Develop Reference

JTable only showing after I resize the JPanel in Eclipse

I have a button called btnDisplay on a JPanel called TempPanel. When the button is clicked, it should display a JTable that is created manually.
However the table is only visible to me after I resize the panel manually with a mouse. Even if I make the panel smaller than it originally was, it shows the table, otherwise it doesn't.
What is the reason for this? And how can I fix it?

I'm writing the comment as an answer for clarity purpose:
Call revalidate and repaint on the container to which the JTable is been added

How do I get a JPopupMenu to "shadow" a component consistently

I have a custom auto complete JTextField. I use the JPopupMenu to contain the selection.
I want to pop the JPopupMenu right under the JTextField using this method.
Rectangle r = textField.getBounds();
popup.show(textField, (int)(r.getX()), (int)(r.getY() + textField.getHeight));
popup.setVisible(true);
It works when I put the component in a simple JFrame. But when I put the component in a complex layout with JScrollPane. The location becomes random and inconsistent. I'd like the popupMenu to "shadow" the textField in any condition. How do I achieve that? Thanks.

The popup location is relative to the parent component.
popup.show(textField, 0, textField.getHeight());
should place it right under the textField.

add panel to combobox popup menu

i have jFrame = frame
it have jcombobox = combo
then i have jpanel = panel
i have many component inside this panel
i try to add this panel into combobox popupmenu
so if combobox clicked,
panel that have many components will show up
it is possible to add panel into combobox popup menu?!?!
how to do it???
i already read
http://docs.oracle.com/javase/tutorial/uiswing/components/combobox.html
and
http://docs.oracle.com/javase/tutorial/uiswing/examples/components/ComboBoxDemoProject/src/components/ComboBoxDemo.java
but still not have any clue
how to do it?
thankz a lot for any help...

So from your description, you have a panel that is not visible, that you would like to appear if the combobox is clicked? So it will appear for any option in the combobox?
That should be simple enough. Lets modify the JLabel in this ComboBoxDemo from the Java Tutorials. Since they both inherit from JComponent, we will be able to make the JLabel and the JPanel visible in the same way.
First, make sure you understand what the demo is doing. The Combobox options are changing the format of the date's text in the JLabel. We want to edit the demo in such a way that this JLabel is not visible until after we select any option in our JComboBox.
First, we will want to include a boolean as a class variable, so that we can access it in any of our methods.
boolean visibleComp;
Next, in the constructor, you will want to change the JLabel "result" to be invisible by default. We can do this by using the setVisible method of the JComponent.
result.setVisible(false);
Now we need to control when and how result becomes visible -- as we continue through the code, we see that the actionPerformed method handles our events, and passes the formatting details off to another method called reformat.
Since reformat is also called in our constructor, we will want to set our boolean value in the actionPerformed method.
visibleComp = true;
We will then want to add a conditional statement to the try block in reformat -- this will check to see if our boolean is true, which would only occur if an action had been performed by the user. We can use this to set our component's visibility.
if(visibleComp){
result.setVisible(true);
}
You can easily interchange a JPanel with this example. Hope that helps.

Manage multiple Jlabel's events

I have a left Panel with multiples Jlabels which i use them as buttons to change a Main Panel's content which is layouted with a CardLayout.
I cant work perfectly with these events:
mouseEntered : to make highlight effect to the jlabel
mouseExited : to take off the highlight effect.
mouseClicked : to change the content of the main Panel and start some threads
The problem here that can't found an event or a method tell me that another Jlabel has been clicked so i can stop my threads started in the mouseClicked event,
OR
an event or method tell me that a JPanel in the CardLayout has been displayed or hidden.

Your problem is not finding an appropriate event. I think you are doing this using a visual GUI builder and expect to solve everything out-of-the-box. It's not going to work that way, you will need to write some real code. For example, write a method that you will call from the mouse click listener of each of the three JLabels. Thus you will have arranged for this method to be called for each JLabel click. Then in the method do the appropriate handling. This is just a rough outline, you haven't provided much detail to give any further advice.

It sounds like you need FocusEvents and FocusListeners. These are supported by all JComponents like JPanel, JLabel, and JButton, such as by calling addFocusListener();
Basically a FocusListener can tell you when a JComponent gains focus (such as by clicking on the JComponent) and when it looses focus (such as by clicking on a different JComponent).
Refer to http://docs.oracle.com/javase/1.4.2/docs/api/java/awt/event/FocusListener.html for further information

addMouseListener() won't work with JPanel under JScrollPane

I add my customized panel onto JScrollPane. I also have another set of "tool" that will attach itself to my custom panel. The problem is, in these tool, it invokes attached.addMouseListener(this). Normally, everything would function well, but when I have it inside JScrollPane, it won't function at all. My deduction is JScrollPane never gives window focus to its child component. Is there a way to get this around without having to change my attachment procedure? I want my 'tool' to specifically attach to my custom panel, not the scrollpane.

I hope I have understood the problem.
What about adding a MouseListener to the JScrollPane and then dispatch the event to the JPanel?
Somenthing like this:
//JScrollPane Listener
public void mousePressed(MouseEvent me) {
jpanel.dispatchEvent(me);
}
It's a little bit tricky, but so you don't have to change the JPanel Listener.