸入數據 允許用戶輸入借出項目。 運行時，屏幕如下所示：
輸入圖書代碼：
輸入閱讀器代碼：
進入狀態：
用戶輸入 bcode 和 rcode 后，程序檢查並執行如下操作：
- 如果在書籍列表中未找到 bcode 或在讀者列表中未找到 rcode，則不接受數據。
- 如果在借出列表中找到 bcode 和 rcode 並且 state=1，則不接受數據。
- 如果找到 bcode 和 rcode 但已借出 = 數量，則將狀態 = 0 的新借出項目添加到 Lending 列表的末尾。
- 如果找到 bcode 和 rcode 並且借出 < 數量，則借出增加 1，並將狀態 = 1 的新借出項目添加到 Lending 列表的末尾。
圖書檔案：
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);
}
}
閱讀器文件：
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);
}
}
LendingBook 文件：
/*
* 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);
}
}
我想獲取該信息並在我的 LendingList 中使用來自上述兩個類的數據。 非常感謝。
1 個解決方案
解決方案1
0 2020-02-25 03:07:26
您只能使用構造函數或實例方法傳遞數據。
或做
filename bob = new filename(object or data type);
bob.method(object or data type);
PS：不確定這是否會起作用。
Java：如何從一個mouseListener到另一個類使用對象？
[英]Java: How to use an object from one mouseListener to another class?
如何使用vscode將一個文件的類導入Java子文件夾中的另一個文件
[英]How to import class of one file to another in a subfolder in Java using vscode
聲明:本站的技術帖子網頁，遵循CC BY-SA 4.0協議，如果您需要轉載，請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.