We Keep Coding

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?

JList value changes when clicked

New to the forum and to Java. I am trying to have my JList respond when double-clicked, which I have accomplished. The JList is being populated by a SQL query which is ran when a button in the GUI is pressed. Based on the SQL query, the JList is populated, this is also working.
The issue comes about if I try to update the JList by clicking the button to query SQL again. When I click that, the change initially shows up in the JList, however when I click on that option in the JList it immediately switches back to what it was initially. When I double-click on what appears to be the incorrect name, the value that I have printing in the console reports correctly. So it has the value correct in the console but the rendering in the JList is not correct.
I appreciate any responses, I have combed the forums without any luck. I am new to Java so I'm sure there is quite a bit that isn't perfect with my code. Code is below please let me know if you need more. Thank you.
public JPanel results(StringBuilder message)
{
StringBuilder[] options = {message};
showOption = new JList(options);
showOption.setLocation(300, 50);
showOption.setSize(140,100);
showOption.setVisibleRowCount(10);
textPanel.add(showOption);
showOption.revalidate();
showOption.repaint();
MouseListener mouseListener = new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
//JList showOption = (JList) mouseEvent.getSource();
if (e.getClickCount() == 2) {
int index = showOption.locationToIndex(e.getPoint());
Object o = showOption.getModel().getElementAt(index);
System.out.println("Double-clicked on: " + o.toString());
}
}
};
showOption.addMouseListener(mouseListener);
return totalGUI;
}
public static void main ( String args[] )
{
//JFrame.setDefaultLookAndFeelDecorated(true);
JFrame frame = new JFrame("[=] JTextField of Dreams [=]");
GUI_TextField demo = new GUI_TextField();
frame.setContentPane(demo.createContentPane());
//frame.setContentPane(demo.results(message));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(510, 400);
frame.setVisible(true);
}

Three things jump out at me immediately.
You're creating a new JList each time
You're manually setting the size and position of the JList
You're not removing the previous JList
For example...
public JPanel results(StringBuilder message)
{
StringBuilder[] options = {message};
// Create new JList
showOption = new JList(options);
// This is ill advised
showOption.setLocation(300, 50);
showOption.setSize(140,100);
showOption.setVisibleRowCount(10);
// What about the last JList?
textPanel.add(showOption);
This raises a number of possibilities, the likely one is that you are covering over the previous list, which is being brought to the front when textPanel is validated and painted.
Swing follows (loosly) the MVC paradigm (and for more details)
So instead of re-creating the view each time, you should simply re-create the model, for example...
public JPanel results(StringBuilder message)
{
DefaultListModel model = new DefaultListModel();
model.addElement(message);
showOption.setModel(model);
If showOption isn't created initially before this method is called, you should consider putting in a if statement to detect when showOption is null and initialise it appropriately.
You should also avoid using setLocation and setSize. Swing has being designed to operate with the use of layout managers, these make it possible to define workflow and general layout that can be used across multiple platforms.
Take a look at How to use lists and Laying Out Components Within a Container

Java swing -- Jpanel not rerendering/repainting itself

Im using a JPanel with propertyChangeListener and want it to rerender itself based on whenever a particular variable model changes. My code for the same is as follows --
public class LabelMacroEditor extends JPanel implements PropertyChangeListener {
private static final long serialVersionUID = 1L;
private LabelMacroModel model;
public LabelMacroEditor(LabelMacroModel bean) {
this.model = bean;
model.addPropertyChangeListener(this);
setupComponents();
validate();
setVisible(true);
}
public void setupComponents()
{
Box allButtons = Box.createVerticalBox();
JScrollPane macroModelScroller = new JScrollPane(allButtons);
macroModelScroller.setPreferredSize(new Dimension(300, 200));
for(MacroModel macroModel : model.getMacroModelList())
{
LabelMacroEditorEditableEntity macroEditorEntity = new LabelMacroEditorEditableEntity(macroModel);
Box entityBox = Box.createHorizontalBox();
entityBox.add(macroEditorEntity.getUpButton());
entityBox.add(Box.createHorizontalStrut(15));
entityBox.add(macroEditorEntity.getMacroDetailsButton());
entityBox.add(Box.createHorizontalStrut(15));
entityBox.add(macroEditorEntity.getDownButton());
allButtons.add(entityBox);
}
add(macroModelScroller);
}
#Override
public void propertyChange(PropertyChangeEvent arg0) {
revalidate();
repaint();
}
}
When i use the debug mode in eclipse i can see that whenever there is a change to model it triggers off the call propertyChange and it also runs over revalidate and repaint but only the JPanel display remains the same. It does not seem to be rerendering itself.
Anything fundamental that I'm missing here ?
EDIT :
An example snippet of a property im changing is as follows --
labelMacroModel.addMacroModel(addedMacroModel);
where labelMacroModel is of the type LabelMacroModel and addedMacroModel is of the type Macro
Now the relevant part of LabelMacroModel class that fires off the property change is as follows --
private List<MacroModel> macroModelList;// this is the list of all MacroModels
public void addMacroModel(MacroModel macroModel) {
macroModelList.add(macroModel);
pcs.fireIndexedPropertyChange("LabelMacroModel", macroModelList.size(), null, macroModel);
}

