Below is the answer specific to my original question, but if you're trying to achieve a similar structure in general, it'd probably be more practical follow camickr's method below. To do it the way I originally wanted, you have to override JPanel and implement Scrollable for the outer container.
(credit to user Kylar - JTextArea on JPanel inside JScrollPane does not resize properly)
import javax.swing.*;
import java.awt.*;
import javax.swing.text.*;
public class MyEditor extends JTextPane {
JFrame window;
JScrollPane editScroll;
NumberLines numPane;
HoldMe please;
public static void main(String args[]) {
new MyEditor();
}
MyEditor() {
setOpaque(false);
setEditorKit(new TextWrapKit());
numPane = new NumberLines();
numPane.setPreferredSize(new Dimension(50,100));
please = new HoldMe();
please.setLayout(new BorderLayout());
please.add(this,BorderLayout.CENTER);
please.add(numPane,BorderLayout.WEST);
editScroll = new JScrollPane(please);
editScroll.setPreferredSize(new Dimension(500,500));
editScroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
editScroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
window = new JFrame();
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.getContentPane().add(editScroll);
window.pack();
window.setVisible(true);
}
private class HoldMe extends JPanel implements Scrollable{
public Dimension getPreferredScrollableViewportSize() {
return super.getPreferredSize(); //tell the JScrollPane that we want to be our 'preferredSize' - but later, we'll say that vertically, it should scroll.
}
public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) {
return 16;//set to 16 because that's what you had in your code.
}
public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
return 16;//set to 16 because that's what you had set in your code.
}
public boolean getScrollableTracksViewportWidth() {
return true;//track the width, and re-size as needed.
}
public boolean getScrollableTracksViewportHeight() {
return false; //we don't want to track the height, because we want to scroll vertically.
}
}
private class NumberLines extends JPanel {
NumberLines() {
setBackground(new Color(120,120,120));
setOpaque(false);
repaint();
}
#Override
protected void paintComponent(Graphics g) {
g.fillRect(0,0,this.getWidth(),this.getHeight());
}
}
private class TextWrapKit extends StyledEditorKit {
ViewFactory defaultFactory=new TextWrapFactory();
public ViewFactory getViewFactory() {
return defaultFactory;
}
}
private class TextWrapFactory implements ViewFactory {
public View create(Element elem) {
String kind = elem.getName();
if (kind != null) {
if (kind.equals(AbstractDocument.ContentElementName)) {
return new TextWrapView(elem);
} else if (kind.equals(AbstractDocument.ParagraphElementName)) {
return new ParagraphView(elem);
} else if (kind.equals(AbstractDocument.SectionElementName)) {
return new BoxView(elem, View.Y_AXIS);
} else if (kind.equals(StyleConstants.ComponentElementName)) {
return new ComponentView(elem);
} else if (kind.equals(StyleConstants.IconElementName)) {
return new IconView(elem);
}
}
// default to text display
return new LabelView(elem);
}
}
private class TextWrapView extends LabelView {
public TextWrapView(Element elem) {
super(elem);
}
public float getMinimumSpan(int axis) {
switch (axis) {
case View.X_AXIS:
return 0;
case View.Y_AXIS:
return super.getMinimumSpan(axis);
default:
throw new IllegalArgumentException("Invalid axis: " + axis);
}
}
}
}
EDIT: code replaced with SCCE, sorry for the trouble
Okay, so it's structured like this...
• Top class - extends JTextPane
• Place this JTextPane into a JPanel set to BorderLayout CENTER
• Place another JPanel into the same JPanel set to WEST
• Place the JPanel holding the two into a JScrollPane
• Ready for deployment (nope)
Basically, I can't figure out a way to do this without losing out on something critical. I can get them all together, but I'll lose scrolling. Or I'll get scrolling back, but then lose text wrapping. One time I got wrapping, and technically it scrolled but not as it should have, in otherwords, the scrollpane didn't detect the size of the text. I need the nested JPanel (1st one) to scroll with the JTextPane
The problem area is in the constructor below, sorry it's such a mess but I'm losing it over here trying different things... Probably isn't helping. I'd be so grateful if somebody could help me figure this out.
