如何将特定数据字段从 ArrayList 加载到某些 JTextFields？
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【中文标题】如何将特定数据字段从 ArrayList 加载到某些 JTextFields？【英文标题】：How to load specific fields of data from an ArrayList to certain JTextFields? 【发布时间】：2021-11-16 07:51:34 【问题描述】：我正在处理一项要求我们将数据从 .csv 文件加载到 ArrayList 的任务。 .csv 文件的第一列包含船名，必须放在JComboBox 中。当用户从JComboBox点击特定的船时，该船的相应信息将显示在JTextFields中。这是我们在方法名称itemStateChanged 中给出的算法：
-
从下拉列表的选项中提取船名。
为存储完整数据的船舶列表中的每艘船舶重复。
如果船名与所选船名相同
用船舶信息填写所有文本字段
退出重复
如果结束
结束重复
到目前为止，我已经能够将数据从 .csv 文件加载到 ArrayList。我也能够完成算法的第 1 步。我不知道如何为每艘船重复此操作（步骤 2）。我也不知道如何用所选船的相应数据填写文本字段。
这是我对JTextFields 的实例化：
public class ShipGUI extends JFrame
private int win_width = 650;
private int win_Height = 240;
private int gridRows = 3;
private int gridCols = 2;
JComboBox SelectShipBox;
JTextField nameText = new JTextField();
JTextField flagText = new JTextField();
JTextField yearText = new JTextField();
JTextField beamText = new JTextField();
JTextField draftText = new JTextField();
JTextField lengthText = new JTextField();
到目前为止，这是我的 itemStateChanged 方法的代码：
SelectShipBox = new JComboBox();
SelectShipBox.addItemListener(new ItemListener()
public void itemStateChanged(ItemEvent ie)
String select = (String)ie.getItem();
);
String[] templist = "Green Acres Afloat","Supnik","Her Majesty's Glory","Sulaco",
"Nostromos", "Flying Dutchmen", "Enterprize", "Black Peral",
"PT109", "Titanic", "IronSides", "Nautilus","El Vaquero","Machu
Picchu Skiff", "Folgers Best";
SelectShipBox.setModel(new javax.swing.DefaultComboBoxModel<>(templist));
在这篇文章中附上了一张最终输出应该是什么样子的图片。
编辑
这是 .csv 文件包含的数据：
Supnik,Russia,1911,64,16,38
Her Majesty's Glory,UK,1945,117,29,68
Sulaco,USA,1975,45,11,31
Nostromos,USA,1914,194,49,101
Flying Dutchmen,Tortuga,1912,69,17,36
Enterprize,USSF,1997,125,31,65
Black Peral,Barbados,1925,196,49,106
PT109,USN,1933,151,38,77
Titanic,UK,1995,188,47,97
IronSides,USA,1907,126,32,69
Nautilus,no flag,1886,127,32,68
El Vaquero,Argentina,1986,91,23,51
Machu Picchu Skiff,Peru,2004,135,34,76
Folgers Best,Columbia,1959,197,49,108
【问题讨论】：
是的，对应的信息来自.csv文件。能否请您告诉我如何在 itemStateChanged 方法中检查事件是否为 SELECT 事件？ Edit 您的问题并发布包含名为 Sulaco 的船舶数据的 CSV 文件中的行。另外，我建议您访问此网页：docs.oracle.com/javase/tutorial/uiswing/index.html 我已编辑并发布了 .csv 文件包含的所有内容。我会检查页面。 【参考方案1】：首先，您需要一个类来存储一艘船的数据。
public class ShipInfo
private String shipName;
private String countryOfRegistration;
private int yearOfConstruction;
private int lengthAtWaterline;
private int draftAtWaterline;
private int beamAtWaterline;
public ShipInfo(String name,
String country,
int year,
int length,
int draft,
int beam)
setShipName(name);
setCountryOfRegistration(country);
setYearOfConstruction(year);
setLengthAtWaterline(length);
setDraftAtWaterline(draft);
setBeamAtWaterline(beam);
public String getShipName()
return shipName;
public String getCountryOfRegistration()
return countryOfRegistration;
public int getYearOfConstruction()
return yearOfConstruction;
public int getLengthAtWaterline()
return lengthAtWaterline;
public int getDraftAtWaterline()
return draftAtWaterline;
public int getBeamAtWaterline()
return beamAtWaterline;
public void setShipName(String name)
if (name != null && !name.isEmpty())
shipName = name;
else
throw new IllegalArgumentException("Null or empty ship name.");
public void setCountryOfRegistration(String country)
if (country != null && !country.isEmpty())
countryOfRegistration = country;
else
throw new IllegalArgumentException("Null or empty country of registration.");
public void setYearOfConstruction(int year)
if (year > 0)
yearOfConstruction = year;
else
throw new IllegalArgumentException("Negative year of construction.");
public void setLengthAtWaterline(int length)
if (length > 0)
lengthAtWaterline = length;
else
throw new IllegalArgumentException("Negative length at waterline.");
public void setDraftAtWaterline(int draft)
if (draft > 0)
draftAtWaterline = draft;
else
