I've been struggling to get my JFrame to repaint its content. I've tried using both the revaluate() and repaint() methods together after I add the new components into the JFrame but I'm not seeing the frame change.
Here's the simple GUI of a minesweeper game I'm trying to make.
When a user clicks on either of the top 3 buttons, they enter the following code block
private void drawGrid()
{
removeAll();
setLayout(new GridLayout(2,1));
add(new JButton("button"));
setVisible(true);
revalidate();
repaint();
setVisible(false);
setVisible(true);
}
When clicking a button, the whole application turns white, but I can't see the new button I added. When I remove the two setVisible() method lines, then clicking a button definitely removes the components since I can't click on any of them now, but the 4 initial buttons are still visible. Removing the revalidate or repaint methods has no effect on the application.
What else can I try to get the application to refresh and display its new content.
Calling removeAll on a JFrame is dangerous and can produce unexpected results, another reason why it's discouraged to extend from or manage UI's directly on top level containers.
Start by using a JPanel as you base UI component, then use a CardLayout to manage switching between the views.
Separate each view into it's own class (extending from JPanel or something simular) for easier management
Maybe it would work better if you used this
easyBtn.setVisible( false );
medBtn.setVisible( false );
hardBtn.setVisible( false );
customBtn.setVisible( false );
newBtn.setVisible( true );
If that does not work, try putting it into a SwingWorker.
Related
i've created a JPanel with loaded components, called bkg, so I want to change it to SlideShow, that extends jpanel, and show it when i click on a button. this is the code called from the button:
public void startGame(){
bkg.removeAll();
bkg.revalidate();
bkg.repaint();
bkg = new SlideShow();
contentPane.add(bkg, BorderLayout.CENTER);
}
In the SlideShow constructor I've created some test labels, but when I click the button, all of old bkg components disappear (as I want) but nothing from SlideShow components I placed in the costructor appears... How can change the bkg JPanel to another external class that extends JPanel?
Suggestions:
Why remove/revalidate/repaint the bkg variable when you immediately replace the current object held by that variable with another?
What you want to revalidate and repaint is the contentPane after replacing the bkg object after adding it to the contentPane.
It's almost always better to use a CardLayout rather than manually swapping. The tutorial can be found here: CardLayout tutorial.
Or since it looks like you're re-starting a game, perhaps then give the SlideShow class a reset() method, one that sets both its model and its visible state to its original conditions.
So
public void startGame(){
// *** no need for this ***
// bkg.removeAll();
// bkg.revalidate();
// bkg.repaint();
bkg = new SlideShow();
contentPane.add(bkg, BorderLayout.CENTER);
// *** add this ***
contentPane.revalidate();
contentPane.repaint();
}
Or if you go the reset option, then the method would simplify to:
public void startGame(){
bkg.reset();
}
However that reset method would be key, the details depending on the structure of the rest of your program.
I'm relatively new to Java and I'm trying to make some kind of quiz. I created 3 JFrames, all in the same package. On my main frame, there are two buttons (one for the english version and the other one for the german version). I want to switch JFrames after pressing these buttons (so that I can, by pressing "English", see and interact with my english quiz frame). Looking it up didn't help me the slightest, because I'm not really experienced with it. Is it even possible to do it like this? If not, how could I do it?
The standard approach is to use the Card Layout, which allows you to use the same JFrame as you populate it with different things at different points in your application. So initially, your JFrame would show the loading screen, then the user presses a button and you load a new set of components without discarding the current JFrame you have. In some cases, you might also need to make some size adjustments.
It is difficult to say without seeing any code, but usually, what is done is that you do something like so:
new Frame(args);
this.dispose();
The code above assumes that the constructor of Frame takes care of launching and making the components visible. The this.dispose(); disposes of the current JFrame (assuming your class extends JFrame).
You have two buttons in your frame 1 right? So first, double click the button which says "English". Lets say the variable name for that button is jButton1. Inside that button type this.
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
this.dispose();
EnglishFrame eng = new EnglishFrame();
eng.setVisible(true);
}
Then double click the other button which says "German" (jButton2). Inside that type this.
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
this.dispose();
GermanFrame german = new GermanFrame();
german.setVisible(true);
}
this.dispose() - This will cause the jFrame window to close
Then you create an object of the other two forms. (In your case the form for English and Germany)
.setVisible(true) - This will show you the form.