Thank you for reading.
import javax.swing.*;
import java.awt.*;
import javax.swing.text.*;
import java.awt.BorderLayout;
public class MyEditor extends JTextPane {
JFrame window;
JScrollPane editScroll;
public static void main(String args[]) {
new MyEditor();
}
MyEditor() {
setOpaque(false);
setEditorKit(new TextWrapKit());
JPanel numPane = new JPanel();
JPanel packEdit = new JPanel();
packEdit.setLayout(new BorderLayout());
packEdit.add(this,BorderLayout.CENTER);
packEdit.add(numPane,BorderLayout.WEST);
editScroll = new JScrollPane(packEdit);
editScroll.setPreferredSize(new Dimension(500,500));
editScroll.setViewportView(packEdit);
editScroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
editScroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
window = new JFrame();
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.add(editScroll);
window.pack();
window.setVisible(true);
}
private class TextWrapKit extends StyledEditorKit {
ViewFactory defaultFactory=new TextWrapFactory();
public ViewFactory getViewFactory() {
return defaultFactory;
}
}
private class TextWrapFactory implements ViewFactory {
public View create(Element elem) {
String kind = elem.getName();
if (kind != null) {
if (kind.equals(AbstractDocument.ContentElementName)) {
return new TextWrapView(elem);
} else if (kind.equals(AbstractDocument.ParagraphElementName)) {
return new ParagraphView(elem);
} else if (kind.equals(AbstractDocument.SectionElementName)) {
return new BoxView(elem, View.Y_AXIS);
} else if (kind.equals(StyleConstants.ComponentElementName)) {
return new ComponentView(elem);
} else if (kind.equals(StyleConstants.IconElementName)) {
return new IconView(elem);
}
}
// default to text display
return new LabelView(elem);
}
}
private class TextWrapView extends LabelView {
public TextWrapView(Element elem) {
super(elem);
}
public float getMinimumSpan(int axis) {
switch (axis) {
case View.X_AXIS:
return 0;
case View.Y_AXIS:
return super.getMinimumSpan(axis);
default:
throw new IllegalArgumentException("Invalid axis: " + axis);
}
}
}
}
extends JTextPane
Why?
setEditorKit(new TextWrapKit());
Why?
Get the scroll pane working with the default components. Then if for some reason you still need to customize you make the changes one at a time to make sure it still works. If it doesn't work any more then you know what the problem is.
packEdit.add(numPane,BorderLayout.WEST);
Looks to me like you are trying to add line number. The standard way to do this is to add your component to the row header of the scrollpane, instead of making it part of the panel added to the viewport. See Text Component Line Number for an example of this approach.
In the future a SSCCE should be posted with every question. You get one free (attempted) answer without a SSCCE.
Related
I'm developing a Java Swing app for an award winning password protection system, and I need a large custom cursor [ 80 x 80 ], you might ask why so large, there is an online web demo you may look at to learn why it needs to be so large : http://gatecybertech.net
That large cursor is used on the login page in the above link. Of course you need to create a test password first before you can try the login process.
But anyway, in my Swing app, I hit a limit of 32 x 32 for the largest possible custom cursor, my code looks like the following :
Image cursorImage = toolkit.getImage("Cursor_Crosshair.PNG");
Tabular_Panel.setCursor(Toolkit.getDefaultToolkit().createCustomCursor(cursorImage,new Point(0,0),"custom cursor"));
The image size of Cursor_Crosshair.PNG is : 80 x 80
But what shows up in the screen is a shrinked version of it at : 32 x 32
So my question is : how can I bypass the size limit on customer cursor image, and make the cursor to show up at the size of 80 x 80 ?
I know the OS might be the reason for the limit, is there a way to overcome it ?
Here's my take on the glass pane painting approach. This is set up to behave pretty much like setting a custom cursor. The default "arrow" cursor is hidden while the custom cursor is shown, and the custom cursor is hidden when a component has some other cursor set, such as a text box.
Unfortunately, it ended up seeming to require quite a bit of Swing black magic, so I don't like it very much, but it does seem to work correctly. I've done a cursor like this before, but it was for something simpler, so I didn't run in to these issues.
Some of the problems I ran in to are:
The glass pane intercepts cursor changes (described e.g. on SO here). The only solution I've been able to find is to override Component.contains(int,int) to return false (described here, shown here), but why that works and doesn't seem to break anything else is mysterious.
