I'm using Netbeans making an application in Swing. I've created a expandable/foldable drawer to be used in various situations that is meant to contain other GUI components.
This is similar to that of things like JPanel, JScrollPane, JTabbedPane, etc.
However, when I drag my component in to the designer, I cannot add any components under it. Is there a way to make my drawer a container?
Additional Info:
I have selected an example jPanel for instance, note how it has the '+' option. You can add child components under it. My own components, SideDrawer and ScrollableLoadableStripedTables have no such option. I'd like to be able to add it. I'd like to make my component, which extends JPanel act more like a container
Related
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 created a JFrame - now I want to add the 4 JPanel in that frame at a particular location. How can set the location of panels in the frame?
Use (possibly nested1) layouts for the logic. See Laying Out Components Within a Container for details. They can:
Include default spacing in the constructor (often)
Calculate how big the GUI needs to be in order to display the components (in whatever PLAF, on whatever system the app. is deployed).
Extra spacing can be organized by adding an EmtpyBorder to child components.
See the nested layout example
Placing components in a container is quite a complicated subject in Swing. Instead of defining the exact places for your components, you would normally use a layout manager that arranges them in a certain way.
Here is the tutorial you should read to get a (visual) clue about the different layout managers: A Visual Guide to Layout Managers
However, the standard layout managers of Swing can be cumbersome for more complex layouts. Either, you could use nested layouts to get the desired result, or you could use a very powerful third-party library: JGoodies Forms. The downside is of course that you have to learn yet another library. Therefore, I would only recommend it for a bigger project.
For me it is good way to set GridbagLayout for the container of the frame. There are several visual swing GUI editors available to do this easily. You can use NetBeans GUI editor or GWT Designer (https://developers.google.com/web-toolkit/tools/gwtdesigner/) for complex GUI designing tasks
If its 4 locations, you can use BorderLayout,by default its the CENTRE, but it also have EAST, WEST , NORTH, SOUTH locations for the placement of the components. You can also use setLocation to put the panels in the appropriate locations, if a layout isn't used.
Its even better to use GroupLayout developed my NetBeans team in 2005, use Windows Builder Pro, now provided by google for free.
set the layout of the Frame to be null via setLayout(null)
create 4 JPanel and set their location using setLocation method
add these panels using JFrame's add method
I want to draw a line between different components in a JPanel, but the line should be a component, ie, it can be clicked, highlighted, selected and deleted instead of just painting a line in a panel, is there anything like this or I must implement it by myself. And if I must implement it, how?
You could use a JSeparator. But you'll have to implement the click, highlighting, selection and deletion yourself. A JSeparator is just use to... separate sections in a panel.
If you mean that all these operations should be available when designing your GUI in a wysiwyg editor like NetBeans Matisse, then JSeparator is just what you need.
I tried to use prepared things like JSeparator, But I found the best way by myself and I implement it. I used a JLayeredPane for my container. I add my own JPanel behind the all layers and override its paint() method. in paint() method I used Java2D to draw a curve between Components on higher layers in JLayeredPane. You can see the result in below.
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.
I am currently trying to build an expanding panel in Swing (akin the WPF's Expander control) and I'd like to retain the usual methods for manipulating it (i. e. setLayout, add, etc.). Only they should be routed to an embedded panel (the one being shown or hidden).
How would one do that? Overriding every method of JComponent and re-routing that to an embedded JPanel would be cumbersome, but that's the only way I see.
Or should I rather make the embedded panel visible to the outside and force users to use something like ExpanderPanel.getInnerPanel() instead. But then it's no drop-in replacement for JPanel which I think would be nice to have.
Take a look at the JXTaskPane from Swingx project. It already does what you need.
In 1.5(ish) Swing routed a few methods to the content pane in JFrame, JApplet, etc. Whilst there appeared to be some usability benefits for those just starting, it doesn't actually fix the problem. So everyone has to deal with a very strangely behaving API. So my advice is to avoid this approach.
If you have a Container widget which holds a panel you want to show and hide, why not layout your inner panel however you want, then add it to the Container panel, then use static methods against the Container to say
JPanel p = new JPanel();
//do something with the JPanel...
ContainerWidget.setContent(p);
ContainerWidget.expandPanel(p,true);
Would somethign like this work?