java - 如何正确从文件加载 JFrame？

Question

我正在为我的计算机科学类(class)制作这个成绩保持程序，而我还没有开始工作的一件事是保存/加载 session 。正如我现在设置的那样，它会在您退出时自动保存，并在启动时自动加载(如果有文件要加载)。但是，我觉得我加载或保存它不正确；有一个主 JFrame 保存所有数据，这就是保存的一个对象。当它加载后，向您展示会更容易。

If it looks like this when I close it: :

然后it'll look like this when I start it up again:

此外，当程序加载 JFrame 时，“Enter Student”按钮以及用于输入的 JTextField 上的 ActionListener 也会停止工作。该程序分为 3 个类文件:

成绩簿:

import javax.swing.*;
import java.awt.event.*;
import java.io.*;

public class GradeBook implements java.io.Serializable {
    private static JFrame frame;
    public static void main(String[] args) throws Exception{
        try{
            FileInputStream fis = new FileInputStream("t.tmp");
            ObjectInputStream ois = new ObjectInputStream(fis);

            frame = (JFrame) ois.readObject();

            ois.close();
        } catch(Throwable t) {
            frame = new JFrame("Course Grades");
        }

        frame.addWindowListener(new closing());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(new CourseGrade());
        frame.pack();
        frame.setVisible(true);
    }

结束:

    private static class closing extends WindowAdapter {
        public void windowClosing(WindowEvent e) {
            try {
                FileOutputStream fos = new FileOutputStream("t.tmp");
                ObjectOutputStream oos = new ObjectOutputStream(fos);

                oos.writeObject(frame);

                oos.close();
            } catch(Throwable t){System.out.println(t.getMessage());}
        }
    }
}

类(class)成绩:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.FlowLayout;
import java.util.Random;
import javax.swing.table.*;
import java.io.*;
public class CourseGrade extends JPanel implements java.io.Serializable {
    private JLabel entername;
    private JTextField in;
    private JTextArea list;
    private JScrollPane scroll;
    private String[] students = new String[1000];
    private JButton enter;
    private JButton[] studentbuttons = new JButton[1000];
    private JButton[] delete=new JButton[1000];
    private int numstudents;
    private JFrame[] studentframes=new JFrame[1000];
    private static JTable[] tables=new JTable[1000];
    private static DefaultTableModel[] model=new DefaultTableModel[1000];
    private static int[] numass=new int[1000];
    public CourseGrade() {
        String[][] data = {{"", "", "", ""}};
        String[] headers = {"Assignment", "Date Assigned", "Score", "Percentage"};
        for(int i=0; i<tables.length; i++){
            model[i] = new DefaultTableModel(data, headers);
            tables[i] = new JTable(model[i]){
                public boolean isCellEditable(int rowIndex, int colIndex) {
                    return false;
                }
            };
        }
        numstudents=0;
        in=new JTextField(13);
        in.addActionListener(new enterListener());
        list=new JTextArea();
        scroll=new JScrollPane(list);
        list.setEditable(false);
        entername=new JLabel("Enter a student's name");
        enter=new JButton("Enter Student");
        enter.addActionListener(new enterListener());
        setPreferredSize(new Dimension(260, 300));
        setBackground(Color.green);

        add(entername);
        add(in);
        add(enter);
        add(scroll);

        scroll.setPreferredSize(new Dimension(240, 200));
    }

    private class enterListener implements ActionListener {
        public void actionPerformed(ActionEvent event) {
            String x=in.getText();
            String y="";
            String z="";
            in.setText("");
            int a=numstudents+1;
            if(x.length()>0) x=a+". " + x + "\n";
            students[numstudents] = x;
            if(x.length()>0)numstudents++;
            for(int i=0; i<numstudents; i++){
                x=students[i];
                if(x.length()>13)x=x.substring(0,11)+"...\n";
                y+=x;
            }
            studentbuttons[numstudents]=new JButton("Edit");
            studentbuttons[numstudents].addActionListener(new grades());
            delete[numstudents]=new JButton("Delete");
            delete[numstudents].addActionListener(new del());
            list.setText(y);
            list.add(studentbuttons[numstudents]);
            studentbuttons[numstudents].setBounds(100,(numstudents-1)*16,55,15);
            list.add(delete[numstudents]);
            delete[numstudents].setBounds(160,(numstudents-1)*16,70,15);
        }
    }

