如何在GUI程序运行之前读取文本文件

Question

我已经在论坛中进行了搜索，但仍然没有找到解决方案。

我正在制作一个带有GUI程序的库。我想要的是通过文本文件保存条目。我可以使用我拥有的方法创建对象，并可以轻松地将它们保存到文件中。问题来自于再次启动程序并使用文本文件中的值填充Vector。我正在添加的对象具有String值，后跟7个布尔值。当我尝试从文件加载时，String值为空（“”）并且所有布尔值都为false。

如何在启动GUI的其余部分并正确填充Vector之前阅读文本？

编辑：很抱歉这一切都很模糊。我会发布代码，但它长约337行..

import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.Collections;
import java.util.Scanner;
import java.util.Vector;

import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;

@SuppressWarnings("serial")
public class SteamLibraryGUI extends JFrame implements ActionListener
{
    //For main window
    private JButton exitButton, addEntry, editEntry, removeEntry; 
    private JLabel selectGame, gameCount;
    private JComboBox<String> gameCombo;
    private Vector<Game> gamesList = new Vector<Game>();
    private Vector<String> titleList = new Vector<String>();
    private int numGames = gamesList.size();
    private int selectedGame;

    //For add window
    private JFrame addFrame;
    private JLabel gameTitle = new JLabel("Title:");
    private JTextField titleText = new JTextField(60);
    private JCheckBox singleBox, coopBox, multiBox, cloudBox, controllerBox, achieveBox, pcBox;
    private JButton addGame, addCancel;

    //For edit window
    private JFrame editFrame;
    private JButton editGame, editCancel;

    public SteamLibraryGUI()
    {


        setTitle("Steam Library Organizer");
        addEntry = new JButton("Add a game");
        editEntry = new JButton("Edit a game");
        removeEntry = new JButton("Remove a game");
        exitButton = new JButton("Exit");
        selectGame = new JLabel("Select a game:");
        gameCount = new JLabel("Number of games:"+numGames);
        gameCombo = new JComboBox<String>(titleList);

        JPanel selectPanel = new JPanel();
        selectPanel.setLayout(new GridLayout(1,2));
        selectPanel.add(selectGame);
        selectPanel.add(gameCombo);

        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new GridLayout(1,3));
        buttonPanel.add(addEntry);
        buttonPanel.add(editEntry);
        buttonPanel.add(removeEntry);

        JPanel exitPanel = new JPanel();
        exitPanel.setLayout(new GridLayout(1,2));
        exitPanel.add(gameCount);
        exitPanel.add(exitButton);

        Container pane = getContentPane();
        pane.setLayout(new GridLayout(3,1));
        pane.add(selectPanel);
        pane.add(buttonPanel);
        pane.add(exitPanel);

        addEntry.addActionListener(this);
        editEntry.addActionListener(this);
        removeEntry.addActionListener(this);
        exitButton.addActionListener(this);
        gameCombo.addActionListener(this);
    }

    public void actionPerformed(ActionEvent e)
    {
        if(e.getSource()==addEntry)
            addEntry();
        if(e.getSource()==editEntry)
            editEntry(gamesList.get(selectedGame));
        if(e.getSource()==removeEntry)
        {
            removeEntry(selectedGame);
            update();
        }
        if(e.getSource()==exitButton)
            exitProg();
        if(e.getSource()==gameCombo)
            {
                selectedGame = gameCombo.getSelectedIndex();
            }
        if(e.getSource()==singleBox)
            singleBox.isSelected();
        if(e.getSource()==coopBox)
            coopBox.isSelected();
        if(e.getSource()==multiBox)
            multiBox.isSelected();
        if(e.getSource()==cloudBox)
            cloudBox.isSelected();
        if(e.getSource()==controllerBox)
            controllerBox.isSelected();
        if(e.getSource()==achieveBox)
            achieveBox.isSelected();
        if(e.getSource()==pcBox)
            pcBox.isSelected();
        if(e.getSource()==addGame)
        {
            gamesList.add(new Game(titleText.getText(), singleBox.isSelected(), coopBox.isSelected(), 
                    multiBox.isSelected(), cloudBox.isSelected(), controllerBox.isSelected(), 
                    achieveBox.isSelected(), pcBox.isSelected()));
            titleList.add(titleText.getText());
            addFrame.dispose();
            update();
        }
        if(e.getSource()==addCancel)
            addFrame.dispose();
        if(e.getSource()==editCancel)
            editFrame.dispose();
        if(e.getSource()==editGame)
        {
            gamesList.get(selectedGame).name = titleText.getText();
            gamesList.get(selectedGame).single = singleBox.isSelected();
            gamesList.get(selectedGame).coop = coopBox.isSelected();
            gamesList.get(selectedGame).multi = multiBox.isSelected();
            gamesList.get(selectedGame).cloud = cloudBox.isSelected();
            gamesList.get(selectedGame).controller = controllerBox.isSelected();
            gamesList.get(selectedGame).achieve = achieveBox.isSelected();
            gamesList.get(selectedGame).pc = pcBox.isSelected();
            titleList.remove(selectedGame);
            titleList.add(titleText.getText());
            editFrame.dispose();
            update();
        }
    }

    public void update()
    {
        Collections.sort(titleList);
        Collections.sort(gamesList);
        gameCombo.updateUI();
        titleText.setText("");
        gameCombo.setSelectedIndex(-1);
        numGames = gamesList.size();
        gameCount.setText("Number of games:"+numGames);
    }

    public void addEntry()
    {
        addFrame = new JFrame("Add Entry");
        addFrame.setDefaultCloseOperation(EXIT_ON_CLOSE);
        addFrame.getContentPane();
        addFrame.setLayout(new GridLayout(3,1));

        singleBox = new JCheckBox("Single-Player");
        singleBox.setSelected(false);
        coopBox = new JCheckBox("Coop");
        coopBox.setSelected(false);
        multiBox = new JCheckBox("MultiPlayer");
        multiBox.setSelected(false);
        cloudBox = new JCheckBox("Steam Cloud");
        cloudBox.setSelected(false);
        controllerBox = new JCheckBox("Controller Support");
        controllerBox.setSelected(false);
        achieveBox = new JCheckBox("Achievements");
        achieveBox.setSelected(false);
        pcBox = new JCheckBox("For New PC");
        pcBox.setSelected(false);
        addGame = new JButton("Add game");
        addCancel = new JButton("Cancel");

        JPanel titlePanel = new JPanel();
        titlePanel.setLayout(new FlowLayout());
        titlePanel.add(gameTitle);
        titlePanel.add(titleText);

        JPanel checkPanel = new JPanel();
        checkPanel.setLayout(new FlowLayout());
        checkPanel.add(singleBox);
        checkPanel.add(coopBox);
        checkPanel.add(multiBox);
        checkPanel.add(cloudBox);
        checkPanel.add(controllerBox);
        checkPanel.add(achieveBox);
        checkPanel.add(pcBox);

        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new FlowLayout());
        buttonPanel.add(addGame);
        buttonPanel.add(addCancel);

        addFrame.add(titlePanel);
        addFrame.add(checkPanel);
        addFrame.add(buttonPanel);

        singleBox.addActionListener(this);
        coopBox.addActionListener(this);
        multiBox.addActionListener(this);
        cloudBox.addActionListener(this);
        controllerBox.addActionListener(this);
        achieveBox.addActionListener(this);
        pcBox.addActionListener(this);
        addGame.addActionListener(this);
        addCancel.addActionListener(this);

        addFrame.pack();
        addFrame.setVisible(true);
    }

    public void editEntry(Game g)
    {
        editFrame = new JFrame("Edit Entry");
        editFrame.setDefaultCloseOperation(EXIT_ON_CLOSE);
        editFrame.getContentPane();
        editFrame.setLayout(new GridLayout(3,1));

        singleBox = new JCheckBox("Single-Player");
        singleBox.setSelected(g.single);
        coopBox = new JCheckBox("Coop");
        coopBox.setSelected(g.coop);
        multiBox = new JCheckBox("MultiPlayer");
        multiBox.setSelected(g.multi);
        cloudBox = new JCheckBox("Steam Cloud");
        cloudBox.setSelected(g.cloud);
        controllerBox = new JCheckBox("Controller Support");
        controllerBox.setSelected(g.controller);
        achieveBox = new JCheckBox("Achievements");
        achieveBox.setSelected(g.achieve);
        pcBox = new JCheckBox("For New PC");
        pcBox.setSelected(g.pc);
        editGame = new JButton("Edit game");
        editCancel = new JButton("Cancel");
        titleText.setText(g.name);

        JPanel titlePanel = new JPanel();
        titlePanel.setLayout(new FlowLayout());
        titlePanel.add(gameTitle);
        titlePanel.add(titleText);

