刪除或插入后更新JTable

Question

我有一個JTable，它是由Access DB使用ResultSet和AbstractTableModel填充的。 我有一種方法可以從數據庫中正確刪除記錄，但是在刷新表模型的當前視圖時遇到了麻煩。 我看過類似的文章，並嘗試使用fireTableRowsDeleted和fireTableDataChanged但沒有運氣。 我還注意到其他帖子提到了DefaultTableModel的使用，因為它具有添加/刪除行方法的功能，但是我正在使用的代碼來自我去年使用的Java教科書（教授從未達到這一點，所以我想自己學習一下） ）...

這是自定義JFrame的類：

 class AdministrationFrame extends JFrame { //set variable for location of database private static final File DB_FILE = new File("C:\\\\Eclipse\\\\EmpInOutBoard - TEMP.accdb"); //database URL private static final String DB_URL = "jdbc:ucanaccess://" + DB_FILE.getAbsolutePath(); //set default query to retrieve all users sorted by last name private static final String DEFAULT_QUERY = "SELECT EmployeeNo, FirstName, LastName, DisplayName, GroupName, CompanyName " + "FROM Employees " + "WHERE DisabledState = false " + "ORDER BY LastName"; //layout for window private final BorderLayout layout; //administration window private final JFrame adminFrame; private final JPanel tablePanel; private final JPanel tablePanel2; private final JPanel buttonPanel; //items for tablePanel private final JLabel filterLabel; private final JTextField filterTextField; private final JButton filterButton; //items for buttonPanel private final JButton updateButton; private final JButton deleteButton; private String employeeID; private Connection conn; private JTable resultTable; private static ResultSetTableModel tblModel; public AdministrationFrame() { layout = new BorderLayout(10, 10); setLayout(layout); //place GUI components on JFrame's content pane adminFrame = new JFrame("Employee Modification Panel"); //set up JPanels tablePanel = new JPanel(); tablePanel2 = new JPanel(); String tablePanelTitle = "Employee Details"; tablePanel.setBorder(BorderFactory.createTitledBorder(null, tablePanelTitle, TitledBorder.CENTER, TitledBorder.TOP, new Font("Arial", Font.BOLD + Font.ITALIC, 22), Color.BLACK)); tablePanel2.setLayout(new BoxLayout(tablePanel2, BoxLayout.Y_AXIS)); buttonPanel = new JPanel(); //set up items in each JPanel filterLabel = new JLabel("Filter:"); filterLabel.setAlignmentX(LEFT_ALIGNMENT); filterTextField = new JTextField(); filterTextField.setAlignmentX(LEFT_ALIGNMENT); filterButton = new JButton("Apply Filter"); filterButton.setAlignmentX(LEFT_ALIGNMENT); updateButton = new JButton("Add/Update"); deleteButton = new JButton("Delete"); //create ResultSetTableModel and display database table try { //create TableModel for results of the default query tblModel = new ResultSetTableModel(DB_URL, DEFAULT_QUERY); //create JTable based on the tblModel resultTable = new JTable(tblModel) { @Override public Dimension getPreferredScrollableViewportSize() { return new Dimension(600, 250); } }; resultTable.setAutoResizeMode(JTable.AUTO_RESIZE_ALL_COLUMNS); resultTable.getTableHeader().setResizingAllowed(false); //disable column resizing resultTable.getTableHeader().setReorderingAllowed(false); //disable column dragging resultTable.setSelectionMode(ListSelectionModel.SINGLE_SELECTION); //sets table to only allow selection of single row resultTable.getSelectionModel().addListSelectionListener(new RowListener()); //register event handlers final JScrollPane tablePane = new JScrollPane(resultTable); //add items to JPanels tablePanel2.add(filterLabel); tablePanel2.add(Box.createRigidArea(new Dimension(0, 2))); tablePanel2.add(filterTextField); tablePanel2.add(Box.createRigidArea(new Dimension(0, 