问题描述
我正在尝试在行上执行删除之后更新jtable（或数据？）的行，因此选择另一行时，可以编辑所选行。当前删除该行会将已删除行下方的行向上移动，但如果选择了该行号并尝试进行编辑，它将返回 (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。我试图尽可能地缩小它以方便复制/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.@R_595_4045@ION_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;
}
}
我在这里看到过各种形式的这个问题，但都有些不同，通常是相同的建议，我尝试了一些。您能提供的任何帮助将不胜感激。谢谢！
解决方法
您的“数据模型”和 TableModel 需要保持同步。您的 displayTable 方法令人担忧，表明您对模型、视图和数据的管理方式存在基本误解。
就我个人而言，我会使用 AbstractTable 更好地将现有的 studentList 与 TableModel 结合，而不是使用两种不同的模型，但这可能超出了问题的范围。
以下是您的代码的略微修改版本，它使用 DefaultTableModel#removeRow 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;
}
}
更“高级”的实现
此示例使用自定义 TableModel（名为 StudentTableModel），它将 TableModel 包裹在基本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(450,500);
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,// 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",// null,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",22));
studentList.add(new Student("56",23));
studentList.add(new Student("678",24));
studentList.add(new Student("32",21));
studentList.add(new Student("12",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,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);
}
}
}
仔细查看How to Use Tables了解更多详情