问题：
删除行后未更新JTable
蒙化
我正在尝试更新JTable（或data？）的行在我对一行执行删除操作后，当选择另一行时，可以编辑所选行。当前删除该行将使已删除行下方的行上移，但如果选择了该行号并尝试进行编辑，则会返回（JOptionPane），就像未选择任何内容一样。它似乎没有“刷新”数据（？）。
这是一个SCCE，希望有人可以运行它并指出问题。我试着尽可能地缩小它，以便于复制/粘贴：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.plaf.nimbus.NimbusLookAndFeel;
import javax.swing.table.*;
import java.util.*;
public class JTableTest4 extends JFrame implements ActionListener {
private JPanel dbOutputPanel = new JPanel();
private JTable dbOutputTable;
private JScrollPane dbOutputTableSP = new JScrollPane(dbOutputTable);
private JButton deleteButton = new JButton("Delete");
private JButton editButton = new JButton("Edit");
private JButton searchButton = new JButton("Search");
private JPanel south = new JPanel();
protected HashMap<Integer, Student> studentMap;
protected int studentIndex;
public JTableTest4() {
super("Student Database");
populateMap();
south.add(deleteButton);
south.add(editButton);
south.add(searchButton);
dbOutputTable = new JTable();
dbOutputTable.setFillsViewportHeight(true);
dbOutputTable.setPreferredScrollableViewportSize(new Dimension(450, 250));
dbOutputTableSP = new JScrollPane(dbOutputTable);
dbOutputPanel.add(dbOutputTableSP);
searchButton.addActionListener(this);
editButton.addActionListener(this);
deleteButton.addActionListener(this);
this.add(new JLabel("Welcome to " + getTitle(), JLabel.CENTER), BorderLayout.NORTH);
this.add(dbOutputPanel, BorderLayout.CENTER);
this.add(south, BorderLayout.SOUTH);
this.setSize(600, 500);
this.setResizable(false);
this.setLocationRelativeTo(null);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setVisible(true);
}
@Override
public void actionPerformed(ActionEvent event) {
Object source = event.getSource();
int selectedRow = dbOutputTable.getSelectedRow();
if (source == searchButton) {
displayTable();
} else if (source == editButton) {
Student student = studentMap.get(selectedRow);
displayTable();
if (student != null) {
System.out.println("\n" + student.toString() + "\n");
} else {
JOptionPane.showMessageDialog(this, "Please select a student to edit",
getTitle(), JOptionPane.INFORMATION_MESSAGE);
}
}
else if (source == deleteButton) {
System.out.println("Row count: " + ((DefaultTableModel) dbOutputTable.getModel()).getRowCount());
System.out.println("Selected Row: " + (selectedRow));
String[] options = {"Yes", "No"};
int result = JOptionPane.showOptionDialog(null, "Delete student from database?",
"Delete Student", JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE,
null, options, options[1]);
if (result == JOptionPane.YES_OPTION) {
studentMap.remove(selectedRow);
((DefaultTableModel) dbOutputTable.getModel()).fireTableRowsDeleted(selectedRow, selectedRow);//not the issue
displayTable();
} else if (result == JOptionPane.NO_OPTION) {
}
}
displayTable();
}
public void populateMap() {
studentMap = new HashMap<>();
Student s1 = new Student("232", "john", "thomas", 22);
Student s2 = new Student("56", "bob", "doe", 23);
Student s3 = new Student("678", "sally", "smith", 24);
Student s4 = new Student("32", "chris", "johnson", 21);
Student s5 = new Student("12", "dsfg", "sgfsdg", 22);
studentMap.put(0, s1);
studentMap.put(1, s2);
studentMap.put(2, s3);
studentMap.put(3, s4);
studentMap.put(4, s5);
}
public TableModel toTableModel() {
System.out.println("Using toTableModel");
ArrayList<Student> studentList = new ArrayList<>();
for (Integer key : studentMap.keySet()) {
Student newStudent = (Student) studentMap.get(key);
studentList.add(newStudent);
}
DefaultTableModel tmodel = new DefaultTableModel(
new Object[]{"Id", "First", "Last", "Age"}, 0);
for (int i = 0; i < studentList.size(); i++) {
Student newStudent = studentList.get(i);
tmodel.addRow(new Object[] {newStudent.getStudentId(),
newStudent.getStudentFirstName(),
newStudent.getStudentLastName(),
newStudent.getStudentAge()});
}
return tmodel;
}
public void displayTable() {
dbOutputTable.setModel(toTableModel());
// dbOutputTable.revalidate();
}
public static void main(String[] args) throws Exception {
JTableTest4 test = new JTableTest4();
UIManager.setLookAndFeel(new NimbusLookAndFeel());
}
}
class Student {
private String studentId;