Mouse exit events sometimes return a location inside the bounds of the component, so I don't think there's a reliable way to know when the mouse leaves the window except to use a timer.
package mcve;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import javax.imageio.*;
import java.net.*;
import java.io.*;
public class LargeCursor {
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
JFrame frame = new JFrame();
JPanel glass = new CustomGlassPane();
glass.add(new CursorPanel(), BorderLayout.CENTER);
frame.setGlassPane(glass);
// This next call is necessary because JFrame.setGlassPane delegates to the root pane:
// - https://docs.oracle.com/javase/9/docs/api/javax/swing/RootPaneContainer.html#setGlassPane-java.awt.Component-
// - http://hg.openjdk.java.net/jdk8/jdk8/jdk/file/687fd7c7986d/src/share/classes/javax/swing/JFrame.java#l738
// And JRootPane.setGlassPane may call setVisible(false):
// - https://docs.oracle.com/javase/9/docs/api/javax/swing/JRootPane.html#setGlassPane-java.awt.Component-
// - http://hg.openjdk.java.net/jdk8/jdk8/jdk/file/687fd7c7986d/src/share/classes/javax/swing/JRootPane.java#l663
glass.setVisible(true);
JPanel content = createTestPanel();
content.setCursor(BlankCursor.INSTANCE);
frame.setContentPane(content);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
});
}
static class CustomGlassPane extends JPanel {
CustomGlassPane() {
super(new BorderLayout());
super.setOpaque(false);
}
#Override
public boolean contains(int x, int y) {
return false;
}
}
static class CursorPanel extends JPanel {
final BufferedImage cursorImage;
Point mouseLocation;
CursorPanel() {
try {
cursorImage = createTransparentImage(
ImageIO.read(new URL("https://i.stack.imgur.com/9h2oI.png")));
} catch (IOException x) {
throw new UncheckedIOException(x);
}
setOpaque(false);
long mask = AWTEvent.MOUSE_EVENT_MASK | AWTEvent.MOUSE_MOTION_EVENT_MASK;
Toolkit.getDefaultToolkit().addAWTEventListener((AWTEvent e) -> {
switch (e.getID()) {
case MouseEvent.MOUSE_ENTERED:
case MouseEvent.MOUSE_EXITED:
case MouseEvent.MOUSE_MOVED:
case MouseEvent.MOUSE_DRAGGED:
capturePoint((MouseEvent) e);
break;
}
}, mask);
// This turned out to be necessary, because
// the 'mouse exit' events don't always have
// a Point location which is outside the pane.
Timer timer = new Timer(100, (ActionEvent e) -> {
if (mouseLocation != null) {
Point p = MouseInfo.getPointerInfo().getLocation();
SwingUtilities.convertPointFromScreen(p, this);
if (!contains(p)) {
setMouseLocation(null);
}
}
});
timer.setRepeats(true);
timer.start();
}
void capturePoint(MouseEvent e) {
Component comp = e.getComponent();
Point onThis = SwingUtilities.convertPoint(comp, e.getPoint(), this);
boolean drawCursor = contains(onThis);
if (drawCursor) {
Window window = SwingUtilities.windowForComponent(this);
if (window instanceof JFrame) {
Container content = ((JFrame) window).getContentPane();
Point onContent = SwingUtilities.convertPoint(comp, e.getPoint(), content);
Component deepest = SwingUtilities.getDeepestComponentAt(content, onContent.x, onContent.y);
if (deepest != null) {
if (deepest.getCursor() != BlankCursor.INSTANCE) {
drawCursor = false;
}
}
}
}
setMouseLocation(drawCursor ? onThis : null);
}
void setMouseLocation(Point mouseLocation) {
this.mouseLocation = mouseLocation;
repaint();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (mouseLocation != null) {
int x = mouseLocation.x - (cursorImage.getWidth() / 2);
int y = mouseLocation.y - (cursorImage.getHeight() / 2);
g.drawImage(cursorImage, x, y, this);
}
}
}
static final class BlankCursor {
static final Cursor INSTANCE =
Toolkit.getDefaultToolkit().createCustomCursor(
new BufferedImage(1, 1, BufferedImage.TYPE_INT_ARGB),
new Point(),
"BLANK");
}
static JPanel createTestPanel() {
JPanel panel = new JPanel(new GridLayout(3, 3));
panel.setBorder(BorderFactory.createEmptyBorder(100, 100, 100, 100));
for (int i = 0; i < 9; ++i) {
if ((i % 2) == 0) {
JTextField field = new JTextField("Text Field");
field.setHorizontalAlignment(JTextField.CENTER);
panel.add(field);
} else {
panel.add(new JButton("Button"));
}
}
return panel;
}
static BufferedImage createTransparentImage(BufferedImage img) {
BufferedImage copy =
GraphicsEnvironment.getLocalGraphicsEnvironment()
.getDefaultScreenDevice()
.getDefaultConfiguration()
.createCompatibleImage(img.getWidth(),
img.getHeight(),
Transparency.TRANSLUCENT);
for (int x = 0; x < img.getWidth(); ++x) {
for (int y = 0; y < img.getHeight(); ++y) {
int rgb = img.getRGB(x, y) & 0x00FFFFFF;
int bright = (((rgb >> 16) & 0xFF) + ((rgb >> 8) & 0xFF) + (rgb & 0xFF)) / 3;
int alpha = 255 - bright;
copy.setRGB(x, y, (alpha << 24) | rgb);
}
}
return copy;
}
}
OK, after some research and modification, I found the answer :
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.*;
import javax.imageio.*;
import javax.swing.event.MouseInputAdapter;
public class Demo_Large_Custom_Cursor
{
static private MyGlassPane myGlassPane;
// Create the GUI and show it. For thread safety, this method should be invoked from the event-dispatching thread.
