JTable: Detect cell data change

Question

In Netbeans, I used the GUI Builder to insert a JTable into my application.

I have just one class (CustomerDB) so far which is:

package CustomerDB;  import [...];  public class CustomerDB extends javax.swing.JFrame {      CellEditorListener ChangeNotification = new CellEditorListener() {         public void editingCanceled(ChangeEvent e) {             System.out.println("The user canceled editing.");         }          public void editingStopped(ChangeEvent e) {             System.out.println("The user stopped editing successfully.");         }     };      public CustomerDB() {         customerTable = new javax.swing.JTable();         customerTable.setModel(new javax.swing.table.DefaultTableModel(             new Object [][] {                 {null, null, null, null},                 {null, null, null, null},                 {null, null, null, null},                 {null, null, null, null},                 {null, null, null, null},                 {null, null, null, null},                 {null, null, null, null},                 {null, null, null, null},                 {null, null, null, null},                 {null, null, null, null}             },             new String [] {                 "ID", "Name", "Address", "Phone"             }         ) {             Class[] types = new Class [] {                 java.lang.String.class, java.lang.String.class, java.lang.String.class, java.lang.String.class             };              public Class getColumnClass(int columnIndex) {                 return types [columnIndex];             }         });         customerTable.getDefaultEditor(String.class).addCellEditorListener(ChangeNotification);     }       public static void main(String args[]) {         java.awt.EventQueue.invokeLater(new Runnable() {             public void run() {                 new CustomerDB().setVisible(true);             }         });     }      // Variables declaration - do not modify     [...]     private javax.swing.JTable customerTable;     [...]     // End of variables declaration  } 

Whenever a user changes data in the table, I want to get the old value (optional) and the new value of that cell.

In order to get this data, I tried to implement an event listener:

    CellEditorListener ChangeNotification = new CellEditorListener() {         public void editingCanceled(ChangeEvent e) {             System.out.println("The user canceled editing.");         }          public void editingStopped(ChangeEvent e) {             System.out.println("The user stopped editing successfully.");         }     }; 

Then I assign this CellEditorListener to the table (its cell editor):

    customerTable.getDefaultEditor(String.class).addCellEditorListener(ChangeNotification); 

This works so far. But it doesn't yet enable me to detect the old and the new value of this cell. What else do I have to do?

Thank you very much in advance!

Answer 1

But it doesn't yet enable me to detect the old and the new value of this cell. What else do I have to do?

It is easier to use a TableModelListener to listen for changes but it still has the problem of not being able to access the old value.

Check out the Table Cell Listener for a solution that gives you access to the "old value" as well as the "new value".

Answer 2

or TableModelLister with ListSelectionListener, fist returns if TableCell changed, second from selected call, then just compare Row & Column Index from TableModelLister with ListSelectionListener

