Question

我希望我的JComboBox将多个选项组合在一起，类似于HTML optgroup：

<select>  
 <optgroup label="A">  
  <option/>
  <option/>  
 </optgroup>
</select>

我在Swing中找不到任何解决方案。操作Combobox的UI-Renderer似乎是一个坏主意，因为它是OS＆amp; L＆amp; F依赖（并且它们是私有的，因此无法扩展）。

Answer 1

将以下实现视为如何应用自定义样式和创建不可选项的基本指南：

public class ExtendedComboBox extends JComboBox {

    public ExtendedComboBox() {
        setModel(new ExtendedComboBoxModel());
        setRenderer(new ExtendedListCellRenderer());
    }

    public void addDelimiter(String text) {
        this.addItem(new Delimiter(text));
    }

    private static class ExtendedComboBoxModel extends DefaultComboBoxModel {
        @Override
        public void setSelectedItem(Object anObject) {
            if (!(anObject instanceof Delimiter)) {
                super.setSelectedItem(anObject);
            } else {
                int index = getIndexOf(anObject);
                if (index < getSize()) {
                    setSelectedItem(getElementAt(index+1));
                }
            }
        }

    }

    private static class ExtendedListCellRenderer 
                    extends DefaultListCellRenderer {

        @Override
        public Component getListCellRendererComponent(JList list, Object value,
                        int index, boolean isSelected, boolean cellHasFocus) {
            if (!(value instanceof Delimiter)) {
                return super.getListCellRendererComponent(list, value, index,
                        isSelected, cellHasFocus);
            } else {
                JLabel label = new JLabel(value.toString());
                Font f = label.getFont();
                label.setFont(f.deriveFont(f.getStyle() 
                           | Font.BOLD | Font.ITALIC));
                return label;
            }
        }
    }

    private static class Delimiter {
        private String text;

        private Delimiter(String text) {
            this.text = text;
        }

        @Override
        public String toString() {
            return text.toString();
        }
    }
}

Answer 2

您可以在自定义渲染器中执行此操作，如How to Use Combo Boxes: Providing a Custom Renderer中所述。

Answer 3

我不相信有一种简单的方法可以做到这一点，但有一种方法可以做到。

我会实现一个数据模型类，它指示您在上面描述的分组。将这些数据模型的实例放在javax.swing.ComboBoxModel实现实例中。

然后，您可以使用文本数据的缩进来实现javax.swing.ListCellRenderer格式化输出。您可能只想扩展javax.swing.DefaultListCellRenderer或者可能从Java源代码中借用它的实现批发。

对于L＆amp; F，您应该能够使用上述方法保持在正常的指导范围内，并且您不必为解决如何实施它而斗争。看看默认的Swing组件，他们将提供有关如何处理L＆amp; F的大量见解。

此外，我认为有一些机制（您必须原谅我，自从我完成完整的Swing开发以来已经过了几年），以便您确定某个项目是否可选。

Answer 4

我今天自己也想要这个，而且我花了一天时间把它拼凑起来用JList而不是建议的JComboBox来实现类似的模型。我终于想出了一个使用GlazedLists EventList和SeparatorList以及相应的DefaultEventListModel的解决方案。我重写了CellRenderer和DefaultListSelectionModel。最后，我在自己的问题上发表了自己的答案：How to prevent selection of SeparatorList.Separator in a JList?

这是我的最终工作代码：

public class MyFrame extends javax.swing.JFrame {
    private final EventList<BibleVersion> bibleVersions;
    private final SeparatorList<BibleVersion> versionsByLang;
    private boolean[] enabledFlags;

    public MyFrame(){
        bibleVersions = new BasicEventList<>();
        bibleVersions.add(new BibleVersion("CEI2008", "Testo della Conferenza Episcopale Italiana", "2008", "Italian"));
        bibleVersions.add(new BibleVersion("LUZZI", "Diodati Nuova Riveduta - Luzzi", "1927", "Italian"));
        bibleVersions.add(new BibleVersion("NVBSE", "Nova Vulgata - Bibliorum Sacrorum Editio", "1979", "Latin"));
        bibleVersions.add(new BibleVersion("NABRE", "New American Bible - Revised Edition", "2011", "English"));
        bibleVersions.add(new BibleVersion("KJV", "King James Version", "1611", "English"));
        versionsByLang = new SeparatorList<>(bibleVersions, new VersionComparator(),1, 1000);
        int listLength = versionsByLang.size();
        enabledFlags = new boolean[listLength];

        ListIterator itr = versionsByLang.listIterator();
        while(itr.hasNext()){
            enabledFlags[itr.nextIndex()] = !(itr.next().getClass().getSimpleName().equals("GroupSeparator"));
        }
        jList = new javax.swing.JList();
        jList.setModel(new DefaultEventListModel<>(versionsByLang));
        jList.setCellRenderer(new VersionCellRenderer());
        jList.setSelectionModel(new DisabledItemSelectionModel());
        ListSelectionModel listSelectionModel = jList.getSelectionModel();
        listSelectionModel.addListSelectionListener(new SharedListSelectionHandler());

