Question

我试图让它使用它的toString（）类列出来自arrayList传单的数据，但无论我做什么，我都无法让字符串出现在textArea中然后是JScrollPane。

        if (event.getSource() == jbtList)
        {
        // New textarea
        JTextArea displayStrings = new JTextArea(5, 30);
        // Generate a new JScrollPane and set its viewport to the textarea
        for(int p = 0; p < flyers.size(); p++)
        {
            String flyerList = flyers.get(p).toString() + "\n";
            displayStrings.append(flyerList);
        }
        JScrollPane scroll = new JScrollPane(displayStrings);
        JOptionPane.showMessageDialog(null,scroll);

我的最终类包含传单数组：

import java.util.ArrayList;
import java.util.Iterator;
public class Culminating {

private String FirstName;
private String LastName;
private String PhoneNumber;
private String Adress;
private int Column;
private int Row;
//Initializing the variables

public String getFirstName()
{
    return this.FirstName;
}
public String getLastName()
{
    return this.LastName;
}
public String getPhoneNumber()
{
    return this.PhoneNumber;
}
public String getAdress()
{
    return this.Adress;
}
public int getColumn()
{
    return this.Column;
}
public int getRow()
{
    return this.Row;
}

// Set data to variables and return if needed
public void setFirstName(String FirstName)
{
    this.FirstName = FirstName;
}
public void setLastName(String LastName)
{
    this.LastName = LastName;
}
public void setPhoneNumber(String PhoneNumber)
{
    this.PhoneNumber = PhoneNumber;
}
public void setAdress(String Adress)
{
    this.Adress = Adress;
}

public Culminating(String FirstName, String LastName, String PhoneNumber, String Adress, int Column, int Row)

{  
    this.FirstName = FirstName;
    this.LastName = LastName;
    this.PhoneNumber = PhoneNumber;
    this.Adress = Adress;
    this.Column = Column;
    this.Row = Row;
}



public String toString()
{
    return FirstName + " " + LastName + "   " + " Phone Number: " + PhoneNumber + " Adress: " + Adress;
    //Turn array to string and return
}
}

另一个完整的课程是：

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.Scanner;
import java.util.ArrayList;
import java.util.Iterator;
public class CulminatingPro implements ActionListener
{
    //Create an array of buttons 
    static JButton[][] buttons = new JButton[10][4];
    static JButton jbtList = new JButton("List");
    ArrayList<Culminating> flyers = new ArrayList<Culminating>();
    static JPanel mainPanel = new JPanel();
    static JPanel paneSeats = new JPanel();
    static JPanel paneInfo = new JPanel();
    String fn;
    String ln;
    String pn;
    String adress;
    int column;
    int row;
    int reply;
    int v;
    Object[] options = {"First Name",
                    "Last Name",
                    "Phone Number",
                    "Adress"};
    public static void main(String[] args)
    {
        JFrame frame = new JFrame("Fly By Buddies");
        frame.setSize(900, 900);

        mainPanel.setLayout( new GridLayout(1,2));
        JPanel paneSeats = new JPanel();
        JPanel paneInfo = new JPanel();
        paneSeats.setLayout( new GridLayout(11, 4, 5,5));
        mainPanel.add(paneSeats);
        mainPanel.add(paneInfo);
        frame.setContentPane(mainPanel);

        for (int i = 0; i < buttons.length; i++)
        {
            for(int j = 0; j < buttons[0].length; j++)
            {

                if (j + 1 == 1)
                {
                    buttons[i][j] = new JButton("Seat " + (i + 1) + "A");
                    buttons[i][j].setBackground(Color.GREEN);
                    paneSeats.add(buttons[i][j]);
                    buttons[i][j].addActionListener(new CulminatingPro());
                }
                else if (j + 1 == 2)
                {
                    buttons[i][j] = new JButton("Seat " + (i + 1) + "B");
                    buttons[i][j].setBackground(Color.GREEN);
                    paneSeats.add(buttons[i][j]);
                    buttons[i][j].addActionListener(new CulminatingPro());
                }
                else if (j + 1== 3)
                {
                    buttons[i][j] = new JButton("Seat " + (i + 1) + "C");
                    buttons[i][j].setBackground(Color.GREEN);
                    paneSeats.add(buttons[i][j]);
                    buttons[i][j].addActionListener(new CulminatingPro());
                }
                else if (j + 1== 4)
                {
                    buttons[i][j] = new JButton("Seat " + (i + 1) + "D");
                    buttons[i][j].setBackground(Color.GREEN);
                    paneSeats.add(buttons[i][j]);
                    buttons[i][j].addActionListener(new CulminatingPro());
                }

            }
        }
        jbtList.setPreferredSize(new Dimension(400, 40));
        jbtList.addActionListener(new CulminatingPro());
        paneInfo.add(jbtList, BorderLayout.NORTH);

        frame.setVisible(true);
        frame.toFront();
    }
    public void actionPerformed(ActionEvent event)
    {
        for (int i = 0; i < buttons.length; i++)
        {
            for(int j = 0; j < buttons[0].length; j++)
            {
                if (event.getSource() == buttons[i][j]) 
                {
                    v = 0;
                    for (int k = 0; k < flyers.size();k++)
                    {

                        if((flyers.get(k).getColumn() == (j) && (flyers.get(k).getColumn() == (j))))
                        {
                            if (!flyers.get(k).getFirstName().equals(""))
                            {
                                reply = JOptionPane.showConfirmDialog(null, 
                                 "Would you like to delete the info on the passenger?", "Deletion", JOptionPane.YES_NO_OPTION);
                                if (reply == JOptionPane.YES_OPTION)
                                {
                                    flyers.remove(k);
                                    buttons[i][j].setBackground(Color.GREEN);
                                }
                                else if (reply == JOptionPane.NO_OPTION)
                                {