import java.awt.*; import java.util.Random; import java.util.Vector; import javax.swing.*; import javax.swing.event.ListSelectionEvent; import javax.swing.event.ListSelectionListener; import javax.swing.event.TableModelEvent; import javax.swing.event.TableModelListener; import javax.swing.table.AbstractTableModel; import javax.swing.table.TableCellRenderer;  public class Forum implements ListSelectionListener {      private JFrame frame = new JFrame("Frame");     private JPanel fatherCenter = new JPanel();     private JScrollPane tableScroll = new JScrollPane();     private myTableModel tableModel;     private JTable dialogTable;     private ListSelectionModel lsDialog;      private void addComponentsToPane(Container pane) {         tableModel = new myTableModel();         dialogTable = new JTable(tableModel) {              private static final long serialVersionUID = 1L;              @Override             public Component prepareRenderer(TableCellRenderer renderer, int row, int column) {                 Component comp = super.prepareRenderer(renderer, row, column);                 JComponent jc = (JComponent) comp;//for Custom JComponent                 if (!isRowSelected(row)) {                     int modelRow = convertRowIndexToModel(row);                     boolean type = (Boolean) getModel().getValueAt(modelRow, 2);                     boolean type1 = (Boolean) getModel().getValueAt(modelRow, 3);                     boolean type2 = (Boolean) getModel().isCellEditable(row, column);                     comp.setForeground(Color.black);                     if ((type) && (!type1)) {                         comp.setBackground(Color.yellow);                     } else if ((!type) && (type1)) {                         comp.setBackground(Color.orange);                     } else if ((!type) || (!type1)) {                         comp.setBackground(Color.red);                         //} else if ((!type2)) {                         //comp.setForeground(Color.red);                         //comp.setBackground(Color.magenta);                     } else {                         comp.setBackground(row % 2 == 0 ? getBackground() : getBackground().darker());                     }                     dialogTable.convertRowIndexToView(0);                 } else {                     comp.setForeground(Color.blue);                     comp.setBackground(Color.lightGray);                 }                 if (!isCellEditable(row, column)) {                     comp.setForeground(Color.red);                     comp.setBackground(Color.magenta);                 }                 return comp;             }         };         tableScroll = new JScrollPane(dialogTable, ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,                 ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);         tableScroll.setBorder(null);         dialogTable.getTableHeader().setReorderingAllowed(false);         dialogTable.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);         lsDialog = dialogTable.getSelectionModel();         dialogTable.putClientProperty("terminateEditOnFocusLost", Boolean.TRUE);         dialogTable.setRowHeight(20);         dialogTable.setRowMargin(2);         ListSelectionModel rowSelMod = dialogTable.getSelectionModel();         //ListSelectionModel colSelMod = dialogTable.getColumnModel().getSelectionModel();         rowSelMod.addListSelectionListener(this);         //colSelMod.addListSelectionListener(this);         fatherCenter = new JPanel();         fatherCenter.setLayout(new BorderLayout(10, 10));         fatherCenter.add(tableScroll, BorderLayout.CENTER);         pane.add(fatherCenter);     }      private void addData() {         Runnable doRun1 = new Runnable() {              @Override             public void run() {                 tableModel.resetTable();                 Vector<String> tbl = new Vector<String>();                 Vector<Object> tbl1 = new Vector<Object>();                 Random rnd = new Random();                 tbl.add("Integer");                 tbl.add("Double");                 tbl.add("Boolean");                 tbl.add("Boolean");                 tbl.add("String");                 tableModel.setColumnNames(tbl);                 for (int row = 0; row < 30; row++) {                     tbl1 = null;                     tbl1 = new Vector<Object>();                     tbl1.addElement(row + 1);                     tbl1.addElement(rnd.nextInt(25) + 3.14);                     tbl1.addElement((row % 3 == 0) ? false : true);                     tbl1.addElement((row % 5 == 0) ? false : true);                     if (row % 7 == 0) {                         tbl1.add(("Canc"));                     } else if (row % 6 == 0) {                         tbl1.add(("Del"));                     } else {                         tbl1.add(("New"));                     }                     tableModel.addRow(tbl1);                 }                 addTableListener();             }         };         SwingUtilities.invokeLater(doRun1);     }      private void addTableListener() {         tableModel.addTableModelListener(new TableModelListener() {              @Override             public void tableChanged(TableModelEvent tme) {                 if (tme.getType() == TableModelEvent.UPDATE) {                     System.out.println("");                     System.out.println("Cell " + tme.getFirstRow() + ", "                             + tme.getColumn() + " changed. The new value: "                             + tableModel.getValueAt(tme.getFirstRow(),                             tme.getColumn()));                 }             }         });     }      public void valueChanged(ListSelectionEvent le) {         int row = dialogTable.getSelectedRow();         int col = dialogTable.getSelectedColumn();         String str = "Selected Row(s): ";         int[] rows = dialogTable.getSelectedRows();         for (int i = 0; i < rows.length; i++) {             str += rows[i] + " ";         }         str += "Selected Column(s): ";         int[] cols = dialogTable.getSelectedColumns();         for (int i = 0; i < cols.length; i++) {             str += cols[i] + " ";         }         str += "Selected Cell: " + dialogTable.getSelectedRow() + ", " + dialogTable.getSelectedColumn();         System.out.println(str);         Object value = dialogTable.getValueAt(row, col);         System.out.println(String.valueOf(value));     }      private void createAndShowGUI() {         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);         frame.setLayout(new BorderLayout(10, 10));         addComponentsToPane(frame.getContentPane());         addData();         frame.setLocation(150, 150);         frame.setPreferredSize(new Dimension(400, 647));         frame.pack();         frame.setVisible(true);     }      public static void main(String[] args) {         Forum osFrame = new Forum();     }      public Forum() {         javax.swing.SwingUtilities.invokeLater(new Runnable() {              @Override             public void run() {                 createAndShowGUI();             }         });     }      private class myTableModel extends AbstractTableModel {          private static final long serialVersionUID = 1L;         private Vector<Vector<Object>> data;         private Vector<String> colNames;         private boolean[] _columnsVisible = {true, true, true, true, true};          myTableModel() {             this.colNames = new Vector<String>();             this.data = new Vector<Vector<Object>>();         }          myTableModel(Vector<String> colnames) {             this.colNames = colnames;             this.data = new Vector<Vector<Object>>();         }          public void resetTable() {             this.colNames.removeAllElements();             this.data.removeAllElements();         }          public void setColumnNames(Vector<String> colNames) {             this.colNames = colNames;             this.fireTableStructureChanged();         }          public void addRow(Vector<Object> data) {             this.data.add(data);             this.fireTableDataChanged();             this.fireTableStructureChanged();         }          public void removeRowAt(int row) {             this.data.removeElementAt(row);             this.fireTableDataChanged();         }          @Override         public int getColumnCount() {             return this.colNames.size();         }          @Override         public Class<?> getColumnClass(int colNum) {             switch (colNum) {                 case 0:                     return Integer.class;                 case 1:                     return Double.class;                 case 2:                     return Boolean.class;                 case 3:                     return Boolean.class;                 default:                     return String.class;             }         }          @Override         public boolean isCellEditable(int row, int colNum) {             switch (colNum) {                 case 2:                     return false;                 default:                     return true;             }         }          @Override         public String getColumnName(int colNum) {             return this.colNames.get(colNum);         }          @Override         public int getRowCount() {             return this.data.size();         }          @Override         public Object getValueAt(int row, int col) {             Vector<Object> value = this.data.get(row);             return value.get(col);         }          @Override         public void setValueAt(Object newVal, int row, int col) {             Vector<Object> aRow = data.elementAt(row);             aRow.remove(col);             aRow.insertElementAt(newVal, col);             fireTableCellUpdated(row, col);         }          public void setColumnVisible(int index, boolean visible) {             this._columnsVisible[index] = visible;             this.fireTableStructureChanged();         }     } }