One of my classes is returning a JPanel which is added on a JFrame by some other class.
The JPanel contains a JTree and some buttons. On some events the panel is created again and returned to the JFrame.
My problem is that I have to add the JPanel to the Container of the JFrame again and then resize the frame for changes to be visible. I can't figure how to have the frame update without resizing.I tried removing old objects and adding updated ones but still doesn't work.
What is the best way to deal with this issue? Ideally I would have a reference to the JPanel and when the JPanel is changed, the frame will also be updated.
The whole model is changing not just its data. I will probably change this in the future but for now when data change a new JTree is created
Then your code should be something like:
JTree tree = new JTree( theNewModel );
scrollPane.setViewportView( tree );
That is you need to add the new JTree to the GUI, you can't just change the reference to the tree variable.
Or even easier, you don't need to create a new JTree, just replace the model in the existing tree using:
tree.setModel( theNewModel );
If this still doesn't help then you need to post your SSCCE that demonstrates the problem because your question still isn't clear.
try JFrame.invalidate() first, then call JFrame.validate()
http://docs.oracle.com/javase/6/docs/api/java/awt/Container.html#invalidate%28%29
Related
I am trying to implement a basic GUI where a user can move objects from one JList to another. The JLists should be contained within a ScrollPane so size is not an issue. Basic functionality is good, items will move and remove with button presses. However, the JList and JScrollPane that items are added to will display correctly and detect if a ScrollBar is necessary but do not interact AT ALL with the user for some reason. The user cannot select from the JList nor scroll the ScrollPane. Rough idea of the code below;
public void createJList(Type[] dataToList){
someScrollPane = new JScrollPane(); //someScrollPane is private global
someScrollPane.setBounds(numbers here);
this.add(someScrollPane); //this is a custom frame class
aList = new JList<Type>(dataToList);
someScrollPane.setViewportView(aList);
This is a rough idea. I also add a listener at some stage but since the scrollpane isn't working either I may as well leave that for later. I use this code for both the working and non-responsive JLists and ScrollPanes exactly the same.
Of note, I call this method everytime the list I want to display is changed. I'm thinking maybe because the JList and ScrollPane keep getting created, something is broken?
I so my problem is this:
I made a JPanel. Inside it I want to add a JList with a scroll-bar. So I use JScrollPane.
Here you can see a picture of the application. The big white recangle is the size of the JPanel. In the second picture you see what happens when I add the Scrollpane to the code.
Here is the code I use:
public class GUI extends JFrame{
DefaultListModel m = new DefaultListModel();
JList myList = new JList(m);
JScrollPane scrollPane = new JScrollPane(myList);
JPanel listPanel = new JPanel();
public GUI(){
//Stuff about Frame Size, title, and other boring things
scrollPane.setViewportView(myList);
listPanel.add(scrollPane);
this.add(listPanel);
}
}
I have used it before, and it worked. Well, I faced the same problem, but it went away. I have written this code the same way as I did the previous time. But this time it doesn't work.
thanks in advance guys.
With JList you can simply use setVisibleRowCount to adjust the size of the viewable area of the JScrollPane
The other problem is JPanel uses a FlowLayout by default, you may want to change the use something like BorderLayout instead
Updated
As pointed out, if the list contains a large number of elements, you can use setPrototypeValue to improve the efficiency
Okay, so apparently I have to setPreferredSize. You can't just set the size of the panel, you need to set the size of the jscrolpane too!
By default, unless you use something like a grid bag layout...
Also, for developing UI's in Java, it is extremely helpful to install an eclipse plugin called WindowBuilder
I have a frame with a var , I added that var to a JPanel, and if I want to add the same var to another JPanel, it`s disappearing from the first JPanel. I want a logical explanation for my problem please, thank you !
I want to store my JLabel in both of my jpanels.
public class Gui {
JPanel panel1, panel2;
JLabel text = new JLabel("some text");
JFrame frame = new JFrame();
public Gui {
panel1 = new JPanel();
panel1.setLayout(null);
panel1.add(text);
panel1.getComponent(0).setBounds(50,50,50,50);
panel1.setBorder(BorderFactory.createLineBorder(Color.black));
panel1.setBounds(x,y,w,h);
// it`s working, the labels it`s visible
panel2 = new JPanel();
panel2.setLayout(null);
panel2.add(text);
panel2.getComponent(0).setBounds(100,100,50,50);
panel2.setBorder(BorderFactory.createLineBorder(Color.black));
panel2.setBounds(x,y,w,h);
//it`s not working, the label ins`t visible ...
frame.add(panel1);
frame.add(panel2);
}
}
Disclaimer: I am editing my answer in response to comments from the OP. However, I am still not entirely sure about some of the details of the question. I will gladly edit my answer as more clarifications are given.