    }

    public static class BibleVersion {
        private String abbrev;
        private String fullname;
        private String year;
        private String lang;

        public BibleVersion(String abbrev, String fullname, String year, String lang) {
            this.abbrev = abbrev;
            this.fullname = fullname;
            this.year = year;
            this.lang = lang;
        }        

        public String getAbbrev() {
            return abbrev;
        }

        public void setAbbrev(String abbrev) {
            this.abbrev = abbrev;
        }

        public String getFullname() {
            return fullname;
        }

        public void setFullname(String fullname) {
            this.fullname = fullname;
        }

        public String getYear() {
            return year;
        }

        public void setYear(String year) {
            this.year = year;
        }

        public String getLang() {
            return lang;
        }

        public void setLang(String lang) {
            this.lang = lang;
        }

        @Override
        public String toString() {
            return this.getAbbrev() + " — " + this.getFullname() + " (" + this.getYear() + ")"; //To change body of generated methods, choose Tools | Templates.
        }                

    }

    private static class VersionComparator implements Comparator<BibleVersion> {

        @Override
        public int compare(BibleVersion o1, BibleVersion o2) {
            return o1.getLang().compareTo(o2.getLang());
        }            

    }

    private static class VersionCellRenderer extends DefaultListCellRenderer{

        @Override
        public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
            JLabel label = (JLabel) super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);

            if (value instanceof SeparatorList.Separator) {
                SeparatorList.Separator separator = (SeparatorList.Separator) value;
                BibleVersion bibleversion = (BibleVersion)separator.getGroup().get(0);
                String lbl = "-- " + bibleversion.getLang() + " --";
                label.setText(lbl);
                label.setFont(label.getFont().deriveFont(Font.BOLD));
                label.setBackground(Color.decode("#004400"));
                label.setBorder(BorderFactory.createEmptyBorder(0,5,0,0));
                label.setEnabled(false);
            } else {
                label.setFont(label.getFont().deriveFont(Font.PLAIN));
                label.setBorder(BorderFactory.createEmptyBorder(0,15,0,0));
            }

            return label;
        }
    }

private class DisabledItemSelectionModel extends DefaultListSelectionModel {

    private static final long serialVersionUID = 1L;

    @Override
    public void setSelectionInterval(int index0, int index1) {
        if(index0 < index1){
            for (int i = index0; i <= index1; i++){
                if(enabledFlags[i]){
                    super.addSelectionInterval(i, i);
                }
            }
        }
        else if(index1 < index0){
            for (int i = index1; i <= index0; i++){
                if(enabledFlags[i]){
                    super.addSelectionInterval(i, i);
                }
            }
        }
        else if(index0 == index1){
            if(enabledFlags[index0]){ super.setSelectionInterval(index0,index0); }
        }
    }

    @Override
    public void addSelectionInterval(int index0, int index1) {
        if(index0 < index1){
            for (int i = index0; i <= index1; i++){
                if(enabledFlags[i]){
                    super.addSelectionInterval(i, i);
                }
            }
        }
        else if(index1 < index0){
            for (int i = index1; i <= index0; i++){
                if(enabledFlags[i]){
                    super.addSelectionInterval(i, i);
                }
            }
        }
        else if(index0 == index1){
            if(enabledFlags[index0]){ super.addSelectionInterval(index0,index0); }
        }
    }        

}

private class SharedListSelectionHandler implements ListSelectionListener {
    @Override
    public void valueChanged(ListSelectionEvent e) {
        ListSelectionModel lsm = (ListSelectionModel)e.getSource();
        StringBuilder output = new StringBuilder();
        int firstIndex = e.getFirstIndex();
        int lastIndex = e.getLastIndex();
        boolean isAdjusting = e.getValueIsAdjusting();
        output.append("Event for indexes ");
        output.append(firstIndex);
        output.append(" - ");
        output.append(lastIndex);
        output.append("; isAdjusting is ");
        output.append(isAdjusting);
        output.append("; selected indexes:");

        if (lsm.isSelectionEmpty()) {
            output.append(" <none>");
        } else {
            // Find out which indexes are selected.
            int minIndex = lsm.getMinSelectionIndex();
            int maxIndex = lsm.getMaxSelectionIndex();
            for (int i = minIndex; i <= maxIndex; i++) {
                if (lsm.isSelectedIndex(i)) {
                    output.append(" ");
                    output.append(i);
                }
            }
        }
        output.append(System.getProperty("line.separator"));
        System.out.println(output.toString());
    }
}


}

什么是Swing - 相当于HTML <optgroup> </optgroup>

4 个答案: