在JTable的初级教程中往往会提到，使用TableModel的 addTableModelListener方法可以监听单元格数据的变更，在其事件处理函，数tableChanged中，可以通过e.getColumn()，e.getFirstRow()，e.getLastRow()，e.getType()来获取变更发生的位置和变更的类型（插入、更新或删除）。然而该方法存在2个致命的问题：
1.双击单元格使其处于可编辑状态后，即使没有做出任何修改，当单元格失去焦点时，该事件将被激活。
2.通过该事件你可以获取单元格最新的数据，却无法获取原有数据。
经过一番搜索发现该文章已经解决了这个问题Table Cell Listener，作者自己实现了一个单元格监听器TableCellListener，它订阅了指定table的addPropertyChangeListener，根据e.getPropertyName()来识别单元格编辑事件，根据table.isEditing()方法来判断单元格正在编辑还是编辑完毕。如果是正在编辑，则记录单元格位置和原因数据；如果已经编辑完毕，则记录新数据并与原有数据进行比对，如果不一致则说明单元格数据发生了变更，则激活指定响应函数。
测试用例如下：
TableDemo.java
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* modification, are permitted provided that the following conditions
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*
* - Neither the name of Oracle or the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/ package TableCellListenerTest; /*
* TableDemo.java requires no other files.
*/ import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.AbstractTableModel; import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent; /**
* TableDemo is just like SimpleTableDemo, except that it
* uses a custom TableModel.
*/
public class TableDemo extends JPanel {
private boolean DEBUG = false; public TableDemo() {
super(new GridLayout(1,0)); JTable table = new JTable(new MyTableModel());
table.setPreferredScrollableViewportSize(new Dimension(500, 70));
table.setFillsViewportHeight(true); //Create the scroll pane and add the table to it.
JScrollPane scrollPane = new JScrollPane(table); //Add the scroll pane to this panel.
add(scrollPane);
Action action = new AbstractAction()
{
public void actionPerformed(ActionEvent e)
{
TableCellListener tcl = (TableCellListener)e.getSource();
System.out.printf("cell changed%n");
System.out.println("Row : " + tcl.getRow());
System.out.println("Column: " + tcl.getColumn());
System.out.println("Old : " + tcl.getOldValue());
System.out.println("New : " + tcl.getNewValue());
}
};
TableCellListener tcl = new TableCellListener(table, action);
} class MyTableModel extends AbstractTableModel {
private String[] columnNames = {"First Name",
"Last Name",
"Sport",
"# of Years",
"Vegetarian"};
private Object[][] data = {
{"Kathy", "Smith",
"Snowboarding", new Integer(5), new Boolean(false)},
{"John", "Doe",
"Rowing", new Integer(3), new Boolean(true)},
{"Sue", "Black",
"Knitting", new Integer(2), new Boolean(false)},
{"Jane", "White",
"Speed reading", new Integer(20), new Boolean(true)},
{"Joe", "Brown",
"Pool", new Integer(10), new Boolean(false)}
}; public int getColumnCount() {
return columnNames.length;
} public int getRowCount() {
return data.length;
} public String getColumnName(int col) {
return columnNames[col];
} public Object getValueAt(int row, int col) {
return data[row][col];
} /*
* JTable uses this method to determine the default renderer/
* editor for each cell. If we didn't implement this method,
* then the last column would contain text ("true"/"false"),
* rather than a check box.
*/
public Class getColumnClass(int c) {
return getValueAt(0, c).getClass();
} /*
* Don't need to implement this method unless your table's
* editable.
*/
public boolean isCellEditable(int row, int col) {
//Note that the data/cell address is constant,
//no matter where the cell appears onscreen.
if (col < 2) {
return false;
} else {
return true;
}
} /*
* Don't need to implement this method unless your table's
* data can change.
*/
public void setValueAt(Object value, int row, int col) {
if (DEBUG) {
System.out.println("Setting value at " + row + "," + col
+ " to " + value
+ " (an instance of "
+ value.getClass() + ")");
} data[row][col] = value;
fireTableCellUpdated(row, col); if (DEBUG) {
System.out.println("New value of data:");
printDebugData();
}
} private void printDebugData() {
int numRows = getRowCount();
int numCols = getColumnCount(); for (int i=0; i < numRows; i++) {
System.out.print(" row " + i + ":");
for (int j=0; j < numCols; j++) {
System.out.print(" " + data[i][j]);
}
System.out.println();
}
System.out.println("--------------------------");
}
} /**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event-dispatching thread.