private static void createAndShowGUI()
{
//Create and set up the window.
JFrame frame=new JFrame("Demo_Large_Custom_Cursor");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Start creating and adding components.
JCheckBox changeButton=new JCheckBox("Custom Cursor \"visible\"");
changeButton.setSelected(false);
//Set up the content pane, where the "main GUI" lives.
Container contentPane=frame.getContentPane();
contentPane.setLayout(new FlowLayout());
contentPane.add(changeButton);
JButton Button_1=new JButton("<Html><Table Cellpadding=7><Tr><Td>A</Td><Td>B</Td></Tr><Tr><Td>C</Td><Td>D</Td></Tr></Table></Html>");
Button_1.setPreferredSize(new Dimension(80,80));
Button_1.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent evt) { Out("Button 1"); } });
contentPane.add(Button_1);
JButton Button_2=new JButton("<Html><Table Cellpadding=7><Tr><Td>1</Td><Td>2</Td></Tr><Tr><Td>3</Td><Td>4</Td></Tr></Table></Html>");
Button_2.setPreferredSize(new Dimension(80,80));
Button_2.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent evt) { Out("Button 2"); } });
contentPane.add(Button_2);
//Set up the menu bar, which appears above the content pane.
JMenuBar menuBar=new JMenuBar();
JMenu menu=new JMenu("Menu");
menu.add(new JMenuItem("Do nothing"));
menuBar.add(menu);
frame.setJMenuBar(menuBar);
//Set up the glass pane, which appears over both menu bar
//and content pane and is an item listener on the change
//button.
myGlassPane=new MyGlassPane(changeButton,menuBar,frame.getContentPane());
changeButton.addItemListener(myGlassPane);
frame.setGlassPane(myGlassPane);
//Show the window.
frame.setLocationRelativeTo(null);
frame.pack();
frame.setVisible(true);
}
private static void out(String message) { System.out.print(message); }
private static void Out(String message) { System.out.println(message); }
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();
}
});
}
}
/**
We have to provide our own glass pane so that it can paint.
*/
class MyGlassPane extends JComponent implements ItemListener
{
Point point;
//React to change button clicks.
public void itemStateChanged(ItemEvent e)
{
setVisible(e.getStateChange()==ItemEvent.SELECTED);
}
protected void paintComponent(Graphics g)
{
try
{
if (point!=null)
{
// g.setColor(Color.red);
// g.fillOval(point.x-10,point.y-10,20,20);
BufferedImage image=ImageIO.read(new File("C:/Cursor_Crosshair.PNG"));
g.drawImage(image,point.x-39,point.y-39,null);
}
}
catch (Exception e) { }
}
public void setPoint(Point p)
{
point=p;
}
public MyGlassPane(AbstractButton aButton,JMenuBar menuBar,Container contentPane)
{
CBListener listener=new CBListener(aButton,menuBar,this,contentPane);
addMouseListener(listener);
addMouseMotionListener(listener);
}
}
/**
Listen for all events that our check box is likely to be interested in. Redispatch them to the check box.
*/
class CBListener extends MouseInputAdapter
{
Toolkit toolkit;
Component liveButton;
JMenuBar menuBar;
MyGlassPane glassPane;
Container contentPane;
public CBListener(Component liveButton,JMenuBar menuBar,MyGlassPane glassPane,Container contentPane)
{
toolkit=Toolkit.getDefaultToolkit();
this.liveButton=liveButton;
this.menuBar=menuBar;
this.glassPane=glassPane;
this.contentPane=contentPane;
}
public void mouseMoved(MouseEvent e)
{
// redispatchMouseEvent(e,false);
redispatchMouseEvent(e,true);
}
public void mouseDragged(MouseEvent e)
{
redispatchMouseEvent(e,false);
}
public void mouseClicked(MouseEvent e)
{
redispatchMouseEvent(e,false);
}
public void mouseEntered(MouseEvent e)
{
redispatchMouseEvent(e,false);
}
public void mouseExited(MouseEvent e)
{
redispatchMouseEvent(e,false);
}
public void mousePressed(MouseEvent e)
{
redispatchMouseEvent(e,false);
}
public void mouseReleased(MouseEvent e)
{
redispatchMouseEvent(e,true);
}
//A basic implementation of redispatching events.
