Java 试图向另一个类中的GUI显示hashmap值

问题是： 我想查看我所有的客户名单。因此，我将使用哈希映射并输出它们的ic num和名称。如果我尝试使用终端，输出运行正常

但现在我想将这些散列映射的结果输出到GUI中

这是我到目前为止的编码。您可以跳过viewNumCust的“操作权限”事件。这就是我试图将haspmap输出到jtextarea的地方

import javax.swing.*;
import java.io.*;
import java.util.*;

import java.awt.*;
import java.awt.event.*;
import java.io.FileReader;
import java.util.HashMap;
import java.util.Scanner;
import java.util.StringTokenizer;

public class manageClientAccGui extends JFrame
{
ImageIcon image;
JLabel imgLabel,clientLabel,helloLabel,greetingLabel;
JButton createCustProfileButt,editClientAccButt,deleteClientButt,backClientButt,viewNumCust;
JPanel panel1,panel2,panel3,panel4,panel5,panel6,panel7;
JTextArea viewListCust;

public manageClientAccGui()
{

    super("Team Garoking Manage Customer");

    Container con = getContentPane();
    con.setLayout(new BorderLayout());

    image = new ImageIcon("images/garokingLogo.jpg");
    imgLabel = new JLabel(image);

    clientLabel = new JLabel("Manage Client Account");
    clientLabel.setForeground(Color.WHITE);

    helloLabel = new JLabel("Hello! ");
    helloLabel.setForeground(Color.WHITE);

    greetingLabel = new JLabel("What would you like to do? ");
    greetingLabel.setForeground(Color.WHITE);

    JScrollPane scrollPane = new JScrollPane(viewListCust,
            JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
            JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
    scrollPane.setPreferredSize(new Dimension(100, 100));

    JLabel empty = new JLabel("");
    JLabel empty1 = new JLabel("");
    JLabel empty2 = new JLabel("");
    JLabel empty3 = new JLabel("");
    JLabel empty4 = new JLabel("");

    createCustProfileButt = new JButton("Create Customer");
    editClientAccButt = new JButton("Edit Customer Details");
    deleteClientButt = new JButton("Remove Customer");
    viewNumCust = new JButton("View Number of Customers");
    backClientButt = new JButton("Back");
    viewListCust = new JTextArea();
    viewListCust.setEditable(false);

    panel1 = new JPanel();
    panel2 = new JPanel(new GridLayout(12,3));
    panel3 = new JPanel(new GridLayout(12,3,0,3));
    panel4 = new JPanel();
    panel5 = new JPanel();

    panel6 = new JPanel(new GridLayout(1,2));
    panel7 = new JPanel(new GridLayout(1,2));

    panel1.add(imgLabel);
    panel1.setBackground(new Color(90,18,18));

    panel2.add(clientLabel);
    panel2.add(empty);
    panel2.add(createCustProfileButt);
    panel2.add(empty1);
    panel2.add(editClientAccButt);
    panel2.add(empty2);
    panel2.add(deleteClientButt);
    panel2.add(empty3);
    panel2.add(viewNumCust);    
    panel2.add(empty4);
    panel2.add(backClientButt);
    panel2.setBackground(new Color(90,18,18));

    panel6.add(helloLabel);
    panel6.setBackground(new Color(90,18,18));

    panel7.add(greetingLabel);
    panel7.setBackground(new Color(90,18,18));

    panel3.add(panel6);
    panel3.add(panel7);
    panel3.setBackground(new Color(90,18,18));
    panel3.add(scrollPane);

    panel5.add(panel3);
    panel5.setBackground(new Color(90,18,18));

    panel4.add(panel2);
    panel4.setBackground(new Color(90,18,18));

    con.add(panel4, BorderLayout.WEST);
    con.add(panel1, BorderLayout.NORTH);
    con.add(panel5, BorderLayout.CENTER);