    private class grades implements ActionListener {
        public void actionPerformed(ActionEvent event) {
            Object obj = event.getSource();
            if(obj instanceof JButton){
                JButton clicked = (JButton)obj;
                int x=clicked.getY()/16;
                String y=students[x];
                for(int i=0; i<y.length(); i++){
                    String q=y.substring(i,i+1);
                    if(q.equals(" ")) { 
                        y=y.substring(i+1);
                        i=y.length()+1;
                    }
                }
                studentframes[x]=new JFrame(y+"'s Grades");
                studentframes[x].setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                try{studentframes[x].getContentPane().add(new GradePage(x, tables[x], numass[x]));}
                catch(Exception e){}
                studentframes[x].pack();
                studentframes[x].setVisible(true);
            }
        }
    }

    private class del implements ActionListener {
        public void actionPerformed(ActionEvent event) {
            Object obj = event.getSource();
            if(obj instanceof JButton){
                JButton clicked = (JButton)obj;
                int x=clicked.getY()/16;
                String y="", z="";
                studentbuttons[numstudents].setVisible(false);
                delete[numstudents].setVisible(false);
                numstudents--;
                int q=3;
                int w=0;
                for(int i=x; i<=numstudents; i++){
                    if(i<10)q=1;
                    else if(i<100) q=2;
                    tables[i]=tables[i+1];
                    numass[i]=numass[i+1];
                    model[i]=model[i+1];
                    w=i+1;
                    try{if(!students[i+1].equals(null)){students[i]=w+students[i+1].substring(q);} else{students[i]=null;}}catch(Throwable t){}
                }
                for(int i=0; i<numstudents; i++){
                    y=students[i];
                    if(y.length()>13)y=y.substring(0,11)+"...\n";
                    z+=y;
                }
                list.setText(z);
            }
        }
    }
    public static void setTable(int numtable, JTable table){
        tables[numtable]=table;
    }
    public static void newRow(int numtable){
        model[numtable].addRow(new Object[]{"", "", "", ""});
    }
    public static void setNumEntries(int numtable, int num){
        numass[numtable]=num;
    }
}

第三堂课应该与此无关，所以我现在不会发布它。

我意识到代码可能写得不好，但我才高中计算机科学二年级，我们实际上还没有涵盖任何内容。这个程序甚至不应该是一个 GUI，这是我第一次听说输入或输出流，所以我真的对它们一无所知。我现在意识到让类实现 java.io.Serialized 可能是不必要的，但是当我尝试研究这个问题时，我遇到了有人在讨论某些对象如何无法保存，因为它们自然不会实现它。如果这是一些愚蠢的错误，我们深表歉意，并感谢您的宝贵时间。

Answer 1

您可以将数据存储在这样的记事本文件中

            try
            {
                FileWriter file = new FileWriter( "insert file name here" );
                BufferedWriter buffer = new BufferedWriter( file ) ;
                buffer.write( "insert file content here" ) ;
                buffer.newLine();
                buffer.close();
            }
            catch ( IOException e )
            {
                //Insert error message here
            }

然后像这样阅读

    try
    {
        FileReader file = new FileReader( "insert file name here" ) ;

        BufferedReader buffer = new BufferedReader( file );

        String line = "" ;

        while( ( line = buffer.readLine() ) != null )
        {
            System.out.println( line ) ;
        }

        buffer.close() ;
    }
    catch( IOException e )
    {
        //Insert error message here
    }

希望有帮助