private void redispatchMouseEvent(MouseEvent e,boolean repaint)
{
Point glassPanePoint=e.getPoint();
Container container=contentPane;
Point containerPoint=SwingUtilities.convertPoint(glassPane,glassPanePoint,contentPane);
if (containerPoint.y<0)
{ //we're not in the content pane
if (containerPoint.y+menuBar.getHeight()>=0)
{
//The mouse event is over the menu bar.
//Could handle specially.
}
else
{
//The mouse event is over non-system window
//decorations, such as the ones provided by
//the Java look and feel.
//Could handle specially.
}
}
else
{
//The mouse event is probably over the content pane.
//Find out exactly which component it's over.
Component component=SwingUtilities.getDeepestComponentAt(container,containerPoint.x,containerPoint.y);
// if ((component!=null) && (component.equals(liveButton)))
if ((component!=null))
{
//Forward events over the check box.
Point componentPoint=SwingUtilities.convertPoint(glassPane,glassPanePoint,component);
component.dispatchEvent(new MouseEvent(component,e.getID(),e.getWhen(),e.getModifiers(),componentPoint.x,componentPoint.y,e.getClickCount(),e.isPopupTrigger()));
}
}
//Update the glass pane if requested.
if (repaint)
{
glassPane.setPoint(glassPanePoint);
glassPane.repaint();
}
}
}
And the Cursor_Crosshair.PNG is like this :
i have a program with a frame that contains a main panel with the cardlayout layout, and i want it to display different cards/panel.
In my case i'm really struggling to call a new card from a button action listener.
I want a new card to appear after i click on a button but none of the codes i put in my action listener displayed the card i wanted.
I know my actionListener work because i did a println inside.
here's my code. i got rid of anything that was unnecessary so it's easier to read. Thanks for the help!
i'll take all advices about code structuration
the mainFrame :
public class MainFrame extends JFrame{
final static String CONNEXION_VIEW = "connexionView";
final static String CONNEXION_FAILED_VIEW = "connexionRefusee";
public MainFrame()
{
super();
initialize();
}
private void initialize()
{
getMainPanel();
add(getMainPanel());
}
CardLayout cardLayout;
public CardLayout getCardLayout()
{
if (cardLayout == null)
{
cardLayout = new CardLayout();
}
return cardLayout;
}
JPanel mainPanel;
public JPanel getMainPanel()
{
if (mainPanel == null)
{
mainPanel = new JPanel();
mainPanel.setLayout(getCardLayout());
mainPanel.add(CONNEXION_VIEW, getConnexionView());
mainPanel.add(CONNEXION_FAILED_VIEW, getConnexionFailedView());
}
return mainPanel;
}
ConnexionView connexionView;
protected ConnexionView getConnexionView()
{
if (connexionView == null)
{
connexionView = new ConnexionView();
}
return connexionView;
}
ConnexionFailedView connexionFailedView;
protected ConnexionFailedView getConnexionFailedView()
{
if (connexionFailedView == null)
{
connexionFailedView = new ConnexionFailedView();
}
return connexionFailedView;
}
the connexion view, the one with the button to click with the action listener where i want to put my code
public class ConnexionView extends JPanel{
GridBagLayout gbl = new GridBagLayout();
private JButton btnConnexion;
Dimension dimensionBouton = new Dimension(170, 30);
public ConnexionView()
{
super();
initialise();
}
private void initialise()
{
setLayout(gbl);
GridBagConstraints gbcbtnConnexion = new GridBagConstraints();
gbcbtnConnexion.gridwidth = GridBagConstraints.REMAINDER;
gbcbtnConnexion.gridheight = GridBagConstraints.REMAINDER;
gbcbtnConnexion.gridx = 1;
gbcbtnConnexion.gridy = 2;
add(getBtnConnexion(), gbcbtnConnexion);
}
private JButton getBtnConnexion()
{
if (btnConnexion == null)
{
btnConnexion = new JButton("Connexion");
btnConnexion.setPreferredSize(dimensionBouton);
btnConnexion.setMinimumSize(dimensionBouton);
btnConnexion.addMouseListener(new MouseAdapter()
{
#Override
public void mouseClicked(MouseEvent e)
{
/////code to display the connexion_Failed_View
System.out.println("test");
}
});
}
return btnConnexion;
}
}
and the connexion failed view, the one i want to display after the button is clicked
public class ConnexionFailedView extends JPanel{
public ConnexionFailedView()
{
super();
initialise();
}
private void initialise()
{
setBackground(Color.YELLOW);
}
thanks in advance
You will need to keep the component in your Button somehow, so you can access it.
