I am trying to make a game, so I decided to create multiple JPanels, which all do something different, so only one JPanel is needed to render everything. To change them, I just do:
this.getContentPane().removeAll();
CURRENT_CONTENT = new JPanel();
this.getContentPane().add(CURRENT_CONTENT);
this.pack();
However, when I do this, although the JPanel is appropriately set, it also changes the size of the JFrame by slightly increasing it... How can I stop this from happening?
Thanks!
Thanks to the answers, I got it working!
pack() seemed to be the problem.
Here is the final result, in case someone has the same problem:
this.getContentPane().removeAll();
CURRENT_CONTENT = new JPanel();
this.getContentPane().add(CURRENT_CONTENT);
this.revalidate();
Thanks again!
Related
To put it simple, there's a simple java swing app that consists of JFrame with some components in it. One of the components is a JPanel that is meant to be replaced by another JPanel on user action.
So, what's the correct way of doing such a thing? I've tried
panel = new CustomJPanelWithComponentsOnIt();
parentFrameJPanelBelongsTo.pack();
but this won't work. What would you suggest?
Your use case, seems perfect for CardLayout.
In card layout you can add multiple panels in the same place, but then show or hide, one panel at a time.
1) Setting the first Panel:
JFrame frame=new JFrame();
frame.getContentPane().add(new JPanel());
2)Replacing the panel:
frame.getContentPane().removeAll();
frame.getContentPane().add(new JPanel());
Also notice that you must do this in the Event's Thread, to ensure this use the SwingUtilities.invokeLater or the SwingWorker
frame.setContentPane(newContents());
frame.revalidate(); // frame.pack() if you want to resize.
Remember, Java use 'copy reference by value' argument passing. So changing a variable wont change copies of the reference passed to other methods.
Also note JFrame is very confusing in the name of usability. Adding a component or setting a layout (usually) performs the operation on the content pane. Oddly enough, getting the layout really does give you the frame's layout manager.
Hope this piece of code give you an idea of changing jPanels inside a JFrame.
public class PanelTest extends JFrame {
Container contentPane;
public PanelTest() {
super("Changing JPanel inside a JFrame");
contentPane=getContentPane();
}
public void createChangePanel() {
contentPane.removeAll();
JPanel newPanel=new JPanel();
contentPane.add(newPanel);
System.out.println("new panel created");//for debugging purposes
validate();
setVisible(true);
}
}
On the user action:
// you have to do something along the lines of
myJFrame.getContentPane().removeAll()
myJFrame.getContentPane().invalidate()
myJFrame.getContentPane().add(newContentPanel)
myJFrame.getContentPane().revalidate()
Then you can resize your wndow as needed.
Game game = new Game();
getContentPane().removeAll();
setContentPane(game);
getContentPane().revalidate(); //IMPORTANT
getContentPane().repaint(); //IMPORTANT
It all depends on how its going to be used. If you will want to switch back and forth between these two panels then use a CardLayout. If you are only switching from the first to the second once and (and not going back) then I would use telcontars suggestion and just replace it. Though if the JPanel isn't the only thing in your frame I would use
remove(java.awt.Component) instead of removeAll.
If you are somewhere in between these two cases its basically a time-space tradeoff. The CardLayout will save you time but take up more memory by having to keep this whole other panel in memory at all times. But if you just replace the panel when needed and construct it on demand, you don't have to keep that meory around but it takes more time to switch.
Also you can try a JTabbedPane to use tabs instead (its even easier than CardLayout because it handles the showing/hiding automitically)
The other individuals answered the question. I want to suggest you use a JTabbedPane instead of replacing content. As a general rule, it is bad to have visual elements of your application disappear or be replaced by other content. Certainly there are exceptions to every rule, and only you and your user community can decide the best approach.
Problem: My component does not appear after I have added it to the container.
You need to invoke revalidate and repaint after adding a component before it will show up in your container.
Source: http://docs.oracle.com/javase/tutorial/uiswing/layout/problems.html
I was having exactly the same problem!! Increadible!! The solution I found was:
Adding all the components (JPanels) to the container;
Using the setVisible(false) method to all of them;
On user action, setting setVisible(true) to the panel I wanted to
show.
// Hiding all components (JPanels) added to a container (ex: another JPanel)
for (Component component : this.container.getComponents()) {
component.setVisible(false);
}
// Showing only the selected JPanel, the one user wants to see
panel.setVisible(true);
No revalidate(), no validate(), no CardLayout needed.
The layout.replace() answer only exists/works on the GroupLayout Manager.
Other LayoutManagers (CardLayout, BoxLayout etc) do NOT support this feature, but require you to first RemoveLayoutComponent( and then AddLayoutComponent( back again. :-) [Just setting the record straight]
I suggest you to add both panel at frame creation, then change the visible panel by calling setVisible(true/false) on both.
