I'm a beginner at Java so sorry for the mess ups.
Im creating a Library program and have 4 classes: Library, Book, BookInterface and Patron.
I'm in the last couple of stages of the program however I have error messages in the Library class as I'm having trouble with instances.
I got the error message "Cannot make a static reference to the non-static method" in ALL of my switch statements. I tried to create an instance of the Library class in case 1 but still an error message. Also I can't change those methods to static. Any help is much appreciated! :)
Library class:
import java.awt.List;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;
import java.util.Collections;
public class Library
{
public static void main(String[] args)
{
//create new library
Library newLibrary = new Library();
}
public Library()
{
Library library = new Library();
Scanner input = new Scanner(System.in);
int choice = 0;
System.out.println("********************Welcome to the Public Library!********************");
System.out.println(" Please Select From The Following Options: ");
System.out.println("**********************************************************************");
while(choice != 9)
{
System.out.println("1: Add new patron");
System.out.println("2: Add new book");
System.out.println("3: Edit patron");
System.out.println("4: Edit book");
System.out.println("5: Display all patrons");
System.out.println("6: Display all books");
System.out.println("7: Check out book");
System.out.println("8: Check in book");
System.out.println("9: Search book");
System.out.println("10: Search Patron");
System.out.println("11: Exit");
choice = input.nextInt();
switch(choice)
{
case 1: //Add new patron
//ERROR: Patron cannot be resolved or is not a field
library.Patron.newPatron();
break;
case 2: //Add new book
//ERROR: Cannot make a static reference to the non-static method
Book.addBook();
break;
case 3: //Edit patron name
Patron.editName();
break;
case 4: //edit book
//ERROR: Cannot make a static reference to the non-static method
Book.editBook();
break;
case 5: //display all patrons
System.out.println(Book.UserList);
break;
case 6: //display all books
//System.out.println(Book.OrigBookList);
Book.libraryInventory();
//Book.bookStatus()
break;
case 7: //check out a book
//ERROR: Cannot make a static reference to the non-static method
Patron.CheckOutBook();
break;
case 8: //check in a book
//ERROR: Cannot make a static reference to the non-static method
Patron.CheckInBook();
break;
case 9: //search book
//ERROR: Cannot make a static reference to the non-static method
Patron.bookStatus();
break;
case 10://search Patron
Patron.searchPatron();
break;
case 11: //exit program
}
}
}
}
Book class:
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
public class Book implements BookInterface
{
Scanner input = new Scanner(System.in);
static ArrayList <String> UserList = new ArrayList<String>();
static ArrayList <String> BookList = new ArrayList <String> (); //display just titles// use when checking out books
static ArrayList <String> OrigBookList = new ArrayList <String> (); //keep track of all titles ever entered
public String title;
public String author;
public String book;
public boolean checkIn;
private String status;
private String borrower;
public Book(String t, String a)
{
title = t;
author = a;
}
//constructor create new book
public Book(String newTitle)
{
title = newTitle;
}
public String toString()
{
return title + " " + author;
}
public String getTitle()
{
return title;
}
public void setTitle(String title)
{
this.title = title;
}
public String getAuthor()
{
return author;
}
public void setAuthor(String author)
{
this.author = author;
}
public void addBook()
{
Scanner input = new Scanner(System.in);
Scanner inputread = new Scanner(System.in);
System.out.print("Enter book title: ");
String title1 = inputread.nextLine();
Scanner input1 = new Scanner(System.in);
System.out.print("Enter book author: ");
String author1 = inputread.next();
Book fullBook = new Book(title1, author1); //create constructor w/ title & author
Book book1 = new Book(title1); //constructor w/ just title to be used to display all books
//BookList.add(title1);
OrigBookList.add(title1);
setStatus("IN"); //false = checked in
System.out.println("-----------------------------------------------");
System.out.println("-----" + title1 + " is now in the library!-----");
System.out.println("-----------------------------------------------");
}
public void editBook()
{
Scanner inputread = new Scanner(System.in);
System.out.println("Enter original book title: ");
String origTitle = inputread.nextLine();
System.out.println("Enter edited book title: ");
String editedTitle = inputread.nextLine();
Collections.replaceAll(Book.UserList, origTitle, editedTitle);
System.out.println("------------------------------------------------------");
System.out.println(origTitle + " has been changed to " + editedTitle + "!");
System.out.println("------------------------------------------------------");
}
public String getStatus(String book)
{
return status;
}
public void setStatus(String status)
{
this.status = status;
}
public void setBorrower(String borrower)
{
this.borrower = borrower;
}
public String getBorrower(String checkPatron)
{
return borrower;
}
public String getBook(String checkPatron)
{
return book;
}
public void setBook(String bookCheckOut)
{
this.book = bookCheckOut;
}
public void libraryInventory()
{
System.out.println("------------------ Library Inventory: ---------------");
for(int i =0; i<= OrigBookList.size()-1; i++)
{
//Book Title: checked in/out
System.out.println(OrigBookList.get(i) + ":" + getStatus(OrigBookList.get(i)));
}
System.out.println("-----------------------------------------------------");
}
}
Patron class:
import java.text.DateFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Scanner;
public class Patron
{
Scanner input = new Scanner(System.in);
private String fullName;
int bookCount = 0; //amount books user has in pocket
int books = 0;
//constructor to "add new patron" by entering their name.
