I'm quite confused and I when I try to find an answer with google I get bombarded with tutorials.
What is the purpose of each one?
How are they connected?
What is the purpose of the connection?
In java canvas is area used to draw something by java graphics. For ex. drawing an image or rectangle.
Frame is used as JFrame(swing), a top level container which can contain canvas, panels, pane(DesktopPane, ScrollPane) etc..
Panel or JPanel is a subcontainer used to contain textboxes, buttons, canvas etc.
Jframe can contain multiple panels, but panel can't contain JFrame.
Textboxes, buttons can directly be added to Jframe but it decreases flexibility, Suppose we want to hide a set of buttons from ui, then we need to hide them one by one from JFrame. If those text boxes are added to panel then we just need to hide that panel only. There are so many cases about using panel in jframe.
Related
I have two JPanel instances in a JLayeredPane, on different z-orders. I want both of my child JPanels to always fill the space of the LayeredPane.
The idea is for me to toggle the display of a 2nd panel over top of the first to display a modal-like dialog. Yes, I could just use a JDialog, but I thought it would be fun to try and create some transparancy overtop of the covered JPanel for a nice effect.
I find that using a layout manager on the JLayeredPane, like BorderLayout, and trying to set both children to CENTER conflicts since both panels can't be in the Center.
Is there a trick that I'm not seeing?
The idea is for me to toggle the display of a 2nd panel over top of the first
The easiest way to do this is to use a Glass Pane.
Check out the Disabled Glass Pane for an example of this approach.
There are two ways to create some "Glass Panel like" overlay for JPanels with JLayeredPane:
Add a ComponentListener to the JLayeredPane and update the sizes of all child components whenever the size of the JLayeredPane changes
Create a simple FillLayout, which expands the size of its child Components to the size of the Layout Container (In our case the JLayeredPane). You need to keep a list of children Components. During layoutContainer you copy the dimensions of the Container to these child Components. I wrote this and its really simple, but unfortunately I can't post it, since it's corporate. But if anyone is interested just ask in the comments. The implementation basically consists of one-liners.
For both solutions you need to make sure, that the panels on top are transparent, by setting setOpaque to false. This ensures that underlying panels render their content.
I noticed when adding multiple panels in JFrame content pane, if you set all the panels to be visible, you going to see (with set different background color ) some of them overlapping each other. I wanted to know if it is possible to have one master panel, that even though you add extra panels, that one panel from before will remain on top of all them?
I am working in the NetBeans. For that when I am working in the new JFrame form or the design view if I add the panel and then add the label and rest of the contents, it makes no difference if I don't add a panel and add the contents like JLabel, JButton, etc. it makes no difference.
Is there any reason why panel should be added to the frame? I tried to close the application when the panel was inserted and when it was not inserted on the frame, the application closes both the times. (When I press run and try to close the application, both times it closes.)
Then what is the use of putting JPanel on a JFrame?
When you add components to the frame the components are added to the content pane of the frame which by default is a JPanel. Read the section from the Swing tutorial on Using Top Level Containers for more information.
By creating a separate panel and adding components to that panel you give yourself more flexibility when designing your application. For example you may want to use a CardLayout which allows you to swap out different panels on the frame. The tutorial also has a section on using CardLayout.
What is the best way to display let's say rectangle (3x5) with icons 20x20 px.? I want to change the image file of every pic icon later (= it's not just static pictures). I tried to make JFrame full of JPanels, but i was able to display only one panel at a time. I don't want to use GridLayout, because I need just small rectangle inside a frame. Any ideas how to do it? Couldn't find any tutorial or solution. I'm completely new to GUI developement. Thanks
You do want to use a GridLayout. Your problem is that the JFrame you put the icons into uses a BorderLayout by default (and really, you shouldn't change the layout of a top level component).
What this means is that, if you add multiple panels to the frame, without using one of the NORTH, EAST, SOUTH, WEST constraints, only one of the panels will be visible and take up all the space. If you use a GridLayout for that one panel you get, the icons will be stretched, because the panel receives all the space due to the frame's BorderLayout. An alternate layout that doesn't stretch its contents is FlowLayout, but the layout to use depends heavily on your context.
To display the icons, a JLabel is handy. Use an ImageIcon for the label's icon. You can later use setIcon() on the label to choose a new icon.
overall, my approach would be this:
use a JFrame which has a BorderLayout
to the frame, add a JPanel to the frame. The default layout is a FlowLayout, which will prevent the stretching
to the panel, add a JPanel with an appropriate GridLayout
to that panel, add the JLabels, each having an appropriate ImageIcon
I want to display a JFrame ( made with the Netbeans GUI Editor ) that has an enclosed panel ( the panel encovers the entire JFrame ). The panel is twice as wide as the frame, so I want it so that when a button is pressed inside of the panel, the panel's visible area slides over ( over about 2 seconds) to the hidden area of the JPanel and the previously visible section of the JPanel becomes invisible. I couldn't find any function how to set the currently visible section of a JPanel, so the function and/or a different solution to this would be helpful.
I suggest that you put the JPanel in a JScrollPane, one that if you wish does not show its scrollbars. Then you could easily use the scrollpane's model and a Swing Timer to create an animation that shows the JPanel sliding.
The solutions is CardLayout based http://java-sl.com/tip_slider.html
You can add 2 (or more) panels into container and rotate them.