Answer 1

您的问题是，您为每个按钮定义了一个新的culminatingPro类实例作为动作侦听器。因此，每次单击一个新按钮时，只需修改其最终的Pro对象，然后列表按钮就不会知道其他实例。

重要的是：

//here you are creating for each button its own CulminatingPro instance
//so in clicking it, it will never know about the flying list 
//of the other instances
buttons[i][j].addActionListener(new CulminatingPro());

和

//here the same like before, your print list button have allways an
//empty list, because this instance of culminatingPro is only used
//by this button.
jbtList.addActionListener(new CulminatingPro());

那应该是同样的culminatingpro对象，所以创建一个并使用它（就像在samle代码中一样）。

我有一个简单的代码修改版本，可行。（你不提供整个代码，所以我必须修改它）：

public class CulminatingPro implements ActionListener {
    // Create an array of buttons
    static JButton[][] buttons = new JButton[10][4];
    static JButton jbtList = new JButton("List");
    ArrayList<Culminating> flyers = new ArrayList<Culminating>();
    static JPanel mainPanel = new JPanel();
    static JPanel paneSeats = new JPanel();
    static JPanel paneInfo = new JPanel();
    String fn;
    String ln;
    String pn;
    String adress;
    int column;
    int row;
    int reply;
    int v;
    Object[] options = { "First Name", "Last Name", "Phone Number", "Adress" };
    JFrame frame = new JFrame("Fly By Buddies");

    public CulminatingPro() {
        System.out.println("HERE");
        frame.setSize(900, 900);

        mainPanel.setLayout(new GridLayout(1, 2));
        JPanel paneSeats = new JPanel();
        JPanel paneInfo = new JPanel();
        paneSeats.setLayout(new GridLayout(11, 4, 5, 5));
        mainPanel.add(paneSeats);
        mainPanel.add(paneInfo);
        frame.setContentPane(mainPanel);

        for (int i = 0; i < buttons.length; i++) {
            for (int j = 0; j < buttons[0].length; j++) {

                if (j + 1 == 1) {
                    buttons[i][j] = new JButton("Seat " + (i + 1) + "A");
                    buttons[i][j].setBackground(Color.GREEN);
                    paneSeats.add(buttons[i][j]);
                    buttons[i][j].addActionListener(this);
                } else if (j + 1 == 2) {
                    buttons[i][j] = new JButton("Seat " + (i + 1) + "B");
                    buttons[i][j].setBackground(Color.GREEN);
                    paneSeats.add(buttons[i][j]);
                    buttons[i][j].addActionListener(this);
                } else if (j + 1 == 3) {
                    buttons[i][j] = new JButton("Seat " + (i + 1) + "C");
                    buttons[i][j].setBackground(Color.GREEN);
                    paneSeats.add(buttons[i][j]);
                    buttons[i][j].addActionListener(this);
                } else if (j + 1 == 4) {
                    buttons[i][j] = new JButton("Seat " + (i + 1) + "D");
                    buttons[i][j].setBackground(Color.GREEN);
                    paneSeats.add(buttons[i][j]);
                    buttons[i][j].addActionListener(this);
                }

            }
        }
        jbtList.setPreferredSize(new Dimension(400, 40));
        jbtList.addActionListener(this);
        paneInfo.add(jbtList, BorderLayout.NORTH);

        frame.setVisible(true);
        frame.toFront();
    }

    public void actionPerformed(ActionEvent event) {
        if (event.getSource() == jbtList) {
            // New textarea
            JTextArea displayStrings = new JTextArea(5, 30);
            // Generate a new JScrollPane and set its viewport to the textarea
            System.out.println(flyers.size());
            for (int p = 0; p < flyers.size(); p++) {
                String flyerList = flyers.get(p).toString() + "\n";
                displayStrings.append(flyerList);
            }
            JScrollPane scroll = new JScrollPane(displayStrings);
            JOptionPane.showMessageDialog(null, scroll);
            return;
        }

        Point pos = getPos(event.getSource());

        // is seat free?
        boolean free = true;
        for (int i = 0; i < flyers.size(); i++) {
            if (flyers.get(i).getColumn() == pos.x
                    && flyers.get(i).getRow() == pos.y) {
                free = false;
                if (!flyers.get(i).getFirstName().equals("")) {
                    reply = JOptionPane
                            .showConfirmDialog(
                                    null,
                                    "Would you like to delete the info on the passenger?",
                                    "Deletion", JOptionPane.YES_NO_OPTION);
                    if (reply == JOptionPane.YES_OPTION) {
                        flyers.remove(i);
                        buttons[pos.x][pos.y].setBackground(Color.GREEN);
                    }
                }
            }
        }

        if (free) {
            flyers.add(new Culminating("Test1", "1Tset", "00000", "test",
                    pos.x, pos.y));
            System.out.println("Add culmination: " + flyers.size());

            buttons[pos.x][pos.y].setBackground(Color.RED);
        }
    }

    public Point getPos(Object object) {
        for (int i = 0; i < buttons.length; i++) {
            for (int j = 0; j < buttons[i].length; j++) {
                if (object == buttons[i][j]) {
                    return new Point(i, j);
                }
            }
        }
        return new Point(-1, -1);
    }

    public static void main(String[] args) {
        new CulminatingPro();
    }
}

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1 个答案: