问题
Probably a noob question, but im new to java. I have a need for a checkbox list which I found is not supported in swing, but I found this custom control here
http://www.devx.com/tips/Tip/5342
So I created a class file named CheckBoxList, and copied the code from the link into it:
import javax.swing.*;
import javax.swing.border.*;
import java.awt.*;
import java.awt.event.*;
public class CheckBoxList extends JList
{
protected static Border noFocusBorder =
new EmptyBorder(1, 1, 1, 1);
public CheckBoxList()
{
setCellRenderer(new CellRenderer());
addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
int index = locationToIndex(e.getPoint());
if (index != -1) {
JCheckBox checkbox = (JCheckBox)
getModel().getElementAt(index);
checkbox.setSelected(
!checkbox.isSelected());
repaint();
}
}
}
);
setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
}
protected class CellRenderer implements ListCellRenderer
{
public Component getListCellRendererComponent(
JList list, Object value, int index,
boolean isSelected, boolean cellHasFocus)
{
JCheckBox checkbox = (JCheckBox) value;
checkbox.setBackground(isSelected ?
getSelectionBackground() : getBackground());
checkbox.setForeground(isSelected ?
getSelectionForeground() : getForeground());
checkbox.setEnabled(isEnabled());
checkbox.setFont(getFont());
checkbox.setFocusPainted(false);
checkbox.setBorderPainted(true);
checkbox.setBorder(isSelected ?
UIManager.getBorder(
"List.focusCellHighlightBorder") : noFocusBorder);
return checkbox;
}
}
}
The problem is I don't know how to implement it in my GUI file. I tried a lot of code, but they never showed an example. Just
To use the class, simply instantiate it, then pass it an array of JCheckBox objects (or subclasses of JCheckBox objects) by calling setListData
So does that mean that I will not see the control in the Graphical Design view? My client wants to be able to edit it himself and add stuff so I want it to be easy and graphical if possible. If someone could show an example of instantiating it or give a good hint I would appreciate it. Thanks!
回答1:
Can you just tell me how?
Use a one column JTable and an appropriate renderer and editor. Based on this example, the code below relies on the default renderer for a data value of type Boolean.Class. A more general example is cited here.
import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;
import javax.swing.BorderFactory;
import javax.swing.DefaultListModel;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.event.TableModelEvent;
import javax.swing.event.TableModelListener;
import javax.swing.table.AbstractTableModel;
import javax.swing.table.TableCellRenderer;
/** @see https://stackoverflow.com/a/13919878/230513 */
public class CheckTable {
private static final CheckModel model = new CheckModel(5000);
private static final JTable table = new JTable(model) {
@Override
public Dimension getPreferredScrollableViewportSize() {
return new Dimension(150, 300);
}
@Override
public Component prepareRenderer(TableCellRenderer renderer, int row, int column) {
JCheckBox jcb = (JCheckBox) super.prepareRenderer(renderer, row, column);
jcb.setHorizontalTextPosition(JCheckBox.LEADING);
jcb.setText(String.valueOf(row));
return jcb;
}
};
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
JFrame f = new JFrame("CheckTable");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setLayout(new GridLayout(1, 0));
f.add(new JScrollPane(table));
f.add(new DisplayPanel(model));
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
});
}
private static class DisplayPanel extends JPanel {
private DefaultListModel dlm = new DefaultListModel();
private JList list = new JList(dlm);
public DisplayPanel(final CheckModel model) {
super(new GridLayout());
this.setBorder(BorderFactory.createTitledBorder("Checked"));
this.add(new JScrollPane(list));
model.addTableModelListener(new TableModelListener() {
@Override
public void tableChanged(TableModelEvent e) {
dlm.removeAllElements();
for (Integer integer : model.checked) {
dlm.addElement(integer);
}
}
});
}
}
private static class CheckModel extends AbstractTableModel {
private final int rows;
private List<Boolean> rowList;
private Set<Integer> checked = new TreeSet<Integer>();
public CheckModel(int rows) {
this.rows = rows;
rowList = new ArrayList<Boolean>(rows);
for (int i = 0; i < rows; i++) {
rowList.add(Boolean.FALSE);
}
}
@Override
public int getRowCount() {
return rows;
}
@Override
public int getColumnCount() {
return 1;
}
@Override
public String getColumnName(int col) {
return "Column " + col;
}
@Override
public Object getValueAt(int row, int col) {
return rowList.get(row);
}
@Override
public void setValueAt(Object aValue, int row, int col) {
boolean b = (Boolean) aValue;
rowList.set(row, b);
if (b) {
checked.add(row);
} else {
checked.remove(row);
}
fireTableRowsUpdated(row, row);
}
@Override
public Class<?> getColumnClass(int col) {
return getValueAt(0, col).getClass();
}
@Override
public boolean isCellEditable(int row, int col) {
return true;
}
}
}
回答2:
The code is expecting a list of JCheckBox objects - so this works
CheckBoxList cbList = new CheckBoxList(); // the class you have
JCheckBox check1 = new JCheckBox("One");
JCheckBox check2 = new JCheckBox("two");
JCheckBox[] myList = { check1, check2}; list of checkbox object
cbList.setListData(myList); // set the list data for the object
Small Swing program using your class below
util;
import javax.swing.*;
public class HelloWorldSwing {
private static void createAndShowGUI() {
//Create and set up the window.
JFrame frame = new JFrame("HelloWorldSwing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
CheckBoxList cbList = new CheckBoxList();
JCheckBox check1 = new JCheckBox("One");
JCheckBox check2 = new JCheckBox("two");
JCheckBox[] myList = { check1, check2};
cbList.setListData(myList);
frame.getContentPane().add(cbList);
//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();
}
});
}
}
来源：https://stackoverflow.com/questions/21358240/how-to-implement-checkbox-list-java