throw new IllegalArgumentException("Negative draft at waterline.");
public void setBeamAtWaterline(int beam)
if (beam > 0)
beamAtWaterline = beam;
else
throw new IllegalArgumentException("Negative beam at waterline.");
public boolean equals(Object obj)
boolean isEqual = false;
if (obj instanceof ShipInfo)
ShipInfo otherShip = (ShipInfo) obj;
isEqual = shipName.equals(otherShip.shipName) &&
countryOfRegistration.equals(otherShip.countryOfRegistration) &&
yearOfConstruction == otherShip.yearOfConstruction;
return isEqual;
public int hashCode()
return shipName.hashCode() + countryOfRegistration.hashCode() + yearOfConstruction;
public String toString()
return shipName;
ShipInfo 类为每个单独的数据包含一个数据成员。 equals 和 hashCode 方法对于您的 GUI 应用程序来说并不是真正必需的，但是 toString 方法是因为 JComboBox 调用该方法来显示其项目列表以及所选项目。因此方法toString 只返回船名。
这是 GUI 应用程序代码。 （代码后的注释。）
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import javax.swing.BorderFactory;
import javax.swing.DefaultComboBoxModel;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class ShipsGui implements ActionListener, ItemListener
private static final String ADD_SHIP = "Add Ship";
private static final String CLEAR = "Clear";
private static final String QUIT = "Quit";
private JComboBox<ShipInfo> shipsCombo;
private JFrame frame;
JTextField beamText;
JTextField draftText;
JTextField flagText;
JTextField lengthText;
JTextField nameText;
JTextField yearText;
@Override // java.awt.event.ActionListener
public void actionPerformed(ActionEvent actionEvent)
String actionCommand = actionEvent.getActionCommand();
switch (actionCommand)
case ADD_SHIP:
JOptionPane.showMessageDialog(frame,
"Not yet implemented.",
actionCommand,
JOptionPane.INFORMATION_MESSAGE);
break;
case CLEAR:
clearAll();
break;
case QUIT:
System.exit(0);
default:
JOptionPane.showMessageDialog(frame,
actionCommand,
"Unhandled",
JOptionPane.WARNING_MESSAGE);
@Override // java.awt.event.ItemListener
public void itemStateChanged(ItemEvent itemEvent)
if (itemEvent.getStateChange() == ItemEvent.SELECTED)
Object obj = itemEvent.getItem();
if (obj instanceof ShipInfo)
ShipInfo shipInfo = (ShipInfo) obj;
nameText.setText(shipInfo.getShipName());
flagText.setText(shipInfo.getCountryOfRegistration());
beamText.setText(getIntText(shipInfo.getBeamAtWaterline()));
draftText.setText(getIntText(shipInfo.getDraftAtWaterline()));
lengthText.setText(getIntText(shipInfo.getLengthAtWaterline()));
yearText.setText(getIntText(shipInfo.getYearOfConstruction()));
private void addColumnSpacer(JPanel form, GridBagConstraints gbc)
addLabelToForm(form, " ", gbc);
private void addLabelToForm(JPanel form, String text, GridBagConstraints gbc)
JLabel label = new JLabel(text);
int anchor = gbc.anchor;
gbc.anchor = GridBagConstraints.LINE_END;
form.add(label, gbc);
gbc.anchor = anchor;
private void clearAll()
shipsCombo.setSelectedIndex(-1);
beamText.setText("");
draftText.setText("");
flagText.setText("");
lengthText.setText("");
nameText.setText("");
yearText.setText("");
private void createAndDisplayGui() throws IOException
frame = new JFrame("Shipping News");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(createHeader(), BorderLayout.PAGE_START);
frame.add(createForm(), BorderLayout.CENTER);
frame.add(createButtonsPanel(), BorderLayout.PAGE_END);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
shipsCombo.setSelectedIndex(0);
private JButton createButton(String text)
JButton button = new JButton(text);
button.addActionListener(this);
return button;
private JPanel createButtonsPanel()
JPanel buttonsPanel = new JPanel();
buttonsPanel.add(createButton(CLEAR));
buttonsPanel.add(createButton(QUIT));
buttonsPanel.add(createButton(ADD_SHIP));
return buttonsPanel;
private JPanel createForm()
JPanel form = new JPanel(new GridBagLayout());
form.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
GridBagConstraints gbc = new GridBagConstraints();
// Initialize 'GridBagConstraints'.