Its not clear how you are changing the components in the panel. If panel is not updated then repaint/revalidate will have no effect. I think you should not need revalidate/repaint to be called explicitly if you are not modifying the way components are laid out. JButton.setText should for example change the label of the button without need of calling repaint.

To expand on the answer by AKJ above, I think you should be reconstructing your components on property change. So doing a remove all then readding is one way to do this. Once you get this working you could be more selective about pushing the model update into the GUI eg if a new entry has been added then just add a new component to reflect this. The remove all / readd is fine for a lot of cases though. HTH.

Removing an item from the JList using ListModel as model type

I have the JList which is using ListModel and not the DefaultListModel. I don't want to change the type now because I am using this in many places. I want to remove a selected item from the same list. How do i do this? I am using the following code but its not working for me.
made_list.removeSelectionInterval(
made_list.getSelectedIndex(), made_list.getSelectedIndex());
--EDIT--
I am using the following code when I create my list:
made_list = new javax.swing.JList();
made_list.setModel(new DefaultListModel());
And then in the JButton mouseclick event, I am using the following code to remove the selected item from the list when the button is pressed
private void removeActionPerformed(java.awt.event.ActionEvent evt) {
//made_list.removeSelectionInterval(made_list.getSelectedIndex(),
//made_list.getSelectedIndex());
System.out.println(made_list.getModel());
DefaultListModel model = (DefaultListModel)made_list.getModel();
model.remove(1);
}

removeSelectionInterval removes nothing from the model or the list except the selection interval. The list items remain unscathed. I'm afraid that you're either going to have to extend your ListModel and give it a removeItem(...) method as well as listeners and the ability to fire notifiers, etc... a la AbstractListModel -- quite a lot of work! If it were my money, though, I'd go the easy route and simply use a DefaultListModel for my model as it is a lot safer to do it this way, a lot easier, and will take a lot less time. I know you state that you don't want to use these, but I think you'll find it a lot easier than your potential alternatives.
An example of an SSCCE is something like this:
import java.awt.event.*;
import javax.swing.*;
public class Foo1 {
private String[] elements = {"Monday", "Tueday", "Wednesday"};
private javax.swing.JList made_list = new javax.swing.JList();
public Foo1() {
made_list.setModel(new DefaultListModel());
for (String element : elements) {
((DefaultListModel) made_list.getModel()).addElement(element);
}
JButton removeItemBtn = new JButton("Remove Item");
removeItemBtn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
removeActionPerformed(e);
}
});
JPanel panel = new JPanel();
panel.add(new JScrollPane(made_list));
panel.add(removeItemBtn);
JOptionPane.showMessageDialog(null, panel);
}
private void removeActionPerformed(ActionEvent e) {
System.out.println("made_list's model: " + made_list.getModel());
System.out.println("Model from a fresh JList: " + new JList().getModel());
DefaultListModel model = (DefaultListModel) made_list.getModel();
if (model.size() > 0) {
model.remove(0);
}
}
public static void main(String[] args) {
new Foo1();
}
}

You've been given a link to different sections of the Swing tutorial in the past to help solve problems. This was done for a reason. It helps solve your current problem. It gives you a reference for future problems.
All you need to do is look at the Table of Contents for the Swing tutorial and you will find a section on "How to Use Lists" which has a working example that adds/removes items from a list. Please read the tutorial first.
Or if you can't remember how to find the Swing tutorial then read the JList API where you will find a link to the same tutorial.