private String studentFirstName;
private String studentLastName;
private int studentAge;
public Student(String id, String first, String last, int age) {
this.studentId = id;
this.studentFirstName = first;
this.studentLastName = last;
this.studentAge = age;
}
public String getStudentId() {return studentId;}
public void setStudentId(String studentId) {this.studentId = studentId;}
public String getStudentFirstName() {return studentFirstName;}
public void setStudentFirstName(String studentFirstName) {this.studentFirstName = studentFirstName;}
public String getStudentLastName() {return studentLastName;}
public void setStudentLastName(String studentLastName) {this.studentLastName = studentLastName;}
public int getStudentAge() {return studentAge;}
public void setStudentAge(int studentAge) {this.studentAge = studentAge;}
@Override
public String toString() {
String st = "_id : " + this.studentId + "\n";
st += "First Name : " + this.studentFirstName + "\n";
st += "Last Name : " + this.studentLastName + "\n";
st += "Age : " + this.studentAge + "\n";
return st;
}
}
我在这里看到这个问题的各种形式都有一些不同，通常都是相同的建议，我也尝试了一些。如果您能提供任何帮助，我们将不胜感激。谢谢
共有1个答案
程招
您的“数据模型”和表模型需要保持更紧密的同步。您的displayTable方法令人担忧，它表明您对模型、视图和数据应该如何管理的基本错误理解。
就我个人而言，我会使用一个更好地将现有的学生列表与表格模型结合起来的抽象表，而不是使用两个不同的模型，但这可能超出了问题的范围。
下面是您的代码的略微修改版本，它使用DefaultTableModel#removeow更新JTable
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.HashMap;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.UIManager;
import javax.swing.plaf.nimbus.NimbusLookAndFeel;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableModel;
public class JTableTest4 extends JFrame implements ActionListener {
private JPanel dbOutputPanel = new JPanel();
private JTable dbOutputTable;
private JScrollPane dbOutputTableSP = new JScrollPane(dbOutputTable);
private JButton deleteButton = new JButton("Delete");
private JButton editButton = new JButton("Edit");
private JButton searchButton = new JButton("Search");
private JPanel south = new JPanel();
protected HashMap<Integer, Student> studentMap;
protected int studentIndex;
public JTableTest4() {
super("Student Database");
populateMap();
south.add(deleteButton);
south.add(editButton);
south.add(searchButton);
dbOutputTable = new JTable();
dbOutputTable.setModel(toTableModel());
dbOutputTable.setFillsViewportHeight(true);
dbOutputTable.setPreferredScrollableViewportSize(new Dimension(450, 250));
dbOutputTableSP = new JScrollPane(dbOutputTable);
dbOutputPanel.add(dbOutputTableSP);
searchButton.addActionListener(this);
editButton.addActionListener(this);
deleteButton.addActionListener(this);
this.add(new JLabel("Welcome to " + getTitle(), JLabel.CENTER), BorderLayout.NORTH);
this.add(dbOutputPanel, BorderLayout.CENTER);
this.add(south, BorderLayout.SOUTH);
this.setSize(600, 500);
this.setResizable(false);
this.setLocationRelativeTo(null);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setVisible(true);
}
@Override
public void actionPerformed(ActionEvent event) {
Object source = event.getSource();
int selectedRow = dbOutputTable.getSelectedRow();
if (source == searchButton) {
//displayTable();
} else if (source == editButton) {
Student student = studentMap.get(selectedRow);
//displayTable();
if (student != null) {
System.out.println("\n" + student.toString() + "\n");
} else {
JOptionPane.showMessageDialog(this, "Please select a student to edit",
getTitle(), JOptionPane.INFORMATION_MESSAGE);
}
} else if (source == deleteButton) {
System.out.println("Row count: " + ((DefaultTableModel) dbOutputTable.getModel()).getRowCount());
System.out.println("Selected Row: " + (selectedRow));
String[] options = {"Yes", "No"};
int result = JOptionPane.showOptionDialog(null, "Delete student from database?",
"Delete Student", JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE,
null, options, options[1]);
if (result == JOptionPane.YES_OPTION) {
studentMap.remove(selectedRow);
((DefaultTableModel)dbOutputTable.getModel()).removeRow(selectedRow);
// ((DefaultTableModel) dbOutputTable.getModel()).fireTableRowsDeleted(selectedRow, selectedRow);//not the issue
// displayTable();
} else if (result == JOptionPane.NO_OPTION) {
}
}
//displayTable();
