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input - Java - Reading from txt file and storing in array

问题描述:

I am working on a small library application which is able to save manuals stored to a text file, and load said text file back. However currently I am unable to store the library in an array, as once the user loads a file they are simply displayed the text within the console area.

How can I get the loaded library.txt file to be stored in the library rather than printed to the console?

Here is my manual class with the save implementation:

import java.io.*;

import java.util.Scanner;

public class Manual {

String serial;

String title;

String author;

String publicationYear;

String status;

String borrower;

String borrowDate;

String returnDate;

Scanner userInput = new Scanner(System.in);

/**

* Display the Manual:

* @return ManualInfo

*/

final String displayManual(){

String ManualInfo ="\nSerial Number: ........... "+serial+

"\nTitle: ................... "+title+

"\nAuthor: .................. "+author+

"\nPublication Year: ........ "+publicationYear+

"\nStatus: .................. "+status+

"\nBorrower: ................ "+borrower+

"\nDate Borrowed: ........... "+borrowDate+

"\nReturn date: ............. "+returnDate+

"\n";

return ManualInfo;

}

/**

* Creates the Manual.

*/

final void createManual(){

serial = Console.readString(Messages.enterSerialMessage, Messages.tooShortMessage, 3);

title = Console.readString(Messages.enterTitleMessage, Messages.tooShortMessage, 2);

author = Console.readString(Messages.enterAuthorMessage, Messages.tooShortMessage, 3);

publicationYear = Console.readString(Messages.enterPublicationYearMessage, Messages.tooShortMessage, 4);

borrower = "N/A";

borrowDate = "N/A";

returnDate = "N/A";

status = "Available";

}

/***

* Runs the main part of the program and terminates if the choice is 0.

*/

public void run(){

User.addUser();

Menu.displayMenu();//Displays the main menu and ask for choice.

exit:

while(Menu.menuChoice != 0){

if(Menu.menuChoice == 1 && Library.ManualList.size() > 0){

Library.displayManualList();

boolean saveYesNo = Console.readYesNo("The ManualKeeper® app is able to save your current library to a '.txt' \nfile in your workspace directory.\n\nWould you like to save the current library? (Y/N):\n");

if(saveYesNo){

try {

FileWriter fw = new FileWriter("Library.txt");

PrintWriter pw = new PrintWriter(fw);

for (int i1 = 0; i1 < Library.ManualList.size(); i1++){

pw.println("-------------------- Index Number: " + i1 + " --------------------");

pw.println(Library.ManualList.get(i1).displayManual());

pw.println("---------------------------------------------------------\n");

}

pw.close();

} catch (IOException e) {

System.out.println("Error! Library unable to save.");

}

System.out.println("\n\n--------------------------------------------------------------------------");

System.out.println("\n Library saved!\n");

System.out.println("--------------------------------------------------------------------------\n");

}

else if(saveYesNo){

System.out.println("\n");

}

Menu.displayMenu();

}

if(Menu.menuChoice == 1 && Library.ManualList.isEmpty()){

System.out.println(Messages.addManualFirst);

Menu.displayMenu();

}

if(Menu.menuChoice == 1 && Library.ManualList.size() > 0){

Library.displayManualList();

boolean saveYesNo = Console.readYesNo("The ManualKeeper® app is able to save your current library to a '.txt' \nfile in your workspace directory.\n\nWould you like to save the current library? (Y/N):\n");

if(saveYesNo){

try {

FileWriter fw = new FileWriter("Library.txt");

PrintWriter pw = new PrintWriter(fw);

for (int i1 = 0; i1 < Library.ManualList.size(); i1++){

pw.println("-------------------- Index Number: " + i1 + " --------------------");

pw.println(Library.ManualList.get(i1).displayManual());

pw.println("---------------------------------------------------------\n");

}

pw.close();

} catch (IOException e) {

System.out.println("Error! Library unable to save.");

}

System.out.println("\n\n--------------------------------------------------------------------------");

System.out.println("\n Library saved!\n");

System.out.println("--------------------------------------------------------------------------\n");

}

else if(saveYesNo){

System.out.println("\n");

}

Menu.displayMenu();

}

if(Menu.menuChoice == 1 && Library.ManualList.isEmpty()){

System.out.println(Messages.addManualFirst);

Menu.displayMenu();

}

Here is my startLibrary class with my load implementation:

public class startLibrary {

/**

* The main method.