//First added item into the list
DefaultListModel dlm1=new DefaultListModel();
listLeft.setModel(dlm1);
dlm1.addElement("A");
dlm1.addElement("B");
dlm1.addElement("C");
// Removeing element from list
Object[] temp=listRight.getSelectedValues();
if(temp.length>0)
{
for(int i=0;i<temp.length;i++)
{
dlm1.removeElement(temp[i]);
}
}

What Java Swing event can be used to know when application has finished starting?

I'm looking for a place to hook some code to programmatically create, size and position a JPanel after the application has finished loading.
I'm just starting with Java. I'm using NetBeans 6.5.1 with jdk1.6.0_13. I've used the new project wizard to create a basic Java/Swing desktop application. This is a SingleFrameApplication that uses a FrameView with a central main JPanel where all the UI elements are placed.
I first tried my code in the FrameView constructor but when I try to arrange my JPanel based on the bounding rectangle of one of the design time controls I added to the UI, that control has not yet finished being positioned and sized so I'm getting all zeros for the coordinates.
I've verified my code works as expected by calling it from a click event after the application has loaded so my problem is finding a way to know when everything is finished being sized and arranged.
I also tried the componentShown event from the main JPanel but I later read that is only fired if setVisible is explicitly called which apparently doesn't happen during normal application startup.
Can anyone provide some pointers? Thanks.
Update:
In addition to what I mention in my answer below, I also read about the Application.ready() method. This would also be a point in time of interest for knowing when the UI part of an application is finished doing everything it needs to do. Communicating to my view from the application seemed a bit messy though.

The solution I went with was actually a combination of the answers from Charles Marin and JRL (I upvoted both of your answers for credit, thanks).
I had my FrameView class implement WindowListener.
...
public class MyView extends FrameView implements WindowListener
...
and in my FrameView constructor I added a listener to the application's main frame.
...
getFrame().addWindowListener((WindowListener) this);
...
Then in my implementation of windowActivated I could call the code I had to arrange and size a control on the main JPanel based on the location and size of other controls.
public void windowActivated(WindowEvent e)
{
// The application should now be finished doing its startup stuff.
// Position and size a control based on other UI controls here
}

I think you want WindowActivated. Have a look at this part of the tutorial.

I'd try using getFrame().isValid()

I assume this is the WYSIWYG editor thing. I'm looking at NetBeans 6.1, so your experiences may vary.
The traditional way to layout Swing components is by using a LayoutManager (or LayoutManager2). According to the NetBeans help, the visual editor supports these so long as they don't require support for constraints.
The procedure goes something like this:
Create a new JavaBean and have it implement LayoutManager (a BeanInfo is required too for palette support - you can create one by right-clicking the bean class)
Build the project
Right-click the bean and choose Tools > Add to Palette... and add it
Right-click the panel for which you want to set the layout and select Set Layout > Your Bean Name
You may find the design-time experience somewhat lacking.
A sample layout implementation:
public class StepLayoutBean extends Object implements Serializable, LayoutManager {
public void addLayoutComponent(String name, Component component) {
}
public void layoutContainer(Container container) {
Dimension space = container.getSize();
int xoffset = 0;
int yoffset = 0;
for (Component kid : container.getComponents()) {
Dimension prefSize = kid.getPreferredSize();
if (prefSize.width + xoffset > space.width) {
xoffset = 0;
}
Rectangle bounds = new Rectangle(xoffset, yoffset, prefSize.width, prefSize.height);
kid.setBounds(bounds);
xoffset += prefSize.width;
yoffset += prefSize.height;
}
}
public Dimension minimumLayoutSize(Container container) {
Dimension size = new Dimension();
for (Component kid : container.getComponents()) {
Dimension minSize = kid.getMinimumSize();
size.width = minSize.width > size.width ? minSize.width : size.width;
size.height += minSize.height;
}
return size;
}
public Dimension preferredLayoutSize(Container container) {
Dimension size = new Dimension();
for (Component kid : container.getComponents()) {
Dimension prefSize = kid.getPreferredSize();
size.width += prefSize.width;
size.height += prefSize.height;
}
return size;
}
public void removeLayoutComponent(Component component) {
}
}
If a custom layout doesn't fit the bill, have a look at the event bindings under the component's properties panel - though resizing that way might be a recipe for some kind of recursive event storm.