When calling setVisible, the parent will be notified and asked to repaint itself.
class Frame1 extends javax.swing.JFrame {
remove(previouspanel); //or getContentPane().removeAll();
add(newpanel); //or setContentPane(newpanel);
invalidate(); validate(); // or ((JComponent) getContentPane()).revalidate();
repaint(); //DO NOT FORGET REPAINT
}
Sometimes you can do the work without using the revalidation and sometimes without using the repaint.My advise use both.
Just call the method pack() after setting the ContentPane, (java 1.7, maybe older) like this:
JFrame frame = new JFrame();
JPanel panel1 = new JPanel();
JPanel panel2 = new JPanel();
....
frame.setContentPane(panel1);
frame.pack();
...
frame.setContentPane(panel2);
frame.pack();
...
To put it simple, there's a simple java swing app that consists of JFrame with some components in it. One of the components is a JPanel that is meant to be replaced by another JPanel on user action.
So, what's the correct way of doing such a thing? I've tried
panel = new CustomJPanelWithComponentsOnIt();
parentFrameJPanelBelongsTo.pack();
but this won't work. What would you suggest?
Your use case, seems perfect for CardLayout.
In card layout you can add multiple panels in the same place, but then show or hide, one panel at a time.
1) Setting the first Panel:
JFrame frame=new JFrame();
frame.getContentPane().add(new JPanel());
2)Replacing the panel:
frame.getContentPane().removeAll();
frame.getContentPane().add(new JPanel());
Also notice that you must do this in the Event's Thread, to ensure this use the SwingUtilities.invokeLater or the SwingWorker
frame.setContentPane(newContents());
frame.revalidate(); // frame.pack() if you want to resize.
Remember, Java use 'copy reference by value' argument passing. So changing a variable wont change copies of the reference passed to other methods.
Also note JFrame is very confusing in the name of usability. Adding a component or setting a layout (usually) performs the operation on the content pane. Oddly enough, getting the layout really does give you the frame's layout manager.
Hope this piece of code give you an idea of changing jPanels inside a JFrame.
public class PanelTest extends JFrame {
Container contentPane;
public PanelTest() {
super("Changing JPanel inside a JFrame");
contentPane=getContentPane();
}
public void createChangePanel() {
contentPane.removeAll();
JPanel newPanel=new JPanel();
contentPane.add(newPanel);
System.out.println("new panel created");//for debugging purposes
validate();
setVisible(true);
}
}
On the user action:
// you have to do something along the lines of
myJFrame.getContentPane().removeAll()
myJFrame.getContentPane().invalidate()
myJFrame.getContentPane().add(newContentPanel)
myJFrame.getContentPane().revalidate()
Then you can resize your wndow as needed.
Game game = new Game();
getContentPane().removeAll();
setContentPane(game);
getContentPane().revalidate(); //IMPORTANT
getContentPane().repaint(); //IMPORTANT
It all depends on how its going to be used. If you will want to switch back and forth between these two panels then use a CardLayout. If you are only switching from the first to the second once and (and not going back) then I would use telcontars suggestion and just replace it. Though if the JPanel isn't the only thing in your frame I would use
remove(java.awt.Component) instead of removeAll.
If you are somewhere in between these two cases its basically a time-space tradeoff. The CardLayout will save you time but take up more memory by having to keep this whole other panel in memory at all times. But if you just replace the panel when needed and construct it on demand, you don't have to keep that meory around but it takes more time to switch.
Also you can try a JTabbedPane to use tabs instead (its even easier than CardLayout because it handles the showing/hiding automitically)
The other individuals answered the question. I want to suggest you use a JTabbedPane instead of replacing content. As a general rule, it is bad to have visual elements of your application disappear or be replaced by other content. Certainly there are exceptions to every rule, and only you and your user community can decide the best approach.
Problem: My component does not appear after I have added it to the container.
You need to invoke revalidate and repaint after adding a component before it will show up in your container.
Source: http://docs.oracle.com/javase/tutorial/uiswing/layout/problems.html
I was having exactly the same problem!! Increadible!! The solution I found was:
Adding all the components (JPanels) to the container;
Using the setVisible(false) method to all of them;
On user action, setting setVisible(true) to the panel I wanted to
show.
// Hiding all components (JPanels) added to a container (ex: another JPanel)
for (Component component : this.container.getComponents()) {
component.setVisible(false);
}
// Showing only the selected JPanel, the one user wants to see
panel.setVisible(true);
No revalidate(), no validate(), no CardLayout needed.
The layout.replace() answer only exists/works on the GroupLayout Manager.
Other LayoutManagers (CardLayout, BoxLayout etc) do NOT support this feature, but require you to first RemoveLayoutComponent( and then AddLayoutComponent( back again. :-) [Just setting the record straight]
I suggest you to add both panel at frame creation, then change the visible panel by calling setVisible(true/false) on both.
When calling setVisible, the parent will be notified and asked to repaint itself.
class Frame1 extends javax.swing.JFrame {
remove(previouspanel); //or getContentPane().removeAll();
add(newpanel); //or setContentPane(newpanel);
invalidate(); validate(); // or ((JComponent) getContentPane()).revalidate();
repaint(); //DO NOT FORGET REPAINT
}
Sometimes you can do the work without using the revalidation and sometimes without using the repaint.My advise use both.