*

* @param args the arguments

*/

public static void main(String[] args){

System.out.println("\n--------------------------------------------------------------------------");

System.out.println("\n Welcome to the ManualKeeper® library app!");

System.out.println("\n--------------------------------------------------------------------------\n");

boolean loadYesNo = Console.readYesNo("The ManualKeeper® app is able to load any 'Library.txt' files found in \nyour workspace directory.\n\nWould you like to load a library? (Y/N):\n");

if(loadYesNo){

try {

FileReader fr = new FileReader("Library.txt");

BufferedReader br = new BufferedReader(fr);

String str;

while ((str = br.readLine()) != null) {

System.out.println(str + "\n");

}

br.close();

} catch (IOException e) {

System.out.println("Error! File not found");

}

}

Manual newManual = new Manual();

newManual.run();

}//End of Main Method.

Here is my library class in full incase needed:

package library;

import java.util.ArrayList;

/** The Manual choice. */

public static int ManualChoice;

static String returnManualTitle;

/** The status1. */

static String status1 = "Available";

/** The status2. */

static String status2 = "Borrowed";

/** The Manual list. */

static ArrayList<Manual> ManualList = new ArrayList<Manual>();

static ArrayList<Manual> borrowedManuals = new ArrayList<Manual>();

/**

* Adds the Manual.

*/

static void addManual(){

Manual newManual = new Manual(); //create new Manual object with status "Available."

newManual.createManual();

ManualList.add(newManual);//add the Manual to the ManualList ArrayList.

System.out.println("\n\n--------------------------------------------------------------------------");

System.out.println("\n Manual added to library!\n");

System.out.println("--------------------------------------------------------------------------\n");

}

/**

* Display Manual list.

*/

static void displayManualList(){

if (ManualList.isEmpty()){//If the library is empty, it goes back to main menu and choice.

System.out.println("-------------------------------------------------------------");

System.out.println(Messages.empltyLibraryMessage + Messages.tryAgainMessage);

System.out.println("-------------------------------------------------------------");

Menu.menuChoice = 7;

} else {

System.out.printf("\n\nHere are the Manual/s currently stored in the library:\n\n\n");

for (int i = 0; i < ManualList.size(); i++){

System.out.printf("-------------------- Index Number: %s --------------------\n",i);

System.out.println(ManualList.get(i).displayManual());

System.out.println("---------------------------------------------------------\n");

}

}//End of For Loop.

}// End of Else Statement.

static void displayBorrowedManuals(){

if (ManualList.isEmpty()){//If the library is empty, it goes back to main menu and choice.

System.out.println("-------------------------------------------------------------");

System.out.println(Messages.empltyLibraryMessage + Messages.tryAgainMessage);

System.out.println("-------------------------------------------------------------");

Menu.menuChoice = 7;

} else {

for (int i = 0; i < borrowedManuals.size(); i++){

System.out.printf("-------------------- Index Number: %s --------------------\n",i);

System.out.println(borrowedManuals.get(i).displayManual());

System.out.println("---------------------------------------------------------");

}//End of For Loop.

}// End of Else Statement.

}//End of if Statement.

/**

* Borrow Manual.

*/

public static void borrowManual(){

//register user's Manual choice.

displayManualList();

ManualChoice = (Console.readInteger(Messages.enterManualIndexMessage, Messages.ManualIndexNotInListMessage, 0, Library.ManualList.size() - 1));

borrowLoop:

while(Menu.menuChoice == 3){

//Check if the Manual to be borrowed is available.

//ManualChoice = (Console.readInteger(Messages.enterManualIndexMessage, Messages.ManualIndexNotInListMessage, 1, Library.ManualList.size()));

if ((ManualList.get(ManualChoice).status.equalsIgnoreCase(status1)) && (ManualList.size() >= ManualChoice)){

//Print the borrowed Manual information and change the Manual status to borrowed.

