I am using NetBeans 7.2. I have a JFrame with Card Layout having one Main Panel and Several Sub Panels. As you can guess all auto generated Swing component definitions are declared in single file, and its all messed up.
How can I separate these panels say in a package, to make it more modular? Or am I taking completely wrong approach ?
You can create JPanel forms with the builder tool. New -> Swing Forms -> JPanel Form. Then to see them in the design view, just drag and drop them onto the card layout panel as seen here
slightly wrong approach.. if you want to make the panels something like modular, just create a new panel class inside the package, not many panels on the same class.. create new panel class and pass it to ur main panel..
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I am now writing code simple GUI that's for start the game window. I only need Do you want to start game message and start button on the window. But I have a confusing concepts for the JFrame and JPanel. Actually, I thought I need to add JPanel to JFrame to add the other components such as JLabel, JButton,...etc. But I realized I don't actually need JPanel. I can just add the components simply use add(button), add(label) to JFrame. So why I need JPanel. And I think JFrame doesn't need JPanel but JPanel need JFrame. Am I understand correctly?
No, not always. A simple graphical user interface may be implemented by just adding components "directly" to a JFrame. But in order to get more flexibility, you would always use JPanels. For example, to employ different layouts in different parts of the GUI, to group certain components together, etc.
A JFrame is backed by a JRootPane, a part of which is a contentPane.
(image from Oracle Javadoc)
When you add components to a JFrame, you are really adding them to the content pane, e.g.: frame.getContentPane().add(Component).
A JFrame is a common starting scene of a Swing GUI application, while a JPanel is intended to be put in another scene (container). Since both content pane and a JPanel inherit from the same class (Container) you may use them in a similar manner, as far as adding components to them goes.
Do I need JPanel always?
No. Well, unless you need a Swing GUI. Then yes.
Another answer replied words to the effect. "No, you can add components direct to a frame" What they missed was that components added to a JFrame are added to the content pane (automatically). The content pane is a JPanel.
Having said that:
I (and many others) would recommend designing an app based around a main content panel, then adding that panel to a top-level container as needed. The top level container might be a JFrame, JWindow, JDialog, JOptionPane ..
What prompted the question? A JPanel is a very 'light weight' container (in more ways than one). A GUI can contain 1000s and not be burdened by doing so. Of course, that's a rare requirement, but just saying .. use panels as needed and don't worry about it.
I have a very big Frame made with Netbeans GUI Builder. And of course, made by default all inside one file, called JFrameTest.java.
Now I want to modularise my code. I have a JFrame containing a JTabbedPane and inside a lot of JPanel.
What I want is to have for each JPanel inside the JTabbedPane a specific java file, with inside actions, subviews, etc ...
It is too late now ?
I means, all my Panel have subviews like JTable, Button, etc .. and are inside the JFrameTest file.
There is not a way to say : Move the Panel and its subviews inside this CustomJPanel class, etc.. ?
I originally made a complex GUI in JFrame Form by the form editor.
There are several Jpanels inside the frame.
Now I am thinking of reusing some of the JPanels in other JFrames.
I know it is possible to copy and paste the JPanel, but what I really want to do is factoring out the JPanel to make it a class. Is it possible to do it in Netbeans?
EDIT:
Thanks for the advices, it was really helpful, but not solving my problem.
I still need to factor out the panel. Say if I have a Panel with several child panels inside. (eg: tabbed panel) I would like to design each of the child panel separately instead of doing them all together in a single class. That's my understanding of OOP. I did not do it at the first place because I was not familiar with netbeans nor I was an good designer. Now I realize I need to reuse some of the child panels. Am I able to factor out the code for each panel and make it a class without redoing the work? I used GridbagLayout.
I'm quite new to Swing, and I'm programming an application with NetBeans' UI designer.
Now I have an JPanel called "editorPanel", and it must be able to display multiple things. (so, sometimes it has to display an image, and sometimes it has to display a text editor)
I have made separate panels for this, so say I'd have a JPanel called ImagePanel and one called TextPanel. It has to switch easily between them, so I tried this:
editorPanel = new ImagePanel();
But that didn't work.
So, what I want to do, is set an empty panel to a defined panel.
How can I make this work?
The proper way to achieve your goal is to using a card layout and switching panels accordingly.
You ca get some idea on how card layout stuff is working in here
I read that JFrame is made of several panes ..what are panes and why is Jframe made of panes ?
And why there is a JPanel while it seems that the JFrame looks exactly like the JPanel but with a menu bar and a close button so what's the need for a JPanel ? Can anybody explain to me clearly the definition and use of those 3 components ?
There are top level containers such as JFrame. These can serve as the main window in which a GUI is built.
Then there are intermediate level containers. These must be placed in other containers, they cannot exist by themselves. They either help you organize components or they add functionality. A JPanel is a very simple container that helps you to organize other components. While a JSplitPane adds the functionality of having two panes that are variable sized.
When you have a complex GUI you may want to use JPanels to organize various areas of your GUI and then add each of the panels to your JFrame.
In Java the Swing API makes use of the Composite Design Pattern. This means that you can compose very complex objects from other objects and still treat the composite objects the same way as the simple objects. So you can put a JPanel into a JPanel and it still behaves like a JPanel.
Think of it like a tackle box (or sewing kit). It is made of a big container. But rather than put many small objects into this big container and make it difficult to manage later you can place some smaller compartments inside the big box. Then hooks and sinkers etc go in the compartments. Its easier to manage. The big box is the JFrame and the compartments are the JPanels.