Develop Reference

Set the size of visible space in a JFrame

I have had this problem a few times before, and I finally attempted to solve it, but I cannot fond the right solution. I have a simple JFrame program. The basic JFrame code looks like this:
JFrame frame = new JFrame("halp");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500,500);
frame.setResizable(false);
frame.setVisible(true);
Here's an image of what I'm trying to accomplish:
As you can see, there's space taken up by the top bar and the borders of the window. One way to fix this is to increase the size of the window, but that isn't neat at all, and also not every system has the same border sizes of the window.
I've done research and tried a few things I found on earlier asked questions:
frame.pack(). This method only set the window to minimal size, as if I didn't set the size at all.
frame.getContentPane().setSize(500,500);. The window still has the borders counted in the frame size.
frame.setPreferredSize(new Dimension(500, 500)); and JPanel.setPreferredSize(new Dimension(500, 500));. The frame went into minimum size, as with frame.pack().
I tried combining these methods, but nothing seemed to work.
What am I missing? Is there another aspect of the JFrame I need to add? Is it an incompatibility issue of BlueJ?

frame.getContentPane().setPreferredSize(new Dimension(500,500));
followed by a
frame.pack();
should solve your problem.

How do I switch between multiple JPanels on one main JPanel with a JButton? [duplicate]

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();
...

Java - placing items in JPanel like in JFrame

I try to do simple game, made of few 'screens' (menu, options, etc), which could work by displaying and hiding several JPanels. When I add some stuff on each panel and run the program, the only thing that appears is empty JFrame. I've made id looking like this:
public class Frame extends JFrame{
JPanel panel1 = new JPanel();
JFrame frame = new JFrame("halo");
JButton button = new Button();
int WIDTH=600,HEIGHT=600;
public Frame(){
frame.add(game);
frame.setSize(WIDTH, HEIGHT);
frame.setVisible(true);
frame.setResizable(false);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(panel1);
panel1.setBounds(0,0,WIDTH,HEIGHT)
panel1.add(button);
button.setBounds(10,10,30,30);
}}
Everything essential is imported and declared, it's just 'simpled' version. What's wrong with it?

A few things:
Using the classname Frame may conflict with java.awt.Frame.
You have to set the frame visible by calling frame.setVisible(true); Before that, call frame.pack();
You are subclassing JFrame, but also declaring and preparing a different JFrame. Eliminate one of them.
Add the components to the content pane of the JFrame: frame.getContentPane().add(subcomponent);

Setting a layout manager and packing after adding elements should fix the issue. Also it's unclear why you're referring to frame when you're constructing this. Try this version:
public class Frame extends JFrame{
JPanel panel1 = new JPanel();
JButton button = new Button();
int WIDTH=600,HEIGHT=600;
public Frame(){
setTitle("Halo");
setLayout(new BorderLayout());
add(panel1, BorderLayout.CENTER);
panel1.setBounds(0,0,WIDTH,HEIGHT);
panel1.setLayout(new BorderLayout());
panel1.add(button, BorderLayout.SOUTH);
button.setBounds(10,10,30,30);
pack();
setVisible(true);
setResizable(false);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}

JFrame uses a BorderLayout by default, this means that only one component can occupy each of the five available positions that BorderLayout managers.
By default, if you don't specify where you want the component to be, it will be added to the CENTRE position
You should break your UI down into logical units and use JPanels to manage them
You can use a combination of panels and layouts to generate complex UIs
You should also consider using a CardLayout to allow you to switch between base views
You should also call setVisible on the JFrame last, after you've established the basic UI, otherwise you'll need to call revalidate and and repaint to update the UI
You should avoid using setBounds/setSize/setLocation on components and rely on the use of layout managers, as they are designed to manage the differences in rendering pipelines that occurs across multiple different operating systems and hardware platforms

Putting a JLabel on top of a JLabel in Java

I would like to know how to put a JLabel on top of another JLabel at a specific position, in a class that extends JPanel in Java. People have asked for help with this before but the solutions that I found do not satisfy me. I am using GridLayout, here is some of my code:
//imports
public class Game extends JPanel implements MouseListener {
Icon background = new ImageIcon(getClass().getResource("/background.jpg"));
Icon foreground = new ImageIcon(getClass().getResource("/foreground.jpg"));
JLabel backgr = new JLabel(background);
JLabel foregr = new JLabel(foreground);
JFrame frame = new JFrame("Game");
public Game() {
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new GridBagLayout());
backgr.addMouseListener(this);
frame.setLayout(new FlowLayout());
frame.setPreferredSize(new Dimension(200,200));
frame.pack();
frame.setVisible(true);
frame.addMouseListener(this);
backgr.setLayout(new BorderLayout());
frame.add(backgr);
backgr.add(foreground);
}
}
(I have a lot of other methods in this class, such as some mouse stuff, but I don't include them here since they are not relevant to this problem.)
Currently the code almost works as I want, the foreground picture is displayed on top of the background, right in the middle of it. But I would like the foreground picture to be displayed at specific coordinates on the background picture. I thought that if I wanted to display the foreground at coordinates (50, 50), I could say backgr.add(foreground, 50,50), this compiles but returns an error when I run the program. Any tips of what to do? It would be really appreciated.
Edit: I discovered that by saying backgr.setLayout(null), backgr.add(foregr) and then foregr.setLocation(50,50), we can do what I was looking for. But since not using a layout manager is discouraged, I am looking for better solutions, so that I can use the coordinates on the backgr Icon.

People have asked for help with this before but the solutions that I found do not satisfy with me since they require me to set the frame layout to null, but I am using GridBagLayout
The frame is using a GridBagLayout.
You are adding the foreground JLabel, so the background JLabel. The background label can use any layout (including null) that you wish.
the foreground picture is displayed on top of the background, right in the middle of it.
That is because you are using a BorderLayout and are adding the foreground to the CENTER, which is the default when you don't specify a constraint.

Why doesnt frame show up with its title?

i have created FlowLayoutEx with some operations.then tried to put them into frame in standart way.
public static void main(String args[]){
FlowLayoutEx applet=new FlowLayoutEx();
JFrame frame=new JFrame("HW2LayoutSettings");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(applet,BorderLayout.PAGE_END);
applet.init();
applet.start();
frame.setSize(400,300);
frame.pack();
frame.setVisible(true);
}

It probably does show up, but maybe it's too small or an Exception was thrown before, it's impossible to know without knowing what your FlowLayoutEx class is.
But when you call pack() you set the window to a size corresponding to the preferred size of its components. It means:
Your previous call to setSize is useless since the size is set again by the call to pack
Your custom component should be set a preferred size.

What is the preferred size (re getPreferredSize()) of applet? Could it be (0, 0)? Is the JFrame using a BorderLayout? I think that is the default, but I'm not sure. Try setting it yourself: frame.setLayout(new BorderLayout()). Not sure about BorderLayout.PAGE_END - I always use BorderLayout.CENTER (for the main, or only, component in a JFrame).