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[英]KeyListeners for a JComboBox which is used as a cell editor in a table
[英]Dynamically filling a JComboBox when it's used as a table editor
我有一个用例(在Java Swing中),其中某些JTable
列必须可以通过JComboBox
编辑器进行编辑,但是可选值列表取决于行的域对象(我使用的是自定义TableModel
)。
CellEditor
界面具有停止或取消编辑时要调用的事件,但是没有启动编辑的事件(我希望这是填充选择值列表的好地方)。
开始对单元格进行编辑时如何填充组合框?
ComboBox中可用的项目是其模型的责任。 自定义您的ComboBoxModel (尤其是getElementAt(int)
方法),以便它查询有问题的域对象。
您可能要扩展DefaultComboBoxModel
而不是从头开始实现接口。
这是一个问题,我必须在今年早些时候解决(下面的代码来自该项目)。 解决方案是为组合框创建专用模型:
mEntityListModel = getMyEntityModel();
T[] items = (T[]) Array.newInstance(type, mEntityListModel.getSize());
for (int i = 0; i < items.length; i++) {
items[i] = mEntityListModel.getElementAt(i);
}
mComboBoxModel = new DefaultComboBoxModel<T>(items);
并使用组合框模型均衡实体列表中的每个更改:
mEntityListModel.addListDataListener(new DataListener());// make a better MVC solution if you like
private class DataListener implements ListDataListener {
@Override
public void intervalAdded(ListDataEvent e) {
mComboBoxModel.insertElementAt(mEntityListModel.getElementAt(e.getIndex0()), e.getIndex0());
}
@Override
public void intervalRemoved(ListDataEvent e) {
Object deletedElement = mComboBoxModel.getElementAt(e.getIndex0());
// Clear the combobox selection, if the item is deleted!
if (mSelectionManager.isSelected(deletedElement)) {
mSelectionManager.setSelectedItem(null);
}
mComboBoxModel.removeElementAt(e.getIndex0());
}
@Override
public void contentsChanged(ListDataEvent e) {
intervalRemoved(e);
intervalAdded(e);
}
}
旁注:这是表的组合框中的更改被注册的方式:
tablecolumn.getCellEditor()
.addCellEditorListener(new CellChangeListener());
private class CellChangeListener implements CellEditorListener {
@Override
public void editingStopped(ChangeEvent e) {
DefaultCellEditor editor;
Object newValue;
if (e.getSource() instanceof DefaultCellEditor) {
editor = (DefaultCellEditor) e.getSource();
newValue = editor.getCellEditorValue();
if (newValue != null) {
//set the newValue for the combobox selection manager
}
}
}
@Override
public void editingCanceled(ChangeEvent e) {
}
}
如您所见,组合框项目列表在编辑器开始工作之前已更新。 编辑者不对该工作负责。
一种方法是重写JTable的getCellEditor(...)
方法:
import java.awt.*;
import java.util.List;
import java.util.ArrayList;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.table.*;
public class TableComboBoxByRow extends JPanel
{
List<String[]> editorData = new ArrayList<String[]>(3);
public TableComboBoxByRow()
{
setLayout( new BorderLayout() );
// Create the editorData to be used for each row
editorData.add( new String[]{ "Red", "Blue", "Green" } );
editorData.add( new String[]{ "Circle", "Square", "Triangle" } );
editorData.add( new String[]{ "Apple", "Orange", "Banana" } );
// Create the table with default data
Object[][] data =
{
{"Color", "Red"},
{"Shape", "Square"},
{"Fruit", "Banana"},
{"Plain", "Text"}
};
String[] columnNames = {"Type","Value"};
DefaultTableModel model = new DefaultTableModel(data, columnNames);
JTable table = new JTable(model)
{
// Determine editor to be used by row
public TableCellEditor getCellEditor(int row, int column)
{
int modelColumn = convertColumnIndexToModel( column );
if (modelColumn == 1 && row < 3)
{
JComboBox<String> comboBox1 = new JComboBox<String>( editorData.get(row));
return new DefaultCellEditor( comboBox1 );
}
else
return super.getCellEditor(row, column);
}
};
JScrollPane scrollPane = new JScrollPane( table );
add( scrollPane );
}
private static void createAndShowUI()
{
JFrame frame = new JFrame("Table Combo Box by Row");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add( new TableComboBoxByRow() );
frame.setSize(200, 200);
frame.setLocationByPlatform( true );
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowUI();
}
});
}
}
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