        JPanel checkPanel = new JPanel();
        checkPanel.setLayout(new FlowLayout());
        checkPanel.add(singleBox);
        checkPanel.add(coopBox);
        checkPanel.add(multiBox);
        checkPanel.add(cloudBox);
        checkPanel.add(controllerBox);
        checkPanel.add(achieveBox);
        checkPanel.add(pcBox);

        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new FlowLayout());
        buttonPanel.add(editGame);
        buttonPanel.add(editCancel);

        editFrame.add(titlePanel);
        editFrame.add(checkPanel);
        editFrame.add(buttonPanel);

        singleBox.addActionListener(this);
        coopBox.addActionListener(this);
        multiBox.addActionListener(this);
        cloudBox.addActionListener(this);
        controllerBox.addActionListener(this);
        achieveBox.addActionListener(this);
        pcBox.addActionListener(this);
        editGame.addActionListener(this);
        editCancel.addActionListener(this);

        editFrame.pack();
        editFrame.setVisible(true);
    }

    public void removeEntry(int g)
    {
        Object[] options = {"Yes, remove the game", "No, keep the game"};

        int n = JOptionPane.showOptionDialog(null, "Are you sure you want to remove this game from the list?",
                "Remove game?", JOptionPane.YES_NO_OPTION, JOptionPane.WARNING_MESSAGE, null, options, options[1]);
        if (n==0)
        {
            gamesList.remove(g);
            titleList.remove(g);
        }
    }

    public void exitProg()
    {
        try 
        {
            PrintWriter out = new PrintWriter("games.txt");
            out.flush();
            for(int i=0;i<gamesList.size();i++)
            {

                out.print(gamesList.get(i).toString());
            }
            out.close();
        }
        catch (FileNotFoundException e) {}
        System.exit(0);
    }

    public static void main(String[] args)
    {
        SteamLibraryGUI frame = new SteamLibraryGUI();
        frame.pack();
        frame.setSize(600,200);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Scanner in = new Scanner("games.txt");
        while(in.hasNextLine())
        {
            String line = in.nextLine();
            String[] options = line.split("|");
            Game g = new Game(options[0],Boolean.getBoolean(options[1]),
                    Boolean.getBoolean(options[2]),Boolean.getBoolean(options[3]),
                    Boolean.getBoolean(options[4]),Boolean.getBoolean(options[5]),
                    Boolean.getBoolean(options[6]),Boolean.getBoolean(options[7]));
            frame.gamesList.add(g);
            frame.titleList.add(options[0]);
            System.out.println(g.toString());
        }
        in.close();
    }
}

还有一个Game类，但它只是1个字符串，然后是7个布尔值。

Answer 1

代码中有两个重要的错误。首先，使用字符串参数构造Scanner（这意味着扫描程序扫描字符串，而不是字符串命名的文件）。二，管道字符“|”是一个正则表达元字符。这很重要，因为line.split()在正则表达式上分裂。因此，“|”必须逃脱。如果main()函数编写如下（包含调试输出代码以显示每个步骤都正常工作），则public static void main(String[] args) { SteamLibraryGUI frame = new SteamLibraryGUI(); frame.pack(); frame.setSize(600,200); frame.setVisible(true); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); try { Scanner in = new Scanner(new File("games.txt")); while(in.hasNextLine()) { System.out.println("line = "); String line = in.nextLine(); System.out.println(line); String[] options = line.split("\\|"); System.out.println("Options = "); for (String s : options) { System.out.println(s); } Game g = new Game(options[0],Boolean.getBoolean(options[1]), Boolean.getBoolean(options[2]),Boolean.getBoolean(options[3]), Boolean.getBoolean(options[4]),Boolean.getBoolean(options[5]), Boolean.getBoolean(options[6]),Boolean.getBoolean(options[7])); frame.gamesList.add(g); frame.titleList.add(options[0]); System.out.println(g.toString()); } in.close(); } catch (IOException x) { System.err.println(x); } } 函数可以正常工作：

exitProg()

还有一个重要的问题：方法Game在程序完成之前再次写出“games.txt”文件。如果首先错误地读取文件，则会产生问题，因为错误的数据将被写回文件。在测试期间，这意味着即使读取代码已被更正，它仍将读取从先前测试运行中写入的错误数据。

我在这种情况下的偏好是隔离{{1}}类中“game.txt”的所有读写代码（这样可以更容易地验证读写格式是否相同）和在我编写和测试读取代码后，只编写代码将数据写回，这样可以避免这种问题。