class ConnexionView {
private JComponent mainPanel;
public ConnexionView(JComponent mp) { mainPanel = mp; }
}
Obviously, that means the MainFrame needs to pass it then.
Now, the listener can do
// it would be cleaner if you passed the layout in the constructor as well
CardLayout cl = (CardLayout) mainPanel.getLayoutManager();
cl.show(mainPanel, MainFrame.CONNEXION_FAILED_VIEW);
I'm programming in Java, trying to use a cardholder in order to switch between 2 JPanels which are each an extension of their own class. I think I understand the basic concepts but I am having errors in my current revision, when calling the classes. I'm getting a null pointer exception and I think it's a structural problem but I'm not sure how or why.
The main method points to this class
public class Skeleton implements ActionListener{
JPanel cardHolder;
CardLayout cards;
String cardA = "A";
String cardB = "B";
JPanel Jboard;
JPanel Jmenu;
JFrame frame2;
Board board;
Menu menu;
boolean menuSet;
boolean boardSet;
Timer timer;
public class Switcher implements ActionListener{
String card;
Switcher(String card){
this.card = card;
}
#Override
public void actionPerformed(ActionEvent e) {
cards.show(cardHolder, card);
}
}
public Skeleton(JFrame frame){
JPanel menu = new Menu();
JPanel board = new Board();
JFrame frame2 = frame;
timer = new Timer(5, this);
timer.start();
cardHolder = new JPanel();
cards = new CardLayout();
cardHolder.setLayout(cards);
cardHolder.add(menu, cardA);
cardHolder.add(board, cardB);
frame2.add(cardHolder);
frame2.revalidate();
frame2.setVisible(true);
}
public JFrame getSkeleton(){
return frame2;
}
public JPanel getCardHolder(){
return cardHolder;
}
public void checkStatus(){
if (menuSet == true){
new Switcher(cardB);
boardSet = false;
}
if (boardSet == true){
new Switcher(cardA);
menuSet = false;
}
}
#Override
public void actionPerformed(ActionEvent e) {
menuSet = menu.getMenuset();
boardSet = board.getBoardset();
checkStatus();
}
}
This is the board class, one of the JPanels I'm trying to switch between
public class Board extends JPanel{
boolean boardset;
Menu menu = new Menu();
public Board(){
setBackground(Color.WHITE);
}
public JPanel getPanel(){
return this;
}
public void setBoardset(boolean x){
boardset = x;
}
public boolean getBoardset(){
return boardset;
}
}
Here is the other JPanel class, which contains a button used to switch to the other JPanel class. This is also the original starting JPanel used.
public class Menu extends JPanel implements ActionListener{
boolean menuset;
public Menu(){
setBackground(Color.BLACK);
JButton button = new JButton("hello");
button.addActionListener(this);
this.add(button);
}
public JPanel getPanel(){
return this;
}
#Override
public void actionPerformed(ActionEvent e) {
menuset = true;
}
public void setMenuset(boolean x){
menuset = x;
}
public boolean getMenuset(){
return menuset;
}
}
Like I said, I'm getting a null pointer exception. It is occuring on this line of the Skeleton() class
menuSet = menu.getMenuset();
The line above is right after the actionPerformed event above (from the timer), and I have tested the timer a little, it works doing basic print statements but whenever I try to use the 'menu' or 'board' instance inside the actionPerformed, I get this null pointer exception.
I would appreciate any advice. I get the idea that the way I'm doing this may be a little convoluted. If anyone has any suggestions on a better way to do this it would also be helpful. My main goal is to be able to call 2 separate classes from one main class containing a cardholder. That way I can separate the code in order to keep everything isolated and in order.
Your Skeleton class has a "menu" member but it isn't set anywhere that I can see. The constructor declares its own "menu" local variable, which is local to the constructor and hides the member. Setting "menu" inside the constructor won't set the member. I don't see anywhere else where the "menu" member is set, unless I've missed something or unless another class in the same package is setting it.
how do you trap the event before the new tab is switched to?