Just call the method pack() after setting the ContentPane, (java 1.7, maybe older) like this:
JFrame frame = new JFrame();
JPanel panel1 = new JPanel();
JPanel panel2 = new JPanel();
....
frame.setContentPane(panel1);
frame.pack();
...
frame.setContentPane(panel2);
frame.pack();
...
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'm working on an online mode for a new game and in order to prevent cheating I need fix window sizes (and both players need a window with the same sizes).
I used 'jframe.setResizable(false);' but it seems to be "glitchy".
When I click the window and move it away from the border of the screen, Windows does minimize it.
Here's a video about it:
http://www.youtube.com/watch?v=AQ7OHJOuLSk&feature=youtu.be
I've tried following code in order to fix it:
Dimension d = new Dimension(width, height);
panel.getJFrame().setMaximumSize(d);
panel.getJFrame().setMinimumSize(d);
panel.setMaximumSize(d);
panel.setMinimumSize(d);
and I created a Component Listener:
if (max_height!=-1){
if (e.getComponent().getSize().getHeight()>max_height){
e.getComponent().setSize((int) e.getComponent().getSize().getWidth(),max_height);
}
}
if (max_width!=-1){
if (e.getComponent().getSize().getHeight()>max_width){
e.getComponent().setSize(max_width,(int) e.getComponent().getSize().getHeight());
}
and I tried to work with Layouts but nothing worked.
What I need now is either the possibility to prevent that minimize "glitch" (If it is a glitch) or a way to make the JPanel not resizable. Like when the size of the JFrame window is changed, the JPanel always stays the same. It's neither streched nor minimized.
Help is much appreciated :)
Sincerely Felix
So far the best patch for this annoying issue is the following. Doesn't matter where you call the setResizable(false) method. Just add this piece of code after you setVisible(true).
private void sizeBugPatch() {
while (frame.getWidth() > yourWidth) {
frame.pack();
}
}
Where yourWidth is the width you've set in any of the possible ways, either manually or by overriding setPreferredSize methods. The explanation is quite easy, frame.pack() seems to reset frame.setResizable(boolean b) somehow. You could use an if instead of the while loop but I prefer while to exclude the case the window would still be extra-sized even after a second pack().
Did you initialize the variable jframe or are you calling the general Class?
Because if you do it like this:
JFrame frame = new JFrame();
frame.setResizable(false);
It works fine for me...
Here I go again... battling with swings!!! So I'm creating an online test which will be displayed in an applet. The number of questions in the tests isn't fixed, so I need to ask questions according to the test. In order to display the questions I created a question jpanel that then I added to container panel which be displayed in the applet. For the container panel I'm using a boxlayout that allows me to stack questions one on top of the other.
My issue is that after adding more than 5 questions to the container panel the questions start overlapping. So can anyone guide me?
First, how can I avoid the overlapping?
Second, does a jpanel have a fixed maximum size? Or is there a way I can make it big enough to fit all the test question in the panel container? I thought about embedding the panel in a jscrollpane or I don't know if once the container panel is embedded in the applet it will scroll down as I scroll down the browser... Thank you guys for any help
Here's a pic of what it looks like when there aren't many questions...
Here is the code...
public class Test extends JPanel {
public Test() {
setLayout(null);
JScrollPane scrollPane = new JScrollPane();
scrollPane.setBounds(0, 5, 712, 1200);
add(scrollPane);
JPanel panel = new JPanel();
scrollPane.setViewportView(panel);
panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
MultipleChoice q1 = new MultipleChoice();
panel.add(q1);
MultipleChoice q2 = new MultipleChoice();
panel.add(q2);
MultipleChoice q3 = new MultipleChoice();
panel.add(q3);
MultipleChoice q4 = new MultipleChoice();
panel.add(q4);
MultipleChoice q5 = new MultipleChoice();
panel.add(q5);
}
}
I'm guessing, and all I can do is guess without an sscce, but if your MultipleChoice JPanel uses null layout, then it won't be able to give a decent preferredSize to your layout managers allowing for overlapping components. If so, again the solution is to not use null layout, almost ever.
You state in comment:
I know buddy... But how can I be more specific when I don't know much about swings? I'm using Windowbuilder and that's the layout given when setting a container layout to absolute.
"buddy"?
regarding, "when I don't know much about swings": then learn about Swing. Go to the Layout Manager Tutorials and read up on the layout managers.
regarding, "I'm using Windowbuilder and that's the layout given when setting a container layout to absolute.": part of your problem, as you yourself admit, is that you don't yet fully understand Swing and in particular use of its layout managers, and one reason for this problem is that you're using a tool that buffers you from having to understand this. I urge you not to use WindowBuilder. Again read up on the layout managers and learn how to use them. You will not be sorry that you've done this.