Creating a Text Field That Mirrors the Value in the Anchor Cell in a JTable Component
In some spreadsheet applications, the value of the current cell
(anchor) is mirrored in a separate and conveniently larger text field.
Any changes to the current cell are immediately reflected in the text
field and vice versa. This example demonstrates how to set up a mirror
text field for the anchor cell in a table component.
In order to detect changes to the anchor cell, a
selection-changed listener
and a cell-value-changed listener must be added to the table.
See Getting the Anchor Cell in a JTable Component for more information about
the anchor cell.
JTable table = new JTable();
// Add data
// Create text field and add action
JTextField textField = new JTextField();
textField.setAction(new UpdateAnchorAction(table));
// Add selection listener to table
SelectionListener listener = new SelectionListener(table, textField);
table.getSelectionModel().addListSelectionListener(listener);
table.getColumnModel().getSelectionModel()
.addListSelectionListener(listener);
// Add value changed listener to table
table.getModel().addTableModelListener(new MyTableModelListener(table, textField));
// Create a frame and add both components to the frame
JFrame frame = new JFrame();
frame.getContentPane().add(new JScrollPane(table), BorderLayout.CENTER);
frame.getContentPane().add(textField, BorderLayout.NORTH);
frame.pack();
frame.setVisible(true);
public class SelectionListener implements ListSelectionListener {
JTable table;
JTextField textField;
// It is necessary to keep the table since it is not possible
// to determine the table from the event's source
SelectionListener(JTable table, JTextField textField) {
this.table = table;
this.textField = textField;
}
// Update the text field whenever the anchor cell changes
public void valueChanged(ListSelectionEvent e) {
int rowIndex = table.getSelectionModel().getAnchorSelectionIndex();
int vColIndex = table.getColumnModel().getSelectionModel()
.getAnchorSelectionIndex();
// Get the value and set the text field
textField.setText((String)table.getValueAt(rowIndex, vColIndex));
}
}
public class MyTableModelListener implements TableModelListener {
JTable table;
JTextField textField;
// It is necessary to keep the table since it is not possible
// to determine the table from the event's source
MyTableModelListener(JTable table, JTextField textField) {
this.table = table;
this.textField = textField;
}
// Update the text field whenever the value in the anchor cell changes
public void tableChanged(TableModelEvent e) {
// Get anchor cell location
int rAnchor = table.getSelectionModel().getAnchorSelectionIndex();
int vcAnchor = table.getColumnModel().getSelectionModel()
.getAnchorSelectionIndex();
// This method is defined in
// Converting a Column Index Between the View and Model in a JTable Component
int mcAnchor = toModel(table, vcAnchor);
// Get affected rows and columns
int firstRow = e.getFirstRow();
int lastRow = e.getLastRow();
int mColIndex = e.getColumn();
if (firstRow != TableModelEvent.HEADER_ROW
&& rAnchor >= firstRow
&& rAnchor <= lastRow
&& (mColIndex == TableModelEvent.ALL_COLUMNS
|| mColIndex == mcAnchor)) {
// Set the text field with the new value
textField.setText((String)table.getValueAt(rAnchor, vcAnchor));
}
}
}
public class UpdateAnchorAction extends AbstractAction {
JTable table;
UpdateAnchorAction(JTable table) {
super("Set Anchor");
this.table = table;
}
// Update the value in the anchor cell whenever the text field changes
public void actionPerformed(ActionEvent evt) {
JTextField textField = (JTextField)evt.getSource();
// Get anchor cell location
int rAnchor = table.getSelectionModel().getAnchorSelectionIndex();
int vcAnchor = table.getColumnModel().getSelectionModel()
.getAnchorSelectionIndex();
table.setValueAt(textField.getText(), rAnchor, vcAnchor);
}
}
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