10))); tablePanel2.add(filterButton); tablePanel.add(tablePane); tablePanel.add(tablePanel2); buttonPanel.add(updateButton); buttonPanel.add(deleteButton); //add JPanels to frame adminFrame.add(tablePanel, BorderLayout.NORTH); adminFrame.add(buttonPanel, BorderLayout.SOUTH); final TableRowSorter<TableModel> sorter = new TableRowSorter<TableModel>(tblModel); resultTable.setRowSorter(sorter); //create listener for filterButton filterButton.addActionListener(new ActionListener() { //pass filter text to Listener public void actionPerformed(ActionEvent e) { String text = filterTextField.getText(); if (text.length() == 0) sorter.setRowFilter(null); else { try { //make filter case-insensitive sorter.setRowFilter(RowFilter.regexFilter("(?i)" + text)); } catch (PatternSyntaxException pse) { JOptionPane.showMessageDialog(null, "Bad regex pattern", "Bad regex pattern", JOptionPane.ERROR_MESSAGE); } } } }); deleteButton.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { if(employeeID != null && !employeeID.isEmpty()) { try { deleteFromTable(employeeID); JOptionPane.showMessageDialog(null, "User " + employeeID + " deleted from the table", "Successful Deletion", JOptionPane.PLAIN_MESSAGE); //tblModel.fireTableRowsDeleted(resultTable.getSelectedRow(), resultTable.getSelectedRow()); } catch (SQLException e1) { e1.printStackTrace(); } } else { JOptionPane.showMessageDialog(null, "No user selected. Cannot perform delete.", "ERROR", JOptionPane.ERROR_MESSAGE); } } }); pack(); //dispose of window when user quits application //(do not want to close application) adminFrame.setDefaultCloseOperation(DISPOSE_ON_CLOSE); adminFrame.setSize(800, 400); adminFrame.setVisible(true); adminFrame.setLocationRelativeTo(null); adminFrame.setResizable(false); //ensure database is closed when user quits application adminFrame.addWindowListener(new WindowAdapter() { //disconnect from database and exit when window has closed public void windowClosed(WindowEvent event) { tblModel.disconnectFromDatabase(); System.exit(0); } }); } catch (SQLException sqlException) { JOptionPane.showMessageDialog(null, sqlException.getMessage(), "Database error", JOptionPane.ERROR_MESSAGE); tblModel.disconnectFromDatabase(); System.exit(1); //terminate application } } private class RowListener implements ListSelectionListener { @Override public void valueChanged(ListSelectionEvent event) { if(!event.getValueIsAdjusting()) { int row = resultTable.getSelectedRow(); if(row == -1) //no row found JOptionPane.showMessageDialog(adminFrame, "Selected row not found in filtered set", null, JOptionPane.WARNING_MESSAGE); else { employeeID = resultTable.getValueAt(row, resultTable.getColumn("EmployeeNo").getModelIndex()).toString(); } } } }; //updates DB to delete selected user/record from the table public void deleteFromTable(String empID) throws SQLException { PreparedStatement prepStmnt = null; String deleteSQL = "DELETE " + "FROM Employees " + "WHERE EmployeeNo = ?"; try { conn = DriverManager.getConnection(DB_URL); conn.setAutoCommit(false); prepStmnt = conn.prepareStatement(deleteSQL); prepStmnt.setString(1, empID); prepStmnt.executeUpdate(); conn.commit(); } catch (SQLException sqlExcep) { sqlExcep.printStackTrace(); if(conn != null) { try { System.err.print("Rolling back transaction"); conn.rollback(); } catch (SQLException excep) { excep.printStackTrace(); } } System.exit(1); //terminate application } finally //close the connection { if(prepStmnt != null) prepStmnt.close(); conn.setAutoCommit(true); conn.close(); } } }//end class EmpInOutBoard 