*/
private static void createAndShowGUI() {
//Create and set up the window.
JFrame frame = new JFrame("TableDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Create and set up the content pane.
TableDemo newContentPane = new TableDemo();
newContentPane.setOpaque(true); //content panes must be opaque
frame.setContentPane(newContentPane); //Display the window.
frame.pack();
frame.setVisible(true);
} public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
TableCellListener.java
package DefaultTableModelDemo;
import java.awt.event.*;
import javax.swing.*;
import java.beans.*; /*
* This class listens for changes made to the data in the table via the
* TableCellEditor. When editing is started, the value of the cell is saved
* When editing is stopped the new value is saved. When the oold and new
* values are different, then the provided Action is invoked.
*
* The source of the Action is a TableCellListener instance.
*/
public class TableCellListener implements PropertyChangeListener, Runnable
{
private JTable table;
private Action action; private int row;
private int column;
private Object oldValue;
private Object newValue; /**
* Create a TableCellListener.
*
* @param table the table to be monitored for data changes
* @param action the Action to invoke when cell data is changed
*/ public TableCellListener(JTable table, Action action)
{
this.table = table;
this.action = action;
this.table.addPropertyChangeListener( this );
} /**
* Create a TableCellListener with a copy of all the data relevant to
* the change of data for a given cell.
*
* @param row the row of the changed cell
* @param column the column of the changed cell
* @param oldValue the old data of the changed cell
* @param newValue the new data of the changed cell
*/
private TableCellListener(JTable table, int row, int column, Object oldValue, Object newValue)
{
this.table = table;
this.row = row;
this.column = column;
this.oldValue = oldValue;
this.newValue = newValue;
} /**
* Get the column that was last edited
*
* @return the column that was edited
*/
public int getColumn()
{
return column;
} /**
* Get the new value in the cell
*
* @return the new value in the cell
*/
public Object getNewValue()
{
return newValue;
} /**
* Get the old value of the cell
*
* @return the old value of the cell
*/
public Object getOldValue()
{
return oldValue;
} /**
* Get the row that was last edited
*
* @return the row that was edited
*/
public int getRow()
{
return row;
} /**
* Get the table of the cell that was changed
*
* @return the table of the cell that was changed
*/
public JTable getTable()
{
return table;
}
//
// Implement the PropertyChangeListener interface
//
@Override
public void propertyChange(PropertyChangeEvent e)
{
// A cell has started/stopped editing if ("tableCellEditor".equals(e.getPropertyName()))
{
if (table.isEditing()){
//System.out.printf("tableCellEditor is editing..%n");
processEditingStarted();
}
else{
//System.out.printf("tableCellEditor editing stopped..%n");
processEditingStopped();
} }
} /*
* Save information of the cell about to be edited
*/
private void processEditingStarted()
{
// The invokeLater is necessary because the editing row and editing
// column of the table have not been set when the "tableCellEditor"
// PropertyChangeEvent is fired.
// This results in the "run" method being invoked SwingUtilities.invokeLater( this );
}
/*
* See above.
*/
@Override
public void run()
{
row = table.convertRowIndexToModel( table.getEditingRow() );
column = table.convertColumnIndexToModel( table.getEditingColumn() );
oldValue = table.getModel().getValueAt(row, column);
//这里应对oldValue为null的情况做处理，否则将导致原值与新值均为空时仍被视为值改变
if(oldValue == null)
oldValue = "";
newValue = null;
} /*
* Update the Cell history when necessary
*/
private void processEditingStopped()
{
newValue = table.getModel().getValueAt(row, column);
//这里应对newValue为null的情况做处理，否则后面会抛出异常
if(newValue == null)
newValue = "";
// The data has changed, invoke the supplied Action
if (! newValue.equals(oldValue))
{
// Make a copy of the data in case another cell starts editing
// while processing this change TableCellListener tcl = new TableCellListener(
getTable(), getRow(), getColumn(), getOldValue(), getNewValue()); ActionEvent event = new ActionEvent(
tcl,
ActionEvent.ACTION_PERFORMED,
"");
action.actionPerformed(event);
}
}
}