Create a single Jframe window. After that create JPanels with all the compenents such as buttons, textfields and labels you want. Make sure the panel is the same size as your Jframe. Panel's work about the same as JFrame's, code wise.
This code will stitch everything together for you:
panel.setSize(Jframe.getSize()) //That wont
panel.add(button); //Just remember you need to add more code to position the buttons correctly.
//If you using netbeans builder:
//You just have to use this one line in the constructor/intialiser method
frame.add(panel); //This will add the panel to the Jframe/Window
//No need to add extra code for positioning.
If you want to swap between the panels. In the button press method, use this
frame.setContentPane(panel); //panel = panel you want to change too.
frame.repaint(); //Ensures that the frame swaps to the next panel and doesn't get stuck.
frame.revalidate(); //Ensures that the frame swaps to the next panel and doesn't get stuck.
When you first start the java application you have to set the content pane or else it will appear as a blank window.
frame.setContentPane(panel); //Starting Panel
frame.setVisible(true); //Make the frame visible
Sorry if the explanation is bad, I don't have enough time to explain it fully.
I'm trying to set a variable to be a new JPanel and then add it once a button is pressed, but it is not working and I don't know why.
code:
private void nextButtonActionPerformed(java.awt.event.ActionEvent evt) {
remove(scriptPanel);
scriptPanel = new GemPanel();
add(scriptPanel);
validate();
repaint();
pack();
}
GemPanel is just a JPanel class I made. When I press the next button, it re-sizes the frame to be as small as possible and nothing actually happens. If I re-size it to normal, the original scriptPanel is still there.
What gives?
Instead of trying to remove and add entire panels, a better, less problem prone approach would be to use a CardLayout that will allow to swap views. You can see more at How to use Cardlayout
Also, by the looks of your method signature, it seems you're using the Netbeans builder too. You may also want to take a look at How to Use CardLayout with Netbeans Gui Builder
I have a Gui and a Game class, and I'm unable to update the gui from the game. I'm not using threads, but I've seen it update before, so that isn't the problem. The game logic is really simple, there is no need for threads. No matter how furiously I call repaint() and revalidate(), it doesn't work now, no matter where I put it.
class Gui {
//...
public Gui(Game game) {
this.game = game;
initialize();
}
private void initialize() {
//...
okButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
okAction(textField.getText());
textField.setVisible(false);
okButton.setVisible(false);
textField.setText("");
}
});
}
private void okAction(String input) {
game.receiveInput(input);
}
public void output(String msg) {
textArea.append(msg + "\n");
}
public void getInput() {
textField.setVisible(true);
okButton.setVisible(true);
textField.setText("");
}
}
Also I want to be able to pass a String back to the game instance. I thought I'd call getInput() from the game, which will show a JTextField to type in, and a JButton to submit. In the actionPerformed() method I would just get the text entered, and call a method back in the game class. I don't know if this would work, since the gui is not updating, and I never had the input field and button appear. Is this right?
This would be the method which the gui "calls back":
class Game {
//...
public void receiveInput(String input) {
int n = Integer.parseInt(input);
if ( validInput(input, actualDecision.choices.size()) ) {
parser.setAction(actualDecision.choices.get(n-1).action);
}
}
}
From the game class, I just want to call gui.output() and gui.getInput() a few times.
Where is my problem? Why isn't it updating, nor freezing? If I use the debugger, the both output() and getInput() is executed, but nothing happens...
EDIT:
Ok I see a problem myself, with the getting input part... Since it returns quickly, it can never receive an input. But that doesn't explain why aren't the input field and the button, or any text is showing up
EDIT 2:
Oh god, sorry, I really don't know how to make it shorter, but you only ever need to look at the Game and the Gui, others are just there to compile.
The code: https://gist.github.com/anonymous/53bad714592792316b4d
An xml to test against: https://gist.github.com/anonymous/30b56facb78fe6ecd482
Honestly I have just taken a look to Gui class code and don't know why it doesn't update properly when it interacts with Game class. BUT I have several remarks on your code and I hope these can lead you in the right way by making this class simpler and then you can focus on the interaction with Game class.