這是AbstractTableModel的類（從我的課本中稍作修改）：

 class ResultSetTableModel extends AbstractTableModel { private final Connection connection; private final Statement statement; private ResultSet resultSet; private ResultSetMetaData resultSetMetaData; private int numRowCount; //track DB connection status private boolean dbConnStatus = false; //constructor initializes rSet and obtains its //metadata object; also determines number of rows public ResultSetTableModel(String url, String query) throws SQLException { //connect to the database connection = DriverManager.getConnection(url); //create statement to query database statement = connection.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE); //update database connection status dbConnStatus = true; //set query and execute it setQuery(query); } //get class that represents column type @SuppressWarnings({ "unchecked", "rawtypes" }) public Class getColumnClass(int column) throws IllegalStateException { //ensure database connection is available if(!dbConnStatus) throw new IllegalStateException("No connection to the Database"); //determine Java class of column try { String className = resultSetMetaData.getColumnClassName(column + 1); //return Class object that represents class Name return Class.forName(className); } catch (Exception e) { e.printStackTrace(); } return Object.class; //if problems occur above, assume type Object } //remove row in the ResultSet public void removeRow(int row) { // try // { // resultSet.absolute(row); // resultSet.deleteRow(); // } // catch (SQLException e) // { // e.printStackTrace(); // } // fireTableRowsDeleted(row, row); } //get the number of columns in the ResultSet public int getColumnCount() throws IllegalStateException { //ensure database connection is available if(!dbConnStatus) throw new IllegalStateException("No connection to the Database"); //determine number of columns try { return resultSetMetaData.getColumnCount(); } catch (SQLException sqlException) { sqlException.printStackTrace(); } return 0; //if problem occur above, return 0 for number of columns } //get name of a particular column in ResultSet public String getColumnName(int column) throws IllegalStateException { //ensure database connection is available if(!dbConnStatus) throw new IllegalStateException("No connection to the Database"); //determine column name try { return resultSetMetaData.getColumnName(column + 1); } catch (SQLException sqlException) { sqlException.printStackTrace(); } return ""; //if problems occur above, return empty string for column name } //return number of rows in ResultSet public int getRowCount() throws IllegalStateException { //ensure database connection is available if(!dbConnStatus) throw new IllegalStateException("No connection to the Database"); return numRowCount; } //obtain value in particular row and column public Object getValueAt(int row, int column) throws IllegalStateException { //ensure database connection is available if(!dbConnStatus) throw new IllegalStateException("No connection to the Database"); //obtain a value at specified ResultSet row and column try { resultSet.absolute(row + 1); return resultSet.getObject(column + 1); } catch (SQLException sqlException) { sqlException.printStackTrace(); } return ""; //if problems occur above, return empty string object } //set new database query string public void setQuery(String query) throws SQLException, IllegalStateException { //ensure database connection is available if(!dbConnStatus) throw new IllegalStateException("No connection to the Database"); //specify query and execute it resultSet = statement.executeQuery(query); //obtain metadata for ResultSet resultSetMetaData = resultSet.getMetaData(); //determine number of rows in ResultSet resultSet.last(); //move to last row numRowCount = resultSet.getRow(); //get row number //notify JTable that model has changed fireTableStructureChanged(); } //close Statement and Connection public void disconnectFromDatabase() { //ensure database connection is available if(dbConnStatus); //determine number of columns try { resultSet.close(); statement.close(); connection.close(); } catch (SQLException sqlException) { sqlException.printStackTrace(); } finally { dbConnStatus = false; } } } //end class ResultSetTableModel 

如您所見，我嘗試在第二個類中添加removeRow方法，但最終出現錯誤： attempt to assign to non-updatable column 。 我缺少什么來刷新我的表模型？ 我願意將其更改為使用DefaultTableModel及其內置方法，如果這樣做更容易/更簡單。 謝謝

Answer 1

我沒有使用直接行索引，因為如果用戶按任一列對數據進行排序，則該行索引可能會更改。 我覺得，由於employeeID是唯一的，因此最好在此進行匹配：

 //remove row in the ResultSet public void removeRow(String empID) { int rsRow = 0; try { //set cursor to beginning of data set (before first row) if(!resultSet.isBeforeFirst()) resultSet.beforeFirst(); //iterate through resultSet to find matching record with //correct employee ID. once found delete row while(resultSet.next()) { if(resultSet.getString("EmployeeNo") == empID) { rsRow = resultSet.getRow(); resultSet.deleteRow(); System.out.println("User: " + empID + " was deleted from row: " + rsRow); break; } } resultSet.last(); numRowCount = resultSet.getRow(); fireTableRowsDeleted(rsRow, rsRow); // resultSet.absolute(rsRow); // resultSet.deleteRow(); } catch (SQLException e) { e.printStackTrace(); } } 

當然，現在JTable中的數據正在消失，我不明白。