ManualList.get(ManualChoice).status = "Borrowed";

ManualList.get(ManualChoice).borrower = User.userName;

ManualList.get(ManualChoice).borrowDate = "Today.";

ManualList.get(ManualChoice).returnDate = "In two weeks.";

//Add the borrowed Manual to the borrowedManuals arraylist:

borrowedManuals.add(ManualList.get(ManualChoice));

System.out.println("\n--------------------------------------------------------------------------");

System.out.println("\n Manual borrowed!\n");

System.out.println("--------------------------------------------------------------------------\n");

break borrowLoop;

}else if(ManualList.get(ManualChoice).status.equalsIgnoreCase(status2) && ManualList.size() >= ManualChoice){

System.out.println("\n--------------------------------------------------------------------------");

System.out.println("\n "

+ " The Manual you wish to borrow is already on loan.");

System.out.println("\n--------------------------------------------------------------------------\n");

break borrowLoop;

}else if(ManualChoice > ManualList.size()-1){

System.out.println(Messages.noSuchManualMessage);

break borrowLoop;

}

if(ManualList.size() > 1){

displayManualList();

}

else if(ManualList.size() == 1){

ManualList.get(ManualChoice).status = "Borrowed";

ManualList.get(ManualChoice).borrower = User.userName;

ManualList.get(ManualChoice).borrowDate = "Today.";

ManualList.get(ManualChoice).returnDate = "In two weeks.";

borrowedManuals.add(ManualList.get(ManualChoice));

System.out.printf("\n\nOSCAR YOU SHOULD NOT BE SEEING THIS!!!!!!!\n\n %s\n\n", ManualList.get(ManualChoice).displayManual());

System.out.println("Please return the Manual within two weeks!\n");

displayManualList();

}

}

Menu.displayMenu();

}

/**

* Return Manual.

*/

static void returnManual(){

System.out.printf("\n\nHere are the Manual/s currently out on loan:\n\n");

if(borrowedManuals.size() > 0){

for (int i = 0; i < borrowedManuals.size(); i++)

System.out.println(borrowedManuals.get(i).displayManual());

returnManualTitle = Console.readString(Messages.enterManualSerial, Messages.tooShortMessage, 3);

}

int x = 0;

boolean serialExistance = false;

while (x < ManualList.size()){//Search for the Manual by title, if it exists change it's status,

//it's borrower and borrowDate.

if (ManualList.get(x).serial.equalsIgnoreCase(returnManualTitle)){

ManualList.get(x).status = "Available";

ManualList.get(x).borrower = "N/A";

ManualList.get(x).borrowDate = "N/A";

ManualList.get(x).returnDate = "N/A";

int p = 0;

while (p < borrowedManuals.size()) {

Manual borrowed = borrowedManuals.get(p); // guessing the name of this class

if (borrowed.serial.equalsIgnoreCase(returnManualTitle)) {

borrowedManuals.remove(p);

break;

}

p++;

}

System.out.println(Messages.successReturnMessage);

serialExistance = true;

break;//if a title is found, break out of the loop and display choice menu.

}

x = x+1;

}//end of while loop.

if(serialExistance == false){

boolean repeatReturnManual = Console.readYesNo("\n--------------------------------------------------------------------------" + "\n\nThe Manual with the title "+"\""+returnManualTitle +"\""+ " wasn't found!"

+"\n\nDo you want to try again? (Y/N):\n");

System.out.println("\n--------------------------------------------------------------------------");

if(repeatReturnManual){

returnManual();

}

}else if(serialExistance){

Menu.menuChoice = 7;

}

}

/**

* Removes the Manual.

*/

public static void removeManual(){

if(ManualList.size() >0){

displayManualList();

ManualChoice = Console.readInteger(Messages.enterRemoveManualIndex ,Messages.ManualIndexNotInListMessage, 0, ManualList.size());

int p = 0;

while (p < borrowedManuals.size()){//Search for the Manual by title, if it exists change it's status,

//it's borrower and borrowDate.

if (borrowedManuals.get(p).title.equalsIgnoreCase(returnManualTitle)){

borrowedManuals.remove(p);

}

}

ManualList.remove(ManualChoice);

System.out.print(Messages.successRemovedManualMessages);

Menu.menuChoice = 7;

}

}

/**

* Empty library.

