更改 JComboBox 的字体颜色

Question

Using netbeans, I have this code in my comboBox which generates name suggestions.

  private void createAndShowGui() {
  if(comboBox.isDisplayable()){
    txtNameID.getDocument().addDocumentListener(new DocumentListener() {
        @Override
        public void insertUpdate(DocumentEvent e) {

            Runnable doAssist = new Runnable() {
                @Override
                public void run() {
                    comboFilter(txtNameID.getText());
                    System.out.println(txtNameID.getText());
                }
            };
            SwingUtilities.invokeLater(doAssist);
        }

        @Override
        public void removeUpdate(DocumentEvent e) {
            Runnable doAssist = new Runnable() {
                @Override
                public void run() {
                    comboFilter(txtNameID.getText());
                }
            };
            SwingUtilities.invokeLater(doAssist);
        }

        @Override
        public void changedUpdate(DocumentEvent e) {
            // plain text components dont fire this
        }
    });

    comboBox.addActionListener((ActionEvent e) -> {
        txtNameID.setText(comboBox.getSelectedItem().toString());
       
    });
 }
}

//COMBOBOX SUGGEST
public void comboFilter(String enteredText) {
    java.util.List<String> filterArray = new ArrayList<String>();

    String lname = "";
    String fname = "";
    String mi = "";
    String id = "";

    try {
        con = databasePatient.ConnectDb();
        String str = "SELECT * FROM patient_record WHERE firstname  LIKE '" + enteredText + "%' OR lastname  LIKE '" + enteredText + "%' OR patient_id  LIKE '" + enteredText + "%' OR name  LIKE '" + enteredText + "%' OR name  LIKE '%" + enteredText + "%'";
        Statement stmt = con.createStatement();
        ResultSet rs2 = stmt.executeQuery(str);

        if (enteredText.equals("")) {
            String str1 = "";
            filterArray.add(str1);
        } else 
            if (rs2.next()) {
            Statement stmt1 = con.createStatement();
            String str2 = "SELECT * FROM patient_record WHERE firstname  LIKE '" + enteredText + "%' OR lastname  LIKE '" + enteredText + "%' OR patient_id  LIKE '" + enteredText + "%'OR name  LIKE '" + enteredText + "%' OR name  LIKE '%" + enteredText + "%'";
            ResultSet rs = stmt1.executeQuery(str2);

            while (rs.next()) {
                String names = rs.getString("name");
                String str1 = names;
                filterArray.add(str1);
            }
            
        } else {
            String str1 = "";
            filterArray.add(str1);

        }
    } catch (Exception ex) {
        ex.printStackTrace();
    }
    listOfNames.forEach((item) -> {
        if (item.contains(enteredText)) {
            filterArray.add(item);
        }
    });

    if (filterArray.size() > 0) {
        comboBox.setModel(new DefaultComboBoxModel(filterArray.toArray()));
    }
}

My problem is that I can't change the foreground of the text in the comboBox by simply putting setForeground. The default color of the text is black and I need to make it white. Can anyone help me out here? Help would be much appreciated. Thank you!

Answer 1

I did not try your code.

Your problem may stem from the fact that a ComboBox is a combination of items: A field that shows a selected value, a button to open a list and the list itself. Now if you set the combobox foreground color I guess this would have effect on the field itself but probably not on the button and definitely not on the list.

Am I right until here? In that case you should look how to modify rendering of the current entry, the editing of the current entry and the rendering of the list.

• https://docs.oracle.com/en/java/javase/11/docs/api/java.desktop/javax/swing/JComboBox.html#setEditor(javax.swing.ComboBoxEditor)
• https://docs.oracle.com/en/java/javase/11/docs/api/java.desktop/javax/swing/JComboBox.html#setRenderer(javax.swing.ListCellRenderer)

If you end up restyling a lot of single components (I guess you want to go towards black background and white foreground), maybe you want to look at Pluggable Look and Feel (PLAF) .