Java – how to configure jcombobox not to select the first element when it is created?
•
Java
Question: @ h_ 403_ 2 @ update:
DefaultCombo@R_754_2419@Model model = new DefaultCombo@R_754_2419@Model();
model.setSelectedItem(null);
suggestionCombo@R_754_2419@ = new JCombo@R_754_2419@(model);
suggestionCombo@R_754_2419@.setModel(model);
suggestionCombo@R_754_2419@.removeAllItems();
for (int i = 0; i < suggestions.length; i++) {
suggestionCombo@R_754_2419@.addItem(suggestions[i]);
}
suggestionCombo@R_754_2419@.setSelectedIndex(-1);
suggestionCombo@R_754_2419@.setEnabled(true);
suggestionCombo@R_754_2419@ = new JCombo@R_754_2419@();
suggestionCombo@R_754_2419@.setEditable(false);
suggestionCombo@R_754_2419@.setPreferredSize(new Dimension(25,25));
suggestionCombo@R_754_2419@.addActionListener(new SuggestionCombo@R_754_2419@Listener());
package components;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.Insets;
import java.awt.Rectangle;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import javax.swing.JButton;
import javax.swing.JCombo@R_754_2419@;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTextArea;
import javax.swing.JTextPane;
import javax.swing.JToolBar;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.event.CaretEvent;
import javax.swing.event.CaretListener;
import javax.swing.text.AbstractDocument;
import javax.swing.text.BadLocationException;
import javax.swing.text.StyledDocument;
public class Temp extends JFrame {
JTextPane textPane;
AbstractDocument doc;
JTextArea changeLog;
String newline = "\n";
private JCombo@R_754_2419@ suggestionCombo@R_754_2419@;
private JPanel suggestionPanel;
private JLabel suggestionLabel;
private JButton openButton,saveButton,aboutButton;
public Temp() {
super("Snort Ruleset IDE");
//Create the text pane and configure it.
textPane = new JTextPane();
textPane.setCaretPosition(0);
textPane.setMargin(new Insets(5,5,5));
StyledDocument styledDoc = textPane.getStyledDocument();
if (styledDoc instanceof AbstractDocument) {
doc = (AbstractDocument) styledDoc;
//doc.setDocumentFilter(new DocumentSizeFilter(MAX_CHARACTERS));
} else {
System.err.println("Text pane's document isn't an AbstractDocument!");
System.exit(-1);
}
JScrollPane scrollPane = new JScrollPane(textPane);
scrollPane.setPreferredSize(new Dimension(700,350));
//Create the text area for the status log and configure it.
//changeLog = new JTextArea(10,30);
//changeLog.setEditable(false);
//JScrollPane scrollPaneForLog = new JScrollPane(changeLog);
//Create a JPanel for the suggestion area
suggestionPanel = new JPanel(new BorderLayout());
suggestionPanel.setVisible(true);
suggestionLabel = new JLabel("Suggestion is not active at the moment.");
suggestionLabel.setPreferredSize(new Dimension(100,50));
suggestionLabel.setMaximumSize(new Dimension(100,50));
suggestionCombo@R_754_2419@ = new JCombo@R_754_2419@();
suggestionCombo@R_754_2419@.setEditable(false);
suggestionCombo@R_754_2419@.setPreferredSize(new Dimension(25,25));
//suggestionCombo@R_754_2419@.addActionListener(new SuggestionCombo@R_754_2419@Listener());
suggestionCombo@R_754_2419@.addItemListener(new SuggestionCombo@R_754_2419@Listener());
//suggestionCombo@R_754_2419@.setSelectedIndex(-1);
//add the suggestionLabel and suggestionCombo@R_754_2419@ to pane
suggestionPanel.add(suggestionLabel,BorderLayout.CENTER);
suggestionPanel.add(suggestionCombo@R_754_2419@,BorderLayout.PAGE_END);
JScrollPane sp = new JScrollPane(suggestionPanel);
JScrollPane scrollPaneForSuggestion = new JScrollPane(suggestionPanel);
//Create a split pane for the change log and the text area.
JSplitPane splitPane = new JSplitPane(
JSplitPane.VERTICAL_SPLIT,scrollPane,scrollPaneForSuggestion);
splitPane.setOneTouchExpandable(true);
splitPane.setResizeWeight(1.0);
//Disables the moving of divider
splitPane.setEnabled(false);
//splitPane.setDividerLocation(splitPane.getHeight());
//splitPane.setPreferredSize(new Dimension(640,400));
//Create the status area.
JPanel statusPane = new JPanel(new GridLayout(1,1));
CaretListenerLabel caretListenerLabel =
new CaretListenerLabel("Status: Ready");
statusPane.add(caretListenerLabel);
//Create the toolbar
JToolBar toolBar = new JToolBar();
toolBar.setFloatable(false);
toolBar.setRollover(true);
openButton = new JButton("Open Snort Ruleset");
toolBar.add(openButton);
saveButton = new JButton("Save Ruleset");
toolBar.add(saveButton);
toolBar.addSeparator();
aboutButton = new JButton("About");
toolBar.add(aboutButton);
//Add the components.
getContentPane().add(toolBar,BorderLayout.PAGE_START);
getContentPane().add(splitPane,BorderLayout.CENTER);
getContentPane().add(statusPane,BorderLayout.PAGE_END);
JMenu editMenu = createEditMenu();
JMenu styleMenu = createStyleMenu();
JMenuBar mb = new JMenuBar();
mb.add(editMenu);
mb.add(styleMenu);
setJMenuBar(mb);
//Put the initial text into the text pane.