*/

static void emptyLibrary(){

System.out.println("\n WARNING!");

System.out.println("\n You have chosen to delete all Manuals in the library.\n");

System.out.println("--------------------------------------------------------------------------");

boolean emptyLibraryChoice = Console.readYesNo("\nAre you sure you wish to destroy the library? (Y/N): \n");

System.out.println("\n--------------------------------------------------------------------------\n");

if(emptyLibraryChoice){

Library.ManualList.clear();

System.out.println(Messages.successEmptyLibraryMesssage);

System.out.println("--------------------------------------------------------------------------\n");

Menu.menuChoice = 7;

}

}

}

网友答案:

I think you reposted the question. And I think the question was answered pretty good. I try to explain it to you:

You save your library as a text file. You add all manuals like this:

"-------------------- Index Number: " + i1 + " --------------------"
                    "\nSerial Number: ........... "+serial+ 
                    "\nTitle: ................... "+title+
                    "\nAuthor: .................. "+author+
                    "\nPublication Year: ........ "+publicationYear+
                    "\nStatus: .................. "+status+
                    "\nBorrower: ................ "+borrower+
                    "\nDate Borrowed: ........... "+borrowDate+
                    "\nReturn date: ............. "+returnDate+
                    "\n";
"---------------------------------------------------------\n"

Now you write many of these into the library.txt file. The problem: You cant extract the information. The solution is: PARSING. This here is just a little code you have to adapt to get it work:

    final String delimiterManuals = ";;;;;;;;";
    final String delimiterValues = "::::::::";

//save file
for (int i1 = 0; i1 < Library.ManualList.size() - 1; i1++)
{
    //here are all attributes
    pw.print(Library.ManualList.get(i1).title));
    pw.print(delimiterValues);
    pw.print(Library.ManualList.get(i1).author));
    pw.print(delimiterValues);
    pw.print(Library.ManualList.get(i1).publicationYear));
    pw.print(delimiterValues);
    pw.print(Library.ManualList.get(i1).status));
    pw.print(delimiterValues);
    pw.print(Library.ManualList.get(i1).borrower));
    pw.print(delimiterValues);
    pw.print(Library.ManualList.get(i1).borrowDate));
    pw.print(delimiterValues);
    pw.print(Library.ManualList.get(i1).returnDate); //this is your last attribute
    pw.print(delimiterManuals);
}
//WATCH: lastAttribute is just an example (because I don't want to write every attribute)
//last Manual has no delimiterManual at the end (end of file)
pw.print(Library.ManualList.get(Library.ManualList.size()-1).title));
pw.print(delimiterValues);
pw.print(Library.ManualList.get(Library.ManualList.size()-1).author));
pw.print(delimiterValues);
//other attributes of the manual...
pw.print(Library.ManualList.get(Library.ManualList.size()-1).lastAttribute);


ArrayList<String> a = new ArrayList<String>();
//load
FileReader fr = new FileReader("Library.txt");
BufferedReader br = new BufferedReader(fr);

String str;
while ((str = br.readLine()) != null)
{
    a.add(str);
}
ArrayList<Manual> manuals = new ArrayList<Manual>()
for(int i = 0; i < a.size(); ++i)
{
    //split into single manuals
    String[] split1 = a.get(i).split(delimiterManuals);
    for(int j = 0; j < split1.length; ++j)
    {
        //split into single values
        String[] split2 = split1.split(delimiterValues);
        //here you have all values of a manual in the order you saved them so:
        Manual m = new Manual();
        m.title = split[0]; // <-- please don't do this! create and use setter/getter (like m.setTitle(split[0]);
        m.author = split[1]
        // till all fields are filled up
        manuals.add(m);
    }
}

//now you have all manuals in the manuals ArrayList

Please consider, that you really have to adapt the code. I just wanted to give you a general idea of how to parse.

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