java - 无法将文件中的数据读取到 JComboBox

Question

我正在尝试制作一个用户界面，在其中我将文件从文本文件读取到 JComboBoxes 并显示结果为 JTextFields。只有第一个组合框从文件中更新，而其余部分未从文件中更新。

这是我的代码:

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

public class Main1 extends JPanel 
{
  public Main1() {
JPanel buttonPanel = new JPanel();
add(buttonPanel);
buttonPanel.setLayout(new GridLayout(0, 4, 5, 5));


JTextField field1 = new JTextField(5);
field1.setEditable(false);
buttonPanel.add(field1);
JTextField field2 = new JTextField(5);
field2.setEditable(false);
buttonPanel.add(field2);
JTextField field3 = new JTextField(5);
field3.setEditable(false);
buttonPanel.add(field3);
JTextField field4 = new JTextField(5);
field4.setEditable(false);
buttonPanel.add(field4);

JComboBox comboBox = new JComboBox();
comboBox.setEditable(true);

 comboBox.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent event) {

            JComboBox comboBox = (JComboBox) event.getSource();

            field1.setText((String) comboBox.getSelectedItem());

        }
    });

JComboBox comboBox1 = new JComboBox();
comboBox1.addItem("1");
    comboBox1.addItem("2");
comboBox1.addItem("4");


 comboBox1.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent event) {

            JComboBox comboBox1 = (JComboBox) event.getSource();

            Object selected = comboBox1.getSelectedItem();
            if(selected.toString().equals("1"))
            field2.setText("3");
            else if(selected.toString().equals("2"))
                field2.setText("6");
    else if(selected.toString().equals("4"))
        field2.setText("12");


        }
     });
JComboBox comboBox2 = new JComboBox();
comboBox2.addItem("1");
    comboBox2.addItem("2");
comboBox2.addItem("4");

 comboBox2.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent event) {

            JComboBox comboBox2 = (JComboBox) event.getSource();

            Object selected = comboBox2.getSelectedItem();
            if(selected.toString().equals("1"))
            field3.setText("1");
            else if(selected.toString().equals("2"))
                field3.setText("2");
    else if(selected.toString().equals("4"))
        field3.setText("4");


        }
    });
JComboBox comboBox3 = new JComboBox();
comboBox3.addItem("1");
    comboBox3.addItem("2");

 comboBox3.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent event) {

            JComboBox comboBox3 = (JComboBox) event.getSource();

            Object selected = comboBox3.getSelectedItem();
            if(selected.toString().equals("1"))
            field4.setText("1");
            else if(selected.toString().equals("2"))
                field4.setText("2");
        }
    });

buttonPanel.add(comboBox);
buttonPanel.add(comboBox1);
buttonPanel.add(comboBox2);
buttonPanel.add(comboBox3);

try{
        InputStream ips=new FileInputStream("test.txt"); 
        InputStreamReader ipsr=new InputStreamReader(ips);
        BufferedReader br=new BufferedReader(ipsr);
        String line;
        while ((line=br.readLine())!=null) {
    String[] s = line.split(" ");
    comboBox.setSelectedItem(s[0]);
    comboBox1.setSelectedItem(s[1]);
    comboBox2.setSelectedItem(s[2]);
    comboBox3.setSelectedItem(s[3]);
        }
        br.close(); 
    }       
    catch (Exception e){
        e.printStackTrace();
    }


  }
  public static void main(String[] args) {
 Main1 a = new Main1();
 JFrame f = new JFrame();
 f.getContentPane().add(a);
 f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 f.pack();
 f.setVisible(true);
  }
 }

文本文件:

14 54 89 56

Answer 1

文件列表中的任何值都不包含在组合框列表中，因此除了第一个值之外，不会出现任何值。发生这种情况是因为这是唯一可编辑的。来自 docs

If anObject is not in the list and the combo box is uneditable, it will not change the current selection

只需在应用程序启动时将所有预期项目添加到组合框模型中即可。