public Patron(String newName)
{
fullName = newName;
}
public String toString()
{
return fullName;
}
public String getName()
{
return fullName;
}
public void CheckOutBook()
{
//create and format due date (7days)
GregorianCalendar returnDate = new GregorianCalendar();
returnDate.add(GregorianCalendar.DATE, 7);
Date d = returnDate.getTime();
DateFormat df = DateFormat.getDateInstance();
String dueDate = df.format(d);
Scanner inputread = new Scanner(System.in);
Scanner input = new Scanner(System.in);
System.out.println("Enter full patron name: ");
String borrower = inputread.nextLine();
System.out.println("Enter book title to check out: ");
String bookCheckOut = inputread.nextLine();
Book checkOut = new Book(bookCheckOut);
if(Book.BookList.contains(bookCheckOut))
{
Book.BookList.remove(bookCheckOut);
checkOut.setStatus("OUT");
checkOut.setBorrower(borrower);
Book.BookList.remove(bookCheckOut);
System.out.println("----------" + bookCheckOut + " has been checked out!----------");
System.out.println("-------------------BOOK STATUS:---------------------");
System.out.println("Book Title: " + bookCheckOut);
System.out.println("Book Status: Checked out");
System.out.println("Borrower: " + borrower);
System.out.println("Due Date: " + dueDate);
System.out.println("----------------------------------------------------");
}
else if (!(Book.UserList.contains(borrower)))
{
System.out.println("Patron is not a part of library system. Please enter patron in system.");
}
else if (!(Book.BookList.contains(bookCheckOut)))
{
System.out.println(bookCheckOut + " is not in the library. Please enter "
+ "a different book to be checked out");
}
}
public void CheckInBook()
{
Scanner inputread = new Scanner(System.in);
System.out.println("Enter book title to be checked in: ");
String bookCheckIn = inputread.nextLine();
Book checkOut = new Book(bookCheckIn);
if((!Book.BookList.contains(bookCheckIn)) && Book.OrigBookList.contains(bookCheckIn))
{
Book.BookList.add(bookCheckIn);
checkOut.setStatus("IN");
System.out.println("------------------------------------------------------");
System.out.println("-----" + bookCheckIn + " has been checked in!-----");
System.out.println("------------------------------------------------------");
}
else
System.out.println(bookCheckIn + " is not part of the library system. Please enter "
+ "a different book to be checked in");
}
public boolean canBorrow()
{
if(bookCount <= 3)
{
return true;
}
else
{
return false;
}
}
public static void editName()
{
Scanner inputread = new Scanner(System.in);
System.out.println("Enter original patron full name: ");
String origName = inputread.nextLine();
System.out.println("Enter edited patron full name: ");
String editedName = inputread.nextLine();
Collections.replaceAll(Book.UserList, origName, editedName);
System.out.println("------------------------------------------------------");
System.out.println(origName + " has been changed to " + editedName + "!");
System.out.println("------------------------------------------------------");
}
public void newPatron()
{
Scanner inputread = new Scanner(System.in);
System.out.println("Enter patron full name: ");
String name = inputread.nextLine();
Book.UserList.add(name); //add name to userList
Patron patron1 = new Patron(name);
System.out.println("-----------------------------------------------------------------");
System.out.println("-----" + name + " has been added to the library system" + "-----");
System.out.println("-----------------------------------------------------------------");
}
public void bookStatus() //STOPS
{
Scanner input = new Scanner(System.in);
Scanner inputread = new Scanner(System.in);
System.out.println("Enter book title: ");
String checkStatus = inputread.nextLine();
Book status = new Book(checkStatus);
