Is there a way to add objects to a JFrame without using Layout Manager? I have tile objects(for the game 2048) that I am trying to add to a JFrame so I can call the JFrame then have a loop forever where the tiles are forever repainting themselves and I can press arrows to make them move depending on constraints(like if it can move in a specific direction.
Why I don't want to use a specific layout manager - my objects are tiles in the game 2048- which means they are constantly changing position which would mess with the layout manager setup ie flowlayout where all the JPanel objects are in a specific order and position.
Heres where I am trying to instantiate the JFrame:
public static void main(String[] args) throws InterruptedException {
//set up JFrame, tile objects
frame = new JFrame();
a = new tile(100, 100, frame);
b = new tile(200, 200, frame);
frame.addKeyListener(a);
frame.add(a);
frame.add(b);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(false);
frame.setSize(500, 500);
frame.setVisible(true);
//a loop so that it is continuously repainting and when i press a key something else happens
while(true) {
a.repaint();
b.repaint();
Thread.sleep(10);
}
It is possible to work with Swing without LayoutManager. Not using a LayoutManager allows and requires the application to have full control on the absolute position of the components.
Check out these fine resources:
https://docs.oracle.com/javase/tutorial/uiswing/layout/none.html
Java swing GUI absolute positioning
In a nutshell, creating a container without a layout manager involves the following steps:
Set the container's layout manager to null by calling setLayout(null).
Call the Component class's setBounds() method for each of the container's children.
Call the Component class's repaint() method.
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();
...
public static void main(String[] args) {
JFrame frame = new JFrame("Fantasy Football Toolkit");
frame.setContentPane(new GUI().mainPanel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(350, 475);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
Above is the main method to my GUI application. I'm wondering if I can change the size of the form after this main method runs. What if I want to change the size when I click a button? The problem is that I can't access frame. This has to be possible one way or another. I have looked all over for a solution but can't find one. Thanks.
You can always access the top level JFrame from any component that it holds via SwingUtilities.getWindowAncestor(yourComponent). This method returns a Window object, but if you are 100% sure that it's a JFrame, you can always cast it (or test it first that this is so).
Once obtained, you can always call pack() on it to resize it to the preferred sizes of the components that it contains. In general you will want to avoid setting sizes directly as that can lead to bugs later on when you modify your program.
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 am having trouble getting two different components to display at the same time.
public class BandViewer
{
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.setSize(1000, 800);
frame.setTitle("band");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
BandComponent component = new BandComponent();
ConcertBackground component1 = new ConcertBackground();
frame.add(component);
frame.add(component1);
frame.setVisible(true);
}
}
Now I read on this forum that you can do something to display both at the same time but wasn't able to figure out how it was done. Can anyone please help? I want to have one to be in front of the other. Is their some way to control the layering? Thanks in advance.
Within a JFrame a Layout Manager is usually used to position different components, tutorial here.
Something like:
Container contentPane = frame.getContentPane();
contentPane.setLayout(new FlowLayout());
To set up a a basic layout manager for your JFrame. There is also a JLayeredPane which allows you to specify a z-order - docs page, so something like:
JLayeredPane layeredPane = new JLayeredPane();
BandComponent component = new BandComponent();
ConcertBackground component1 = new ConcertBackground();
layeredPane.add(component, 0); // 0 to display underneath component1
layeredPane.add(component1, 1);
contentPane.add(layeredPane);
A display hierachy is set up in this manner, with objects within objects. I'm not sure what BandComponent and ConcertBackground classes are, but if they inherit from Swing classes you might have to set a preferred size or similar to ensure they don't have a zero size!
The problem you are having is because JFrame by default uses a BorderLayout. BorderLayout only allows a single component to appear in any one of it's five available positions.
To add multiple components to a single container, you need to configure the layout or use one which better meets your needs...
Take a look at A Visual Guide to Layout Managers for more examples
I have a hybrid swing application which can be run as applet or java application with the following structure:
public class Gui extends JApplet {
public void init() {...}
public void paint(Graphics g) {
...
g.drawImage(image, 0, 0, this);
}
public static void main(String args[]) {
JFrame frame = new JFrame();
JDialog dialog = new JDialog(frame);
Gui gui = new Gui();
gui.init();
gui.start();
dialog.add("Center", gui);
...
}
}
The whole gui consists of one drawing area which is continously updated.
I would like to embed a panel which is always on top and independent of the underlying drawing process.
I tried using JLayeredPane and add it between JDialog and JApplet, but Japplet cant be added to the Pane because it is a top level container.
I also tried realising it with the glasspane but no success at all.
Is there a solution without refactoring to much since the structure should be kept as far as possible.
Don't override paint() of a top level container, like JApplet or JFrame. Custom painting is done by overriding the paintComponent() method of a JPanel (or JComponent). Then you add the panel to the frame.
dialog.add("Center", gui);
The is not the way to add a component to a panel. Read the Container API to find the proper add(...) method to use. Also don't hardcode string values. Every layout manager contains variables that can be used as the constraint values.
I would like to embed a panel which is always on top and independent of the underlying drawing process.
Not sure this makes sense. If the panel is always on top, then it would cover the painting.
I tried using JLayeredPane
That sounds like the proper approach. You add the layered pane to the frame or applet. Then you can have a background painting panel and another transparent panel on top. Read the Swing tutorial on Using Layered Panes for a working example.