    Action act = new Action();

    createCustProfileButt.addActionListener(act);
    editClientAccButt.addActionListener(act);
    deleteClientButt.addActionListener(act);
    backClientButt.addActionListener(act);
    viewNumCust.addActionListener(act);

    setVisible(true);
    Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
    setLocation(((dim.width-1024)/2), ((dim.height-650)/2));
    setSize(1024,650);

}

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

class Action implements ActionListener
    {
        public void actionPerformed(ActionEvent e)
        {   
            if(e.getSource() == createCustProfileButt)
            {
                dispose();
                new Log("Accessing create customer");
                new addCustGui();
            }

            if(e.getSource() == editClientAccButt)
            {
                dispose();
                new Log("Accessing edit customer");
                new editCustGui();
            }

            if(e.getSource() == deleteClientButt)
            {
                dispose();
                new Log("Accessing remove customer");
                new removeCustGui();
            }

            if(e.getSource() == backClientButt)
            {
                dispose();
                new Log("Accessing main menu");
                new menuGarokingGui();
            }

            if(e.getSource() == viewNumCust)
            {
                int enumer = 0;
                HashMap<String, String> map = new HashMap<String, String>();

                try
                {
                    Scanner scanner = new Scanner(new FileReader("IndividualDetails.txt"));

                    while (scanner.hasNextLine()) {
                        String[] columns = scanner.nextLine().split("\t");
                        map.put(columns[1,], columns[2])
                        enumer++;
                    }
                }catch (FileNotFoundException ex)
                    {
                    }
                    new Log("View latest");
                    viewListCust.append("The clients are : " + map.values());
                    viewListCust.append("The total number of clients are : " + enumer);         
            }
        }
    }
}

Mapvalues返回对象的集合

调用viewListCust.appendThe Client are:+map.values只需调用返回集合的CollectiontoString方法，该方法不可能提供内容的漂亮视图

相反，您必须自己迭代集合

viewListCust.append("The clients are :");
for (String value : map.values()) {
    viewListCust.append("\n" + value);
}

现在请记住，当您读取文件并附加内容时，您正在阻止事件调度线程，这将使您的程序看起来好像挂起了

您可能希望在更新UI之前利用SwingWorker在后台加载文件。签出

在将viewListCust传递给JScrollPane之前，您需要实例化它，如下所示：

---

当您将viewListCust传递到JScrollPane构造函数时，它当前为空。

1将}catch FileNotFoundException ex{}更改为}catch FileNotFoundException ex{ex.printStackTrace；}并报告输出。2潜在的长时间运行任务，如文件I/O，不应在EDT中完成。相反，对于长时间运行的任务，使用SwingWorker。请参阅更多细节。还考虑JTALE，如图所示。谢谢安得烈和TrasVald。我目前正在学习printstacktrace，我对GUI还比较陌生。作为记录，我的客户名单不会增长那么多，但我知道你的意思。目前正在研究swingworker@SalehinSuhaimi如果某个答案解决了您的问题，请确保将其标记为已接受：我是GUI新手，所以我现在就来看看swingworker。但在此之前，我尝试了ur编码，它说我看不到“字符串值：map.values”行中的map.values{'它说AbstractMap.values字段不可见？您需要在new LogView latest下替换两行；在action performed方法中…我确实在日志下替换了它。我得到了错误。可能默认情况下这些值是私有的？抱歉，我的错误，键入错误。for循环应该为字符串value:map.values读取{.Updated Answer非常感谢。它现在运行得很好。我确实实例化了它，代码只是乱七八糟：或者我错过了什么？你在创建JScrollPane后实例化了它。你需要在之前完成它。换句话说，只需复制你的viewListCust代码，然后按照我显示的顺序粘贴到创建滚动窗格的地方。啊，我忘了它一定很整齐。非常感谢

viewListCust = new JTextArea();
viewListCust.setEditable(false);

JScrollPane scrollPane = new JScrollPane(viewListCust,
                    JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
                    JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
scrollPane.setPreferredSize(new Dimension(100, 100));