}
public void populateMap() {
studentMap = new HashMap<>();
Student s1 = new Student("232", "john", "thomas", 22);
Student s2 = new Student("56", "bob", "doe", 23);
Student s3 = new Student("678", "sally", "smith", 24);
Student s4 = new Student("32", "chris", "johnson", 21);
Student s5 = new Student("12", "dsfg", "sgfsdg", 22);
studentMap.put(0, s1);
studentMap.put(1, s2);
studentMap.put(2, s3);
studentMap.put(3, s4);
studentMap.put(4, s5);
}
public TableModel toTableModel() {
System.out.println("Using toTableModel");
ArrayList<Student> studentList = new ArrayList<>();
for (Integer key : studentMap.keySet()) {
Student newStudent = (Student) studentMap.get(key);
studentList.add(newStudent);
}
DefaultTableModel tmodel = new DefaultTableModel(
new Object[]{"Id", "First", "Last", "Age"}, 0);
for (int i = 0; i < studentList.size(); i++) {
Student newStudent = studentList.get(i);
tmodel.addRow(new Object[]{newStudent.getStudentId(),
newStudent.getStudentFirstName(),
newStudent.getStudentLastName(),
newStudent.getStudentAge()});
}
return tmodel;
}
public void displayTable() {
dbOutputTable.setModel(toTableModel());
// dbOutputTable.revalidate();
}
public static void main(String[] args) throws Exception {
JTableTest4 test = new JTableTest4();
UIManager.setLookAndFeel(new NimbusLookAndFeel());
}
}
class Student {
private String studentId;
private String studentFirstName;
private String studentLastName;
private int studentAge;
public Student(String id, String first, String last, int age) {
this.studentId = id;
this.studentFirstName = first;
this.studentLastName = last;
this.studentAge = age;
}
public String getStudentId() {
return studentId;
}
public void setStudentId(String studentId) {
this.studentId = studentId;
}
public String getStudentFirstName() {
return studentFirstName;
}
public void setStudentFirstName(String studentFirstName) {
this.studentFirstName = studentFirstName;
}
public String getStudentLastName() {
return studentLastName;
}
public void setStudentLastName(String studentLastName) {
this.studentLastName = studentLastName;
}
public int getStudentAge() {
return studentAge;
}
public void setStudentAge(int studentAge) {
this.studentAge = studentAge;
}
@Override
public String toString() {
String st = "_id : " + this.studentId + "\n";
st += "First Name : " + this.studentFirstName + "\n";
st += "Last Name : " + this.studentLastName + "\n";
st += "Age : " + this.studentAge + "\n";
return st;
}
}
此示例使用了一个自定义的表模型（名为StudentTableModel），它将表模型包装在基础数据模型周围，并协调更新。
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.UIManager;
import javax.swing.plaf.nimbus.NimbusLookAndFeel;
import javax.swing.table.AbstractTableModel;
public class JTableTest4 extends JFrame implements ActionListener {
private JPanel dbOutputPanel = new JPanel();
private JTable dbOutputTable;
private JScrollPane dbOutputTableSP = new JScrollPane(dbOutputTable);
private JButton deleteButton = new JButton("Delete");
private JButton editButton = new JButton("Edit");
private JButton searchButton = new JButton("Search");
private JPanel south = new JPanel();
public JTableTest4() {
super("Student Database");
south.add(deleteButton);
south.add(editButton);
south.add(searchButton);
dbOutputTable = new JTable();
dbOutputTable.setModel(makeModel());
dbOutputTable.setFillsViewportHeight(true);
dbOutputTable.setPreferredScrollableViewportSize(new Dimension(450, 250));
dbOutputTableSP = new JScrollPane(dbOutputTable);
dbOutputPanel.add(dbOutputTableSP);
searchButton.addActionListener(this);
editButton.addActionListener(this);
deleteButton.addActionListener(this);
this.add(new JLabel("Welcome to " + getTitle(), JLabel.CENTER), BorderLayout.NORTH);
this.add(dbOutputPanel, BorderLayout.CENTER);
this.add(south, BorderLayout.SOUTH);
this.setSize(600, 500);
this.setResizable(false);
this.setLocationRelativeTo(null);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setVisible(true);
}
@Override
public void actionPerformed(ActionEvent event) {
Object source = event.getSource();
int selectedRow = dbOutputTable.convertRowIndexToModel(dbOutputTable.getSelectedRow());
if (selectedRow < 0) {
return;
}
if (source == searchButton) {