Answer: One possible solution is to create subclasses of the Swing components you are using. For example,
public class MyPanel extends JPanel {
private JLabel label = new JLabel("some text");
public MyPanel() {
this.add(label);
}
}
Now you can create multiple instances of MyPanel which each have its own JLabel. Then you can add these panels to your frame.
Added: With the additional information given in the comments, I would go a step further and create a custom JFrame class:
public class MyFrame extends JFrame {
private MyPanel panel = new MyPanel();
public MyFrame() {
this.add(panel);
}
}
Now you can create several instances of MyFrame. If you want to go even further, you can add parameters to the constructors of both of these custom classes to set the JLabel text to different values in each instance MyFrame. I will leave the details as an exercise to the reader. (Of course, please ask if you get stuck, though.)
Just as it's discussed with in other posts. All Swing UI components (ie JLabel included) can only have one parent (ie JPanel). If you add it to another panel it will remove itself from the prior parent. There are very good reasons for this behavior. For example, JPanel 1 might not use the same Layout as JPanel 2 and hence the label would have to support two different placements within each JPanel. The whole point of using Objects as components is to provide encapsulation of data like (font, position within the parent, width, height, etc) inside that object. If you want two visual elements just create another element. Now that creates a problem "How do you synchronize the data across all of these controls?" That's basically scratching how do you build a proper Swing architecture for your program?
What you don't want to do is use the Swing component model (ie. Jabel, JTextField, etc) as your data model. And after reading your question and code I believe that's what you are doing. You may not realize it. UI Components should be used for display only. They reflect what is in the data model. So you'll want to create a model that doesn't involve Swing. It should model your problem regardless of how its displayed. That means you shouldn't assume it will always be Swing or web, etc.
There are very practical reasons for this. Say in a year you want to redesign your UI. If you combined the view components and data model together you pretty much have to start completely over. Even if you aren't switching technologies. Say you are switching from a JList to a JTable or a JTreeTable. Just simple changes of the types of components you have on the screen can be an absolute nightmare if you don't segment your view from the model. Plus the View displays thing, but the model might need information that isn't displayed to the user but is tied to what is being displayed. For example, the ID of the row in the database. If you stuff the view and data model together you have to play little hacks to store this invisible information in weird ways. Things that make it hard for other people to understand.
If you don't know what I mean you either will in 6 months when you have to make your first major redesign or you'll save yourself some pain now and try and understand what I mean now. Just simple POJOs will suffice. Then share those POJOs with your Swing components. For example:
MySpecialPanel panel1 = new MySpecialPanel();
MyOtherSPecialPanel panel2 = new MyOtherSpecialPanel();
frame.add( panel1 );
frame.add( panel2 );
...a little while later...
MySpecialPOJO specialPOJO = ...some call to a service...;
panel1.setSpecialPOJO( specialPOJO );
panel2.setSpecialPOJO( specialPOJO );
Notice that I created two subclasses of JPanel called MySpecialPanel and MyOtherSpecialPanel. Inside there they create the components contained within them. Then then expose a setter method taking a data model object of type MySpecialPOJO. Inside those methods we might see something like the following:
public void setSpecialPOJO( MySpecialPOJO specialPOJO ) {
this.model = specialPOJO;
textField1.setText( specialPOJO.getName() );
textField2.setText( specialPOJO.getDescription() );
radioButtonGroup.setSelected( specialPOJO.getGender() );
....
}
Now you have a way to take a model object, and update the relative UI components that make up that view. Notice it doesn't care about any other external dependencies (ie where it got the object from). It just updates the controls it owns to reflect what's carried by the POJO. Now if you follow these simple rules it makes instantiating your special panels easy. Whether you need only one instance or many instances. Also if you need to move panels within your program it's pretty easy to do that if you reduce your dependencies to just your POJOs. There's a lot more to this, but for now this will get you started. You still have to figure out how to get data out of the UI and back into your POJOs (events!). Controllers, Services, etc.
This might help you as well:
Up-to-date Swing MVC example + Question
You can't. As you noticed, a control can only be attached to one window at a time, and if you try to attach it to another one, it will remove itself from the first.
Suggestions:
panel2.add(text.clone()); // clone the existing label
panel2.add(new JLabel("some text")); // make a new label from scratch
I have a JFrame inside of which is a jpanel that im using as the content pane.
So basically im using the jpanel to load content into on click. New content is returned as a Jpanel also so its ends up being jpanel -> inside jpanel -> inside Jframe. When i need to load in new content i clear the panel, load the new content and validate() the jframe & jpanel and the new content displays.
My problem is that when the new content displays its clear that the validate method is working because i can see the new interface but i can also see the old interface as if its become the background; i can resize the window and it just disappears and looks as it should.
Is this just the way validate works or can i fix it?
Edit: this worked. The problem was i wasn't calling repaint manually.
public BaseWindow setContent(JComponent comp){
contentPane.add(comp);
contentPane.revalidate();
contentPane.repaint();
return this;
}
Generally the code for adding/removing one or two components from a panel is:
panel.remove(..);
panel.add(...);
panel.revalidate();
panel.repaint(); // sometimes needed
However, if you are replacing all the components on the panel, then the better approach is to use a Card Layout.