In every Tab I have JTable and i do something with it's data(delete, add , update). I would like to do data validation(save or cancel changes) before switching to the new tab. I use Java 1.5.
class ViewPanel extends JPanel
{
private void Components() {
setPreferredSize(new Dimension(700, 400));
tabbedPane.addTab("DC", ANSFER.getIcon(),new DcTabPanel(this), "DC");
tabbedPane.addTab("PC", THUMB4.getIcon(),new PcTabPanel(this), "PC");
tabbedPane.addChangeListener(this);
add(tabbedPane);
}
public void stateChanged(ChangeEvent e) {
}
}
JTabbedPane is backed by a SingleSelectionModel. If you extend DefaultSingleSelectionModel, you can override the setSelectedIndex method and implement your logic.
// in new selection model:
public void setSelectedIndex(int index) {
// do pre-switch things here
super.setSelectedIndex(index);
}
// in ViewPanel, on tabbedPane create:
tabbedPane.setModel(newSelectionModel);
The reason you can't simply use a ChangeListener is because that fires on change. By extending the selection model, you fire before the tab change.
You can prevent tab switching by extending JTabbedPane and override setSelectedIndex(int). Here is a small example illustrating that. It simply prevents from switching between non-contiguous tabs:
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTabbedPane;
import javax.swing.SwingUtilities;
public class Test2 {
private static class BlockingTabbedPane extends JTabbedPane {
public static interface TabSwitchAllower {
public boolean allowTabSwitch(int from, int to);
}
private TabSwitchAllower allower;
public BlockingTabbedPane(TabSwitchAllower allower) {
super();
this.allower = allower;
}
#Override
public void setSelectedIndex(int index) {
if (allower == null || allower.allowTabSwitch(getSelectedIndex(), index)) {
super.setSelectedIndex(index);
}
}
}
protected static void initUI() {
final JFrame frame = new JFrame("test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
BlockingTabbedPane.TabSwitchAllower allower = new BlockingTabbedPane.TabSwitchAllower() {
#Override
public boolean allowTabSwitch(int from, int to) {
if (Math.abs(from - to) == 1) {
return true;
} else {
JOptionPane.showMessageDialog(frame, "You can only switch between contiguous tabs");
}
return false;
}
};
JTabbedPane tabbedPane = new BlockingTabbedPane(allower);
for (int i = 0; i < 10; i++) {
tabbedPane.addTab("Tab-" + i, new JLabel("Hello tab " + i));
}
frame.add(tabbedPane);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
initUI();
}
});
}
}
java actionlistener on a tab
How to Write a Change Listener (Oracle Docs)
JTabbedPane API (Oracle Docs)
Those two links should help you out. I haven't really worked with tabbedPanes, but I am assuming that the getSelectedComponent() will return the current selected tab. So you can have a handle to the currentTab which will be set during instantiation. Then you can have something like this.
class TabListener implements ChangeListener {
public void stateChanged(ChangeEvent e) {
// Replace JSlider with whatever your tab's data type is
JSlider source = (JSlider)e.getSource();
// Use the 'currentTab' handle to do what you want.
currentTab = getSelectedComponent();
// I'm assuming that the 'selected component' by the time this stuff
// runs is going to be the new selected tab.
}
}
I am not too confident about my answer, but I certainly hope that this will point you towards the right direction! Please say if you need any clarification or anything! If I happen to discover anything that I think might be useful, I'll be certain to edit my answer!
I am trying to change JList rows dynamically. I need change nth row colour, highlight it(n is unknown during compilation). I saw a lot of examples with custom ListCellRenderer, but all were "static".
In other words I have JList with x rows. During runtime my "business logic" detects nth row is important. So I want make its background green, wait one second, and then make it white again. One more thing, don't wan change row selection.
What is the best way to do so?
Simple, set a custom ListCellRenderer to your JList using:
list.setCellRenderer(myListCellrenderer);
Now inside the overridden method getListCellRendererComponent() do something like this:
public Component getListCellRendererComponent(.....) {
Component c = super.getListCellRendererComponent();
c.setBackGround(Color.blue)
return c;
}
The above example assumed that your custom renderer overrid DefaultListCellRenderer
Based on ListDemo sample from SUN.
If you enter some text in the textfield which isn't in the list and you hit highlight it gets added.
If the text is in the list and you hit highlight the entry in the list gets temporarily highlighted blue.