//displayTable();
} else if (source == editButton) {
// Student student = studentMap.get(selectedRow);
// //displayTable();
// if (student != null) {
// System.out.println("\n" + student.toString() + "\n");
// } else {
// JOptionPane.showMessageDialog(this, "Please select a student to edit",
// getTitle(), JOptionPane.INFORMATION_MESSAGE);
// }
} else if (source == deleteButton) {
StudentTableModel model = (StudentTableModel)dbOutputTable.getModel();
model.removeRow(selectedRow);
// System.out.println("Row count: " + ((DefaultTableModel) dbOutputTable.getModel()).getRowCount());
// System.out.println("Selected Row: " + (selectedRow));
// String[] options = {"Yes", "No"};
// int result = JOptionPane.showOptionDialog(null, "Delete student from database?",
// "Delete Student", JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE,
// null, options, options[1]);
// if (result == JOptionPane.YES_OPTION) {
// studentMap.remove(selectedRow);
// ((DefaultTableModel) dbOutputTable.getModel()).removeRow(selectedRow);
// // ((DefaultTableModel) dbOutputTable.getModel()).fireTableRowsDeleted(selectedRow, selectedRow);//not the issue
// // displayTable();
// } else if (result == JOptionPane.NO_OPTION) {
// }
}
//displayTable();
}
public StudentTableModel makeModel() {
System.out.println("Using toTableModel");
ArrayList<Student> studentList = new ArrayList<>();
studentList.add(new Student("232", "john", "thomas", 22));
studentList.add(new Student("56", "bob", "doe", 23));
studentList.add(new Student("678", "sally", "smith", 24));
studentList.add(new Student("32", "chris", "johnson", 21));
studentList.add(new Student("12", "dsfg", "sgfsdg", 22));
return new StudentTableModel(studentList);
}
public static void main(String[] args) throws Exception {
JTableTest4 test = new JTableTest4();
UIManager.setLookAndFeel(new NimbusLookAndFeel());
}
class Student {
private String studentId;
private String studentFirstName;
private String studentLastName;
private int studentAge;
public Student(String id, String first, String last, int age) {
this.studentId = id;
this.studentFirstName = first;
this.studentLastName = last;
this.studentAge = age;
}
public String getStudentId() {
return studentId;
}
public void setStudentId(String studentId) {
this.studentId = studentId;
}
public String getStudentFirstName() {
return studentFirstName;
}
public void setStudentFirstName(String studentFirstName) {
this.studentFirstName = studentFirstName;
}
public String getStudentLastName() {
return studentLastName;
}
public void setStudentLastName(String studentLastName) {
this.studentLastName = studentLastName;
}
public int getStudentAge() {
return studentAge;
}
public void setStudentAge(int studentAge) {
this.studentAge = studentAge;
}
@Override
public String toString() {
String st = "_id : " + this.studentId + "\n";
st += "First Name : " + this.studentFirstName + "\n";
st += "Last Name : " + this.studentLastName + "\n";
st += "Age : " + this.studentAge + "\n";
return st;
}
}
class StudentTableModel extends AbstractTableModel {
List<Student> studentList;
public StudentTableModel(List<Student> studentList) {
this.studentList = studentList;
}
@Override
public int getRowCount() {
return studentList.size();
}
@Override
public int getColumnCount() {
return 4;
}
@Override
public String getColumnName(int column) {
switch (column) {
case 0: return "ID";
case 1: return "First Name";
case 2: return "Last Name";
case 3: return "Age";
}
return "??";
}
@Override
public Object getValueAt(int rowIndex, int columnIndex) {
Student student = studentList.get(rowIndex);
switch (columnIndex) {
case 0: return student.studentId;
case 1: return student.studentFirstName;
case 2: return student.studentLastName;
case 3: return student.studentAge;
}
return null;
}
// This is a more advance topic then I want to get into here
@Override
public boolean isCellEditable(int rowIndex, int columnIndex) {
return false;
}
public Student studentAt(int row) {
return studentList.get(row);
}
public void removeRow(int index) {
studentList.remove(index);
fireTableRowsDeleted(index, index);
}
}
}
详细了解如何使用表
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