if(Book.OrigBookList.contains(checkStatus) && status.getStatus(checkStatus) == "OUT")
{
System.out.println("Status: checked out");
System.out.println("Borrower: " + status.getBorrower(checkStatus));
}
else if(Book.OrigBookList.contains(checkStatus) && status.getStatus(checkStatus) == "IN")
{
System.out.println("Status: checked in");
System.out.println("Borrower: none");
}
else if(!(Book.OrigBookList.contains(checkStatus)))
System.out.print("Book is not in library system. Please add the book first.");
}
public void searchPatron() //WORKS!!!
{
Scanner inputread = new Scanner(System.in);
System.out.println("Enter patron full name: ");
String checkPatron = inputread.nextLine();
Book search = new Book(checkPatron);
if(Book.UserList.contains(checkPatron))
{
System.out.println("-------------------------------------------------");
System.out.println("Books checked out: " + search.getBook(checkPatron));
System.out.println("-------------------------------------------------");
}
else
System.out.println("Patron is not part of the library system. Please create new patron first.");
}
}
Since you're calling non static methods of Patron and Book you have to make their objects to call these methods. Only static methods can be called directly on the Class. Check links below for details on static members
https://docs.oracle.com/javase/tutorial/java/nutsandbolts/variables.html
https://docs.oracle.com/javase/tutorial/java/javaOO/classvars.html
Couple of things to keep in mind
Here's the corrected code
import java.awt.List;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;
import java.util.Collections;
public class Library {
public static void main(String[] args) {
// create new library
Library newLibrary = new Library();
}
public Library() {
Scanner input = new Scanner(System.in);
int choice = 0;
System.out
.println("********************Welcome to the Public Library!********************");
System.out
.println(" Please Select From The Following Options: ");
System.out
.println("**********************************************************************");
while (choice != 9) {
System.out.println("1: Add new patron");
System.out.println("2: Add new book");
System.out.println("3: Edit patron");
System.out.println("4: Edit book");
System.out.println("5: Display all patrons");
System.out.println("6: Display all books");
System.out.println("7: Check out book");
System.out.println("8: Check in book");
System.out.println("9: Search book");
System.out.println("10: Search Patron");
System.out.println("11: Exit");
choice = input.nextInt();
//creating Patron and Book objects
Patron patron = new Patron();
Book book = new Book();
switch (choice) {
case 1: // Add new patron
// ERROR: Patron cannot be resolved or is not a field
patron.newPatron();
break;
case 2: // Add new book
// ERROR: Cannot make a static reference to the non-static
// method
book.addBook();
break;
case 3: // Edit patron name
patron.editName();
break;
case 4: // edit book
// ERROR: Cannot make a static reference to the non-static
// method
book.editBook();
break;
case 5: // display all patrons
System.out.println(Book.UserList);
break;
case 6: // display all books
// System.out.println(Book.OrigBookList);
Book.libraryInventory();
// Book.bookStatus()
break;
case 7: // check out a book
// ERROR: Cannot make a static reference to the non-static
// method
patron.CheckOutBook();
break;
case 8: // check in a book
// ERROR: Cannot make a static reference to the non-static
// method
patron.CheckInBook();
break;
case 9: // search book
// ERROR: Cannot make a static reference to the non-static
// method
patron.bookStatus();
break;
case 10:// search Patron
patron.searchPatron();
break;
case 11: // exit program
//added exit(0)
System.exit(0);
}
}
}
}
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.