We Keep Coding

Panel background not being changed by UI manager

In my program I would like the user to be able to change the colour scheme of the program. I have a method which passes in a colour to set the background of all the panels using UIManager.
public void changeColourScheme(Color c) {
UIManager.put("Panel.background", c);
SwingUtilities.updateComponentTreeUI(this);
}
However the issue I'm running into is that it is not changing the colour of the panels. This method is located in the class for the JFrame.

Copied directly from Swing API Docs.
public static void updateComponentTreeUI(Component c)
A simple minded look and feel change: ask each node in the tree
to updateUI() -- that is, to initialize its UI property with the
current look and feel.
Notice the emphasize. Your code doesn't work because you are passing this as the argument to updateComponentTreeUI(). Since you are passing your panel as the argument, only the components inside the panel and the panel itself will get their UI updated. You have to pass the container that holds all other panels in your program, that is your JFrame
public void changeColourScheme(Color c) {
UIManager.put("Panel.background", c);
SwingUtilities.updateComponentTreeUI(frame); //instace of your frame
}

simply because the UIDefaults changes is only effective for the newly created components
for your feature to work you have to make the app restart then before starting the gui change the background in the defaults in the UIManager , or you will have to do it manually (panel by panel).
if you do it manually recursion will help a lot ,like this
private static void loopForPanel(Container c, Color col) {
synchronized (c.getTreeLock()) {
for (Component com : c.getComponents()) {
if (com instanceof JPanel) {
com.setBackground(col);
}
if (com instanceof Container) {
loopForPanel((Container) com,col);
}
}
}
}
then in your changeColourScheme method pass the frame it self for the loopForPanel method with your desired color.

Why isn't anything being drawn to my JPanel?

Since I'm new I can't post more than two links, but this is an x-post from reddit.com/r/learnprogramming, just for full disclosure.
I'll basically just be pasting what I said there to here. Thanks for your help, if you can help.
I'm writing somewhat of a graphing application. I currently only have it able to graph sin(x), but that's not the point of this question. I am not able to draw to my main panel. Here is what it currently looks like.
I had an overridden paint function in my Window.java class, which drew the sin(x) function and the axes, but when I made an inner class which extended JPanel(), it would no longer draw.
I then tried to make a separate file, but that didn't draw anything either.
What could be preventing it from drawing?
Here are all my files in question.
edit: code in question:
GraphDraw.java:
//import stuff
Public class GraphDraw extends JPanel {
SinX sinx = new SinX();
GraphPanel p = new GraphPanel();
#Override
public void paintComponent(Graphics gc) {
super.paintComponent(gc);
Graphics2D g = gc;
p.paintComponent(g);
sinx.paint(g);
}
}
And in Window.java, I initialize GraphDraw and add it to my main panel, which is underneath the buttons in the picture and above the x/y min/max labels.
GraphDraw drawer = new GraphDraw();
/*
GUI code
*/
mainPanel.add(drawer);
SinX.java
//import stuff
public class SinX extends Component {
public void paint(Graphics g) {
g.setColor(Color.red);
for(double x=-400;x<=400;x=x+0.5) {
double y = 50 * sin(x*((Math.PI)/180));
int Y = (int)y;
int X = (int)x;
g.drawLine(400+X,300-Y,400+X,300-Y);
}
}
}

First, before anything else, do the following:
Change you object from Component to JComponent
Do not ever, ever call paintComponent() or paint() on a graphics object from swing or awt, use object.repaint(); (For reasons I won't go into here, because it's long and complicated)
From there I would try calling setVisible(true); on all your objects. If you are getting this code from a tutorial, then stop and use a different tutorial. You need to learn how swing and the AWT library work before you can start making user interfaces. Nobody uses AWT anymore because Swing is much better. For reasons why, look at the following page. If you are too lazy to do that, its because it's more optimized and more powerful.
What is the difference between Swing and AWT?

Is there a way to disable all buttons with a method?

This is a lab for school that I'm struggling with, the code is making a game of hangman, and when the "brain" program says the game is over, all of the letter buttons are supposed to be disabled.
relevant code sections:
the buttons:
class ActionButton extends JButton implements ActionListener{
private String name;
private char t;
public ActionButton(String s){
super(s);
name = s;
t = name.charAt(0);
}
#Override
public void actionPerformed(ActionEvent e) {
ido.newLetter(t);
this.setEnabled(false);
LovesMePanel.this.update();
}
}
the update method:
public void update(){
answers = ido.getAnswer();
flower.setTriesLeft(ido.getTriesLeft());
progress.setText(answers);
if(ido.gameOver()){
// This is where I need to deactivate the buttons
if(ido.hasWon()){
}
}
else if(triesLeft == 0){
}
}
the buttons are all created in a loop in the LoveMePanel that holds all of the other panels. Is there a way to reference them all or disable them all when the game is over?
If not, how should I change my code so that it would be possible to do that?

If you put your buttons in a Collection, you can iterate through them and disable them all that way. I.e.,
for (JButton b : myButtons) {
b.setEnabled(false)
}
If not, you have 26 disable statements to write.

See the setEnabled() method for JButton. You can:
Add your Buttons to an ArrayList while creating them and then iterate over it and disable one by one
Get children of a JPanel, iterate over them, check if it's a button and disable it
Put a Glass Pane on top of your Burrons to intercept the incoming events
Feel free to choose the one you like best.

how about getting the children of the root panel by calling getComponents and iterating over them recursively and finding JButtons and disabling them as you find them?

How do I add a MouseListener to a graphics object inside another graphics object?