gbc.gridx = 0;
gbc.gridy = 0;
gbc.insets.bottom = 2;
gbc.insets.left = 2;
gbc.insets.right = 2;
gbc.insets.top = 2;
// First row.
addLabelToForm(form, "Ship Name:", gbc);
nameText = getTextField();
gbc.gridx = 1;
form.add(nameText, gbc);
gbc.gridx = 2;
addColumnSpacer(form, gbc);
gbc.gridx = 3;
addLabelToForm(form, "Length at waterline:", gbc);
lengthText = getTextField();
gbc.gridx = 4;
form.add(lengthText, gbc);
// Second row.
gbc.gridx = 0;
gbc.gridy = 1;
addLabelToForm(form, "Country of Registration:", gbc);
flagText = getTextField();
gbc.gridx = 1;
form.add(flagText, gbc);
gbc.gridx = 2;
addColumnSpacer(form, gbc);
gbc.gridx = 3;
addLabelToForm(form, "Draft at waterline:", gbc);
draftText = getTextField();
gbc.gridx = 4;
form.add(draftText, gbc);
// Third row.
gbc.gridx = 0;
gbc.gridy = 2;
addLabelToForm(form, "Year of Construction:", gbc);
yearText = getTextField();
gbc.gridx = 1;
form.add(yearText, gbc);
gbc.gridx = 2;
addColumnSpacer(form, gbc);
gbc.gridx = 3;
addLabelToForm(form, "Beam at waterline:", gbc);
beamText = getTextField();
gbc.gridx = 4;
form.add(beamText, gbc);
return form;
private JPanel createHeader() throws IOException
JPanel header = new JPanel();
Icon ico = new ImageIcon(getClass().getResource("ship.png"));
JLabel label = new JLabel("Select a ship", ico, SwingConstants.CENTER);
header.add(label);
DefaultComboBoxModel<ShipInfo> model = new DefaultComboBoxModel<>(getShips());
shipsCombo = new JComboBox<>(model);
shipsCombo.setSelectedIndex(-1); // No initial selection.
shipsCombo.addItemListener(this);
header.add(shipsCombo);
return header;
private String getIntText(int anInt)
return String.valueOf(anInt);
private JTextField getTextField()
JTextField textField = new JTextField(15);
textField.setHorizontalAlignment(JTextField.CENTER);
return textField;
private ShipInfo[] getShips() throws IOException
List<ShipInfo> lst = new ArrayList<>();
try (FileReader fr = new FileReader("shipinfo.csv");
BufferedReader br = new BufferedReader(fr))
String line = br.readLine();
while (line != null)
String[] flds = line.split(",");
ShipInfo shipInfo = new ShipInfo(flds[0],
flds[1],
Integer.parseInt(flds[2]),
Integer.parseInt(flds[3]),
Integer.parseInt(flds[4]),
Integer.parseInt(flds[5]));
lst.add(shipInfo);
line = br.readLine();
public static void main(String[] args)
String slaf = UIManager.getSystemLookAndFeelClassName();
try
UIManager.setLookAndFeel(slaf);
catch (ClassNotFoundException |
IllegalAccessException |
InstantiationException |
UnsupportedLookAndFeelException x)
x.printStackTrace();
final ShipsGui gui = new ShipsGui();
EventQueue.invokeLater(() ->
try
gui.createAndDisplayGui();
catch (IOException xIo)
throw new RuntimeException(xIo);
);
shipsCombo 显示ShipInfo 对象的列表。该列表是从 CSV 文件中获取的。方法getShips 逐行读取文件。 ShipInfo 对象是根据文件单行中的数据创建的。创建一个包含所有ShipInfo 对象的数组，并且该数组用于为shipsCombo 创建模型。注意getShips方法使用try-with-resources。
[content pane 的]JFrame 的默认layout manager 是BorderLayout。顶部组件是shipsCombo 和JLabel。 JLabel 包含文本和图标。中心组件是所有JTextFields，在shipsCombo中显示所选船的详细信息。在底部组件中是JButtons。
请注意，我从以下 *** 问题的答案中获得了将 JTextField 中的文本居中的代码：
How do I center a JTextfield
当shipsCombo中的选中项改变时，方法itemStateChanged被调用。所选项目是类ShipInfo 的一个实例。从所选项目中提取详细信息并显示在相应的JTextFields 中。
当任何一个JButtons 被点击时，方法actionPerformed 被调用。我不想猜测 Add Ship 按钮应该做什么，所以上面的代码只是显示一条消息，说明按钮操作尚未实现。
这是在我的装有 JDK 17 的 Windows 10 计算机上运行的应用程序的屏幕截图。
【讨论】：
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