You have already stated the revaliate() followed by repaint() doesn't work so the only suggestion I have is to post your SSCCE that demonstrates the problem.
Don't use validate. Use revalidate() instead.
Revalidate first calls invalidate() followed by a validate().
In Swing, you would rarely use validate().
Note: I also feel that maybe the old panel is not cleared/removed.Check again!
Validate() is for causing components to re arrange themselves according to the layoutmanager that you have installed. This is not really what you should be using.
I can't see your code, so I'm not sure exactly what you are doing. I could speculate that calling repaint() on your "inner panel" will solve the problem you are having...but really, if you are doing things properly, you shouldn't need to call repaint() or validate().
Make two JPanels, one with content A (e.g. your buttons), and one with content B (e.g. your "static" field). Use the "add()" and "remove()" methods on the parent container (the JFrame's content pane?) to swap these two JPanels with each other whenever you want to switch the content that is displayed in that part of the JFrame.
Then you shouldn't need to do anything else; it should just work.
I don't know if validate() makes any promise about fully repainting the container. You might have to call repaint() yourself to make it behave as you want to.
Here's another possible solution:
Put both JPanels in at the same time, side by side, and then make sure only one of them is ever visible at any one time:
JPanel p = new JPanel(new BorderLayout());
p.add( panelA, BorderLayout.EAST );
p.add( panelB, BroderLayout.WEST );
panelA.setVisible(true);
panelB.setVisible(false);
Then when the user clicks the button to switch panels:
panelA.setVisible(false);
panelB.setVisible(true);
The setVisible() method and BorderLayout should take care of validating, layout, and calls to repaint() for you.
I ended up fixing my issue (display not shown, buttons would stay clicked/weren't unclicking) by changing which panels were added/removed.
Problem:
frame.removeAll();
frame.add(getNewPanelDisplay());
frame.revalidate();
frame.repaint();
Solution:
//initializer()
mainPanel = new JPanel();
frame.add(mainPanel());
// ...
//update()
mainPanel.remove(0);
mainPanel.add(getTablePanel(), 0);
frame.revalidate();
frame.repaint();
I have Java application which adds JTextFields # runtime to JPanel. Basically user clicks a button and new JTextField is added, clicks again added again...
Each new JTextField is directly below the previous one. Obviously I run out of space pretty soon so I'm trying to use JScrollPane and thats where the hell begins, because it just doesnt work no matter what I try.
Right click on JPanel and Enclose in Scroll Pane. Didnt work.
After reading some examples I realized I must have JPanel as an argument for JScrollPane constructor. Which I did via right clicking on ScrollPane and CustomizeCode. Because apparently auto-generated code is protected in NetBeans and I cannot just change all those declarations, etc. manually. Still doesnt work.
I did try to set PreferedSize to null for JPanel and/or JScrollPane, didnt help.
JScrollPane is a child of lets call it TabJPanel (which in turn is a tab of TabbedPane). I tried to mess with their relationships, basically trying every possible way of parentship between JFrame, JPanel(holding textfields), TabJPanel and JScrollPane, but nothing worked.
I also made VerticalScrollBar "always visible" just in a case. So I see the scrollbar, it's just that populating that JPanel with JTextFields does not affect it.
When there are too many JTextFields I they go "below" the bottom border of JPanel and I cannot see them anymore.
Code for adding new JTextFields is like this, in a case it's relevant.
JTextField newField = new JTextField( columns );
Rectangle coordinates = previousTextField.getBounds();
newField.setBounds(coordinates.x , coordinates.y + 50, coordinates.width, coordinates.height);
JPanel.add(newField);
JPanel.revalidate();
JPanel.repaint();
Sorry for a long post I'm just trying to provide as much info as possible, because being newbie I dont know whats exactly relevant and whats not. Thanks in advance :)
As there is another answer now, I'm adding my suggestion too.
This sounds exactly like a problem to use a JTable with a single column. JList is not yet editable (and might never be).
JTable would handle the layout problems for you, and you can easily access the values via the table.
Use your own TableModel (a simple Vector should be sufficient in your case), and add values to it.
An option you have is to utilize a LayoutManager, instead of setting the bounds directly on the components. To test this, a simple single column GridLayout with the alignment set to vertical should prove the concept.
panel.setLayout(new GridLayout(0,1));
zero in the rows param allows for rows to be added to the layout as needed.
I do this way to add a scrollpane, create a panel and fill it with few components, then create a scrollpane in the component you want to add it, cut and paste the panel in which all your details will fall in and resize the scrollpane.Because the components take a larger space than the one visible right click on the scrollpane and select design this container, there you can increase the size of the scrollpane and add as many components as you have.