Note the solution here with the match field is just for demo. For more correct implementation consider the other ideas proposed and consider using javax.swing.Timer
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class ListDemo extends JPanel {
private JList list;
private DefaultListModel listModel;
public String match = null;
private static final String hireString = "Highlight";
private JTextField employeeName;
public ListDemo() {
super(new BorderLayout());
listModel = new DefaultListModel();
listModel.addElement("Test1");
listModel.addElement("Test2");
listModel.addElement("Test3");
list = new JList(listModel);
list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
list.setSelectedIndex(0);
list.setVisibleRowCount(5);
list.setCellRenderer(new MyListCellRenderer());
JScrollPane listScrollPane = new JScrollPane(list);
JButton hireButton = new JButton(hireString);
HireListener hireListener = new HireListener(hireButton);
hireButton.setActionCommand(hireString);
hireButton.addActionListener(hireListener);
hireButton.setEnabled(false);
employeeName = new JTextField(10);
employeeName.addActionListener(hireListener);
employeeName.getDocument().addDocumentListener(hireListener);
listModel.getElementAt(list.getSelectedIndex()).toString();
JPanel buttonPane = new JPanel();
buttonPane.setLayout(new BoxLayout(buttonPane,
BoxLayout.LINE_AXIS));
buttonPane.add(Box.createHorizontalStrut(5));
buttonPane.add(employeeName);
buttonPane.add(hireButton);
buttonPane.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
add(listScrollPane, BorderLayout.CENTER);
add(buttonPane, BorderLayout.PAGE_END);
}
class MyListCellRenderer extends JLabel implements ListCellRenderer {
public MyListCellRenderer() {
setOpaque(true);
}
public Component getListCellRendererComponent(JList paramlist, Object value, int index, boolean isSelected, boolean cellHasFocus) {
setText(value.toString());
if (value.toString().equals(match)) {
setBackground(Color.BLUE);
SwingWorker worker = new SwingWorker() {
#Override
public Object doInBackground() {
try {
Thread.sleep(5000);
} catch (InterruptedException e) { /*Who cares*/ }
return null;
}
#Override
public void done() {
match = null;
list.repaint();
}
};
worker.execute();
} else
setBackground(Color.RED);
return this;
}
}
class HireListener implements ActionListener, DocumentListener {
private boolean alreadyEnabled = false;
private JButton button;
public HireListener(JButton button) {
this.button = button;
}
public void actionPerformed(ActionEvent e) {
String name = employeeName.getText();
if (listModel.contains(name)) {
match = name;
list.repaint();
employeeName.requestFocusInWindow();
employeeName.selectAll();
return;
}
if (name.equals("")) {
Toolkit.getDefaultToolkit().beep();
employeeName.requestFocusInWindow();
employeeName.selectAll();
return;
}
int index = list.getSelectedIndex();
if (index == -1)
index = 0;
else
index++;
listModel.insertElementAt(employeeName.getText(), index);
employeeName.requestFocusInWindow();
employeeName.setText("");
list.setSelectedIndex(index);
list.ensureIndexIsVisible(index);
}
public void insertUpdate(DocumentEvent e) {
enableButton();
}
public void removeUpdate(DocumentEvent e) {
handleEmptyTextField(e);
}
public void changedUpdate(DocumentEvent e) {
if (!handleEmptyTextField(e))
enableButton();
}
private void enableButton() {
if (!alreadyEnabled)
button.setEnabled(true);
}
private boolean handleEmptyTextField(DocumentEvent e) {
if (e.getDocument().getLength() <= 0) {
button.setEnabled(false);
alreadyEnabled = false;
return true;
}
return false;
}
}
private static void createAndShowGUI() {
JFrame frame = new JFrame("ListDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JComponent newContentPane = new ListDemo();
newContentPane.setOpaque(true);
frame.setContentPane(newContentPane);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() { createAndShowGUI(); }
});
}
}
Your custom ListCellRenderer, which implements the method getListCellRendererComponent, will have access to both the JList and the value that it is redering. This gives you a couple options for how to determine when to paint the nth row green:
You could subclass JList and have the renderer ask it which color to use for the bg. The JList subclass could trigger a repaint when the business logic determines that it is time for the nth row to be green, and then start an Swing Timer to trigger a repaint returning the bg back to normal
When the business logic determines when you should show the row as green, you also have the option of setting state on the backing object of the row, and test it for that state within getListCellRendererComponent, setting the bg green if the state is correct. Again, you have the option of setting an Swing Timer to revert the state on the backing object.