I'm working on a GUI for a card game and am using the ACM's student graphics library for the sake of familiarity. I have written a program that draws my solitaire game to the screen, and am having trouble making it interactive.
Background:
There are a lot of classes here, and I'll do my best to describe them each.
Top level JFrame containing the application.
GCanvas (that holds all the graphics objects)
SolitaireGameControl (GCompound holding all the other GCompounds making up the solitaire game)
Array of PileViews, a pile of cards (GCompound consisting of an array of Cards)
Cards (GCompound consisting of rectangles and labels)
(GCompound: a collection of graphics objects treated as one object. (If car was a GCompound, it would have GOval[] wheels, GRect body and so when I add it to the canvas, it displays as one object))
A card as seen from the top-level class would look like a bit like this: jFrame.gCanvas.solitaireGameControl.pileViews[pile number].cardView
What I've been trying to do is add a MouseListener to every single card, so that when a card is clicked and a MouseEvent is fired, MouseEvent e.getSource() = the card that was clicked.
Here's how it looks now:
public SolitaireGameControl(SolitaireGame game) {
this.game = game; // Model of the game.
this.pileViews = PileView.getPileViews(game.drawPiles); // ArrayList of PileViews (the pile of cards)
for(PileView pv : pileViews) {
for(CardView cv : pv.cardViews) {
cv.addMouseListener(this); // add a mouseListener to the card
}
}
this.addMouseListener(this); // if I don't include this, nothing happens when I click anything. If I do include this, this whole object is the source.
}
#Override
public void mouseClicked(MouseEvent e) {
System.out.println(e.getSource()); // should return the card I clicked.
}
When I run this program, the source of every event is SolitaireGameControl, granted I leave in the this.addMouseListener(this);. If I take out this statement, nothing is printed at all, leading me to believe that the mouseListeners I have added are only working one level deep. (The first GCompound on the canvas, not the GCompounds inside it.)
Therefore, my question is as follows: Is there a way to get a MouseListener for a GCompound inside of a GCompound inside of a GCompound, and have MouseEvent's getSource to correctly identify the card? If not, is there a way to restructure my program to make it work as intended? (I know I should really be using a better graphics library for starters.)

That would make sense. From my experience, if I put some components inside a top-level container, the container is the one that receives input events.
Have you tried an approach where you do something like:
/* This is the mouse listener for the top-level container. */
#Override
public void mouseClicked(MouseEvent e) {
for(PileView pv : pileViews) {
for(CardView cv : pv.cardViews) {
if(cv.getBounds().contains(e.getPoint())) {
cv.dispatchEvent(e);
}
}
}
}
... and then handle mouse clicks on a 'CardView' level normally.
When the top-level container receives a mouse event, it checks if the mouse interacted with a card based on the location of the event (if the card's area contains the point). If it did, it passes down the mouse event to the card's mouse listener.
I'm assuming that the elements near the beginning of 'pv.cardViews' are the cards that are more to the front.

How to access multiple JPanels inside JFrame?

I have a JFrame that contains a "display" JPanel with JTextField and a "control" JPanel with buttons that should access the contents of the display JPanel. I think my problem is related on how to use the observer pattern, which in principle I understand. You need to place listeners and update messages, but I don't have a clue where to put these, how to get access from one panel to the other and maybe if necessary to introduce a "datamodel" class. For example, I want to access the contents of the JTextField from the control panel and I use an anonymous action listener as follows:
JButton openfile = new JButton("Convert file");
openfile.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
openButtonPressed();
}
});

You need to reduce the coupling between these objects.
You can have a master object, that owns all the text fields and the button ( the panels are irrelevant )
Then a separete actionlistener within that master object ( I call it mediator see mediator pattern )
That action listener performs a method on the mediator which in turn take the values from the textfields and create perhaps a transfer object.
This way you reduce the coupling between the panels, textfields etc. and let the control in one place ( the mediator ) that is, you don't let them know each other.
You can take a look at the code in this question:
https://stackoverflow.com/questions/324554/#324559
It shows these concepts in running code.
BTW the observer pattern is already implemented in the JTextField, JButton, ActionListener etc. You just need to add the hooks.
I hope this helps.
EDIT Joined two answers into one.
This is the code.
class App { // this is the mediator
// GUI components.
private JFrame frame;
private JTextField name;
private JTextField count;
private JTextField date;
// Result is displayed here.
private JTextArea textArea;
// Fired by this button.
private JButton go;
private ActionListener actionListener;
public App(){
actionListener = new ActionListener(){
public void actionPerformed( ActionEvent e ){
okButtonPressed();
}
};
}
private void okButtonPressed(){
// template is an object irrelevant to this code.
template.setData( getData() );
textArea.setText( template.getTransformedData() );
}
public void initialize(){
frame = new JFrame("Code challenge v0.1");
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
name = new JTextField();
count = new JTextField();
date = new JTextField();
textArea = new JTextArea();
go = new JButton("Go");
go.addActionListener( actionListener ); // prepare the button.
layoutComponents(); // a lot of panels are created here. Irrelevant.
}
}
Complete and running code can be retrieved here:
It is important to favor composition over inheritance when possible.

It does make the code cleaner if you create the models in one layer and add a layer or two above to create the components and layout. Certainly do not extend the likes of JFrame and JPanel.
Do not feel the need to make the composition hierarchy in the model layer exactly match the display. Then it's just a matter of taking the text from the Document and performing the relevant operation.
Okay, perhpas not that simple. Swing models are a little bit messy. In particular ButtonModel is brain damaged, and the controller area of code might not be entirely pure.

We have so called builders, which will build the parent panel out of the children. In this builder you will have access to all the subcomponents you need to listen to and can thus can implement any logic there.
Finally the builder will then return the parent panel with the complete logic.
Once you've got the parent panel it's really a mess getting to the child components and have them do anything.

thanks. I added a datamodel layer which handles somehow the communication between the panels.
I also found this link on Listeners on JTextField usefull:
link text