复选列表框，,public class

复选列表框，,public class

public class CheckBoxJList extends JList     implements ListSelectionListener {    static Color listForeground, listBackground;    static {       UIDefaults uid = UIManager.getLookAndFeel().getDefaults();       listForeground =uid.getColor ("List.foreground");       listBackground =uid.getColor ("List.background");    }    HashSet selectionCache = new HashSet();    int toggleIndex = -1;    boolean toggleWasSelected;    public CheckBoxJList() {       super();       setCellRenderer (new CheckBoxListCellRenderer());       addListSelectionListener (this);    }public void valueChanged (ListSelectionEvent lse) {        if (! lse.getValueIsAdjusting()) {         removeListSelectionListener (this);        // determine if this selection has added or removed items        HashSet newSelections = new HashSet();        int size = getModel().getSize();        for (int i=0; i<size; i++) {             if (getSelectionModel().isSelectedIndex(i)) {                 newSelections.add (new Integer(i));             }        }        // turn on everything that was selected previously        Iterator it = selectionCache.iterator();        while (it.hasNext()) {            int index = ((Integer) it.next()).intValue();                            getSelectionModel().addSelectionInterval(index, index);         }        // add or remove the delta        it = newSelections.iterator();        while (it.hasNext()) {            Integer nextInt = (Integer) it.next();            int index = nextInt.intValue();            if (selectionCache.contains (nextInt))                getSelectionModel().removeSelectionInterval (index, index);   else                               getSelectionModel().addSelectionInterval (index, index);         }        // save selections for next time        selectionCache.clear();        for (int i=0; i<size; i++) {             if (getSelectionModel().isSelectedIndex(i)) {                 selectionCache.add (new Integer(i));             }        }        addListSelectionListener (this);     } }class CheckBoxListCellRenderer extends JComponent     implements ListCellRenderer {     DefaultListCellRenderer defaultComp;     JCheckBox checkbox;        public CheckBoxListCellRenderer() {        setLayout (new BorderLayout());        defaultComp = new DefaultListCellRenderer();        checkbox = new JCheckBox();        add (checkbox, BorderLayout.WEST);        add (defaultComp, BorderLayout.CENTER);    }    public Component getListCellRendererComponent(JList list,                                                  Object value,                                                  int index,                                                  boolean isSelected,                                                  boolean cellHasFocus){defaultComp.getListCellRendererComponent (list, value, index,                                              isSelected, cellHasFocus);     checkbox.setSelected (isSelected);            Component[] comps = getComponents();     for (int i=0; i<comps.length; i++) {         comps[i].setForeground (listForeground);         comps[i].setBackground (listBackground);    }    return this;  } }   public static void main (String[] args) {        JList list = new CheckBoxJList ();        DefaultListModel defModel = new DefaultListModel();        list.setModel (defModel);        String[] listItems = {           "Chris", "Joshua", "Daniel", "Michael",           "Don", "Kimi", "Kelly", "Keagan"        };        Iterator it = Arrays.asList(listItems).iterator();        while (it.hasNext())            defModel.addElement (it.next());        // show list        JScrollPane scroller =            new JScrollPane (list,                              ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,                              ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);        JFrame frame = new JFrame ("Checkbox JList");        frame.getContentPane().add (scroller);        frame.pack();        frame.setVisible(true);     }}//该片段来自于http://byrx.net