I am pretty new at . Java Swing, and am using the CardLayout for my application. In this app a user can create activities and, in an other JPanel, view the existing ones.
I am having trouble updating the card (where the label is in). If I add the activity, when you restart the app it works fine. I am looking for a way that doesn't require restarting.
So in short, I would like to know how I should best reconstruct/update a panel whilst running so that the new label data is shown.
Thanks in advance!
When you add a component to a visible GUI you need to tell the GUI that a component has been added so the layout manager can be invoked:
panel.add( component );
panel.revalidate();
It sounds like what you are looking for is the Observer design pattern.
Basicly what it's all about is you have one Observer instance, which you add all your panels to. When you update a value in a panel, you nofity the Observer something's changed. The Observer will then inform all his observed panels that a value has changed, and they'll update their value.
http://en.wikipedia.org/wiki/Observer_pattern
Related
I'm starting using java with NetBeans IDE. I'm using drag and dop GUI, it's so easy to use, but I got a problem. I'm writing this code at the contructor:
JComboBox combobox=new JComboBox();
combobox.addItem("Apple");
combobox.addItem("Banana");
for(int i=1;i<=10;i++){
combobox.addItem(i);
}
just right above initComponents(); hoping that my new combobox will shown when I run the project, but it doesn't. Did I do something wrong? Thanks in advance
Yes, you are creating a JComboBox, and yes, you are adding items to it (numeric and int -- that's a problem, but that's a discussion for another day), but no, you're not showing any code where you add this newly created JComboBox to a component that is displayed in the GUI. To display a component in a Swing GUI, it must be created and added to a component that is ultimately displayed in a top-level window, in the "GUI".
So this begs the question, how do you add your created JComboBox to your GUI that you've created with drag and drop code? One way: you could add it to say a JPanel that's already in your GUI, but you will need to do this after initializing components, usually this means after the constructor calls initComponents(), and you'll also need to make sure that this JPanel uses a layout manager that makes it easy for it to accept new components (this means most of the layout managers except NetBean's default layout, GroupLayout).
There are other issues, such as whether or not the container holding your JComboBox is large enough to display it, but the best suggestion that I can give is for you to go through the Swing tutorials, and hit especially hard the layout manager section. You can find links to the Swing tutorials and other Swing resources here: Swing Info.
I am making project with GUI. The thing is, that I have a button and what I need to do is that after clicking this button I need to change Frame layout. For example, like when you are installing some program and you click "next" button, the Frame layout changes and you can see some different content. Basicly, dynamic wizard.
I have tried use another Frame, but it opens in another window and that is not what I want. I want to open it in the same window.
Another thing I have tried is set visibility of these components I don't want to be displayed to false, but I find it unprofessional and it is overlook in making a desing, when I have components over themselfs.
So do you guys have any idea? Thank you.
Most of the times for a wizard like GUI, you should have JFrame and a set of JPanels. In each step you can pass the shared data as constructor arguments to each panel, and when you are making one of them invisible and make another one visible, you can get some date from the previous step panel and pass it to the next step panel(if needed).
It is very common that your panels extend the JPanel and have some argument in their constructor(s). You use these data for initializing your panel and managing the state of the overall progress.
There is no a total plan for all situations. So you should decide what to do which is best fit for your case.
Try not to have multiple JFrames.
Hope this would be helpful.
To expand upon the headline :
I have a screen (my main window, an encapsulated JFrame) that's going to be created most likely with a GridBagLayout, because I need a grid whose cells are to be differently-sized rectangles. In one of these rectangles will be a malleable dialog-like functionality, with different options depending on the context of the application.
My question is, are custom JDialogs the way to go here? Or do I simply want a reusable JPanel that has the particular buttons I want displayed or disabled depending on the context? I hope this is clear; thanks. -B.
Go with the JPanel solution.
JDialog is a heavy-weight, top-level container, meaning it's window is managed by the system and cannot be embedded as a child of another component.
In my Netbeans code I have JPanels and JDialog which are driving me crazy at times. Some of the controllers on these containers decide not to show up or automatically change size even though I have set up both their size and contents within the code and through using the IDE properties. For instance some of my jButtons on a certain JPanel does not show its text label or the sizes of some of my text field change.
Any solution to this would be grately appreciated!
When you create GUI using the NetBeans IDE wizards the Layout manager attached with JPanel and JFrame is GroupLayout and it works as expected. It keep the size of your JPanel and JFrame as you have specified.
Now if you change the LayoutManager of the JPanel or JFrame then you are on your own. You must know the consequences of changing the LayoutManager and update / add the required code to make the code to run as expected.
I will suggest you to keep the default LayoutManager as GroupLayout if you want to get what you see in the NetBeans component designer.
Unfortunately you did not provide any code snippet that can show your problem. But let me assume that you are confused with layout behavior. Typically we use Layout manager and delegate to it the responsibility of placing and re-sizing the graphical elements. Layout manager does it work when the parent element is being painted, i.e. during execution of method paint() that happens asynchronously and may be caused by various events (e.g. changing focus, re-sizing of window etc).
In this case all your attempts to change size of specific element by calling its setSize() could be overridden by layout manager that decides to change size of the same element differently.
So, if my assumption is correct learn to use layout managers and ask more specific questions if you have any difficulties with them.
I have developed my Java code in Netbeans, and now I want to develop the GUI for my application.
The application communicates with a server, so it's going to have a login frame for sure. After that there will be a main frame. From the main frame the user can choose where to go and as you can understand there will be a lot of frames.
I have already developed a version of the application where there are a lot of frames and using the "setVisible()", but I want something better looking. I want a stable frame and inside it, changing the panels or something similar.
How would I do this?
You might use JInternalFrames if you like them, or simply use a main panel with a CardLayout, and display the appropriate card depending on the clicked menu item, or the selected JTree node (as it's done in Windows Explorer and similar applications).
Use the Swing tutorial to get you started.
You can, at any time, make any Container object a JFrame's ContentPane. You can also add and remove Containers from any other Container. If you want a user to be able to jump to any of a dozen panels at any time, CardLayout, as suggested in another answer, is easily the best route. If, however, you intend to lead the user along a somewhat controlled path, you can start with a login JPanel. When that's done, you can create the next panel (a JPanel or something else), add it, and dispose of the first one. And so on until the user exits.
If the transition from one panel to another affects nothing else in the program besides the two panels and the parent Container (JFrame or descendant), this is probably the way to go. If a bunch of other places in the program need to know about the change, you'll want a more centralized mechanism, maybe using CardLayout.