//initDocument();
textPane.setCaretPosition(0);
//Start watching for undoable edits and caret changes.
textPane.addCaretListener(caretListenerLabel);
SwingUtilities.invokelater(new Runnable() {
public void run() {
textPane.requestFocusInWindow();
}
});
}
//This listens for and reports caret movements.
protected class CaretListenerLabel extends JLabel
implements CaretListener {
public CaretListenerLabel(String label) {
super(label);
}
//Might not be invoked from the event dispatch thread.
public void caretUpdate(CaretEvent e) {
caretInvoke(e.getDot(),e.getMark());
}
protected void caretInvoke(final int dot,final int mark) {
SwingUtilities.invokelater(new Runnable() {
public void run() {
try {
Rectangle caretCoords = textPane.modelToView(dot);
//Find suggestion
suggestionCombo@R_754_2419@.removeAllItems();
for (int i = 0; i < 5; i++) {
suggestionCombo@R_754_2419@.addItem(Integer.toString(i));
}
//suggestionCombo@R_754_2419@.setSelectedItem(null);
suggestionCombo@R_754_2419@.setEnabled(true);
suggestionLabel.setText("The following keywords are normally used as well. Click to use keyword(s). ");
//changeLog.setText("The following keywords are suggested to be used together: " + str);
} catch (BadLocationException ble) {
setText("caret: text position: " + dot + newline);
System.out.println("Bad Location Exception");
}
}
});
}
}
public class SuggestionCombo@R_754_2419@Listener implements ItemListener {
//public void actionPerformed(ActionEvent e) {
public void itemStateChanged(ItemEvent e) {
if (e.getStateChange() == ItemEvent.SELECTED) {
JCombo@R_754_2419@ cb = (JCombo@R_754_2419@)e.getSource();
String selection = (String) cb.getSelectedItem();
JOptionPane.showMessageDialog(null,"Item is selected","Information",JOptionPane.INFORMATION_MESSAGE);
}
}
}
/*
* Menu Creation
*/
//Create the edit menu.
protected JMenu createEditMenu() {
JMenu menu = new JMenu("Edit");
return menu;
}
protected JMenu createStyleMenu() {
JMenu menu = new JMenu("Style");
return menu;
}
private static void createAndShowGUI() {
//Create and set up the window.
final Temp frame = new Temp();
frame.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
//The standard main method.
public static void main(String[] args) {
//Schedule a job for the event dispatch thread:
//creating and showing this application's GUI.
SwingUtilities.invokelater(new Runnable() {
public void run() {
//Turn off Metal's use of bold fonts
UIManager.put("swing.boldMetal",Boolean.FALSE);
createAndShowGUI();
}
});
}
}
Solution
Before making any changes to the combo box, you need to delete the itemlistener and add it back when you are finished@ H_ 403_ 2 @ something like this:
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Insets;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import javax.swing.JCombo@R_754_2419@;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextPane;
import javax.swing.SwingUtilities;
import javax.swing.event.CaretEvent;
import javax.swing.event.CaretListener;
public class Suggestions {
private JFrame frame;
private JTextPane textPane;
private JCombo@R_754_2419@ suggestionCombo@R_754_2419@;
private SuggestionCombo@R_754_2419@Listener selectionListener;
public Suggestions() {
frame = new JFrame("Snort Ruleset IDE");
textPane = new JTextPane();
textPane.setCaretPosition(0);
textPane.setMargin(new Insets(5,5));
textPane.addCaretListener(new SuggestionCaretListener());
JScrollPane textEntryScrollPane = new JScrollPane(textPane);
textEntryScrollPane.setPreferredSize(new Dimension(300,400));
selectionListener = new SuggestionCombo@R_754_2419@Listener(frame);
suggestionCombo@R_754_2419@ = new JCombo@R_754_2419@();
suggestionCombo@R_754_2419@.setEditable(false);
suggestionCombo@R_754_2419@.setPreferredSize(new Dimension(25,25));
suggestionCombo@R_754_2419@.addItemListener(selectionListener);
JPanel suggestionPanel = new JPanel(new BorderLayout());
suggestionPanel.add(suggestionCombo@R_754_2419@,BorderLayout.PAGE_END);
frame.getContentPane().add(textEntryScrollPane,BorderLayout.NORTH);
frame.getContentPane().add(suggestionPanel,BorderLayout.soUTH);
frame.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
private final class SuggestionCaretListener implements CaretListener {
@Override
public void caretUpdate(CaretEvent e) {
SwingUtilities.invokelater(new Runnable() {
public void run() {
generateSuggestions();
}
});
}
}
public static final class SuggestionCombo@R_754_2419@Listener implements ItemListener {
Component parent;
public SuggestionCombo@R_754_2419@Listener(Component parent) {
this.parent = parent;
}
public void itemStateChanged(ItemEvent e) {
if (e.getStateChange() == ItemEvent.SELECTED) {
JCombo@R_754_2419@ cb = (JCombo@R_754_2419@) e.getSource();
String selection = (String) cb.getSelectedItem();
JOptionPane.showMessageDialog(parent,"The selected item is: " + selection,JOptionPane.INFORMATION_MESSAGE);
}
}
}
void generateSuggestions() {
suggestionCombo@R_754_2419@.removeItemListener(selectionListener);
suggestionCombo@R_754_2419@.removeAllItems();
for (int i = 0; i < 5; i++) {
suggestionCombo@R_754_2419@.addItem(Integer.toString(i));
}
suggestionCombo@R_754_2419@.setEnabled(true);
suggestionCombo@R_754_2419@.addItemListener(selectionListener);
}
public static void main(String[] args) {
new Suggestions();
}
}
The content of this article comes from the network collection of netizens. It is used as a learning reference. The copyright belongs to the original author.
THE END
二维码