Menu bar
You're adding the JMenuBar to a JPanel instead of setting it to the JFrame:
panel.add(menuBar, gbc);
//frame.setJMenuBar(menuBar); Use this instead
As JFrame is a top level container prepared to handle a menu bar you should consider make the suggested change.
Saving validate() call
As the JFrame is initialized at the start of initialize() method and the JPanel is added after making the frame visible then you have to call frame.revalidate() method to revalidate the components hierarchy. If you just initialize the panel before make the frame visible then you don't need to call revalidate() method. Take a look to this answer for further details.
Missing pack() call
There's no call to frame.pack() method to lay out the frame's subcomponents. Take a look to Window.pack().
Missing GridBagConstraints when adding okButton
There's no GridBagConstraints as argument when adding okButton to panel:
panel.add(okButton);
//panel.add(okButton, gbc); This is the correct way.
Use of setSize()
In this line:
frame.setSize(800, 600);
We should avoid using set(Preferred | Minimum | Maximum)Size() because of reasons discussed in this topic: Should I avoid the use of set(Preferred|Maximum|Minimum)Size methods in Java Swing?
Use of GridBagLayout
This is just a suggestion there's nothing wrong on how you are using GridBagLayout. As probably you have noted this layout manager is a little hard to use (and I really don't like it by the way :) You can use a Nested Layout approach to make the components layout easier and your code more readable. Maybe this approach is good enough:
Set the JMenuBar to the JFrame. It's one less component to lay out
;)
Add the scroll pane with the text area directly to the frame's
content pane using
BorderLayout
constraints: frame.getContentPane().add(scrollPane,
BorderLayout.CENTER);
Create a new JPanel to hold the text field and the button used to
ask for user's input and add it to the frame's content pane.
Translated to code:
JPanel usersInput = new JPanel(new FlowLayout(FlowLayout.CENTER));
usersInput.add(textField);
usersInput.add(okButton);
frame = new JFrame();
frame.setJMenuBar(menuBar);
frame.getContentPane().add(scrollPane, BorderLayout.CENTER);
frame.getContentPane().add(usersInput, BorderLayout.SOUTH);
frame.setTitle("Choose your own adventure");
frame.pack();
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); // It's better practice DISPOSE_ON_CLOSE ;)
frame.setVisible(true);
Update
Well I'm curious and I really want to test your game (quite nice work by the way :) The thing is I have found at least two problems in the logic:
Use of == to compare strings
In Parser class there are several string comparisons using == but this is not the proper way to compare strings. We must use .equals() method to compare strings equality. Take a look to this topic: How do I compare strings in Java?
Game.processStory() has an endless loop
This method has an endless loop here:
while ( !end() ) { // this condition never is false so the loop is infinite
...
}
Looking closer to Game.end() method I have found an incorrect string comparison:
private boolean end() {
return ( parser.getAction() == "end" );
//It should be: return parser.getAction().equals("end");
}
But fixing that doesn't solve the problem either: it turns parser.getAction() always returns "d1" and consequently it will never be equal to "end".
Having said this as Game.play() is executed in the Event Dispatching Thread (a.k.a. EDT) triggered by newGameItem menu item and Game.processStory() has this endless loop, then the EDT is getting blocked and Gui is never updated.
In this case I would suggest you take a look to Concurrency in Swing trail to learn about how to avoid blocking the EDT.
I created a JFrame Class with Netbeans 7.3 and added two panels from the palette.
I have added a button in the first panel on the click of which I want to add a new button in the second panel(topoPane).
Below is the button click event that I have written for the same. But, the button is not getting added to the panel even when the event is getting called.
Please tell me what's wrong in it.
private void jButton1MouseClicked(java.awt.event.MouseEvent evt)
{
// TODO add your handling code here:
System.out.println("Creating the Button");
JButton but = new JButton();
but.setBackground(Color.red);
but.setText("New Button");
but.setBounds(500, 500, 500, 500);
topoPane.add(but);
topoPane.revalidate();
}
From your use of setBounds, it is obvious that you are using a null layout. Because of this you need to call repaint() as containers with no layout do not automatically repaint added components on revalidate.
Apart from the fact that calling repaint is good practice, layout managers can remove the need to make this call along with manage the sizing and positioning of components. This makes it a good reason to use a layout manager.