I'm programming my very first GUI app in Java using the Swing framework. I've coded a basic login system using the JTextField, JPasswordField, and JButton classes. Now, I'm writing the actionPerformed method for the button, which I want to remove these items as they are no longer necessary, but I am unsure as to the best way of achieving this.
I've considered using the setVisible method of these components, which seems to work, but I'm sure that's not the preferred way of doing it. Sorry if this is a bit of a dumb question..
Have your login dialog separated from your main window. When you finished with the login, just hide the login dialog.
You can also save your text fields and buttons into a class field, and later call remove(Component) for each one.
Generally, you would want to be able to do this in one line of code. So, you should consider wrapping the different things you'd like to show or hide in a JPanel. Then, you can dynamically show or hide the JPanels.
You could have a login JPanel, which is set up and displayed and once the user's password is verified, you can show your application JPanel. This can easily be done using a CardLayout.
It treats each component in the container as a card. Only one card is visible at a time, and the container acts as a stack of cards.
Here is a tutorial.
Using a CardLayout, your code could look something like this:
instance variables:
static final String LOGINPANEL = "LOGINPANEL";
static final String MAINPANEL = "MAINPANEL";
JPanel cards;
where your panels are created:
JPanel loginPanel = new JPanel();
//add your stuff to the login panel
JPanel mainPanel = new JPanel();
//add your stuff to the main panel
cards = new JPanel(new CardLayout());
cards.add(loginPanel, LOGINPANEL);
cards.add(mainPanel, MAINPANEL);
then when your password is verified, in the AWT thread, you can do this:
CardLayout cl = (CardLayout)(cards.getLayout());
cl.show(cards, MAINPANEL);
I agree with JPanel suggestion. Add the log-in components to a JPanel, then hide the JPanel once there is a log-in.
I will suggest you to use a JDialog for your login. After a successful login you just need to call “dialog.dispose()” and then load your interface.
If the application you are building need to display several windows you should consider to use a JDesktopPane (http://java.sun.com/j2se/1.5.0/docs/api/javax/swing/JDesktopPane.html)
Related
I have a JFrame and a few JPanels that are displayed depending on where the user goes (to login, homepage etc), is there a way to set all JPanels to the same size without having to manually specify?
public mainApp() {
main = new JFrame("Application");
main.setSize(640, 480);
main.setVisible(true);
}
private JPanel loginScreen() {
login = new JPanel(null);
login.setSize(640, 480);
login.setVisible(true);
}
For example I have 5 different JPanels, and have to specify the size in each, is there a way to set a default size that is the same as the JFrame?
You have different valid options here. Knowing that you want to change from one view to another and keep the same size, it sounds like the best option would be to use a CardLayout allowing you to change between the different views without having to worry about repainting and revalidating stuff (this tutorial from Oracle helped me a lot back when I was learning to use this layout: Oracle - How to use CardLayout.
However, as usual with Swing/AWT this is not the only valid option. For example, you could also use the BorderLayout that is applied by default to the ContentPane from the JFrame and add the desired JPanel to the Center of that BorderLayout. However, you would have to manage the view-changing process in this case.
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 have a JFrame and it has a JPanel. In my JPanel class, I have some combo-boxes, and a button. What I would like to do is dynamically switch (I suppose repaint() - am I right?) my JPanel is based on those combo-boxes and button. So simply creating two panels and making one opaque or whatever, won't work. I would really appreciate if someone provided me with some guidance. I would like to do this in the simplest way possible. I would also like all buttons/combo-boxes and whatever else to carry over into this new background.
The easiest way would be just to call setBackground(Color):
Example:
JPanel myPanel = new JPanel();
myPanel.setBackground(Color.RED);
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