I'm trying to do the following and I'm not sure what type of Java layout to use.
I want a JFrame with a single panel totalPanel. totalPanel should contain two panels which are custom classes I write, PanelA and PanelB. PanelA starts out with height 200 and PanelB starts out with height 400. When the user expands the window or resizes the window, only PanelB should increase in height, but both panels can increase in width.
How can I set this up? I've tried to use BorderLayout but then "North" is always too small in height. I've tried to use BoxLayout but then both PanelA and PanelB are always the same height.
Consider having totalPanel use a BorderLayout. Add the PanelA to the BorderLayout.PAGE_START position and the PanelB to the BorderLayout.CENTER position.
For more on the layout managers, please review the tutorial: Lesson: Laying Out Components Within a Container
Edit: I see that you've used BorderLayout, that it "doesn't work" but you don't show code. For more fine tuning on why it doesn't work, consider showing us code.
To get it to work consider giving your PanelX classes getPreferredSize() overrides that would help set the initial sizes of the JPanels.
For example:
import java.awt.BorderLayout;
import java.awt.Dimension;
import javax.swing.*;
public class SimpleGuiLayout {
private static void createAndShowGui() {
JPanel totalPanel = new JPanel(new BorderLayout());
totalPanel.add(new PanelX(800, 200, "Panel A"), BorderLayout.PAGE_START);
totalPanel.add(new PanelX(800, 400, "Panel B"), BorderLayout.CENTER);
JFrame frame = new JFrame("Simple Gui Layout");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(totalPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class PanelX extends JPanel {
private int prefW;
private int prefH;
public PanelX(int prefW, int prefH, String title) {
this.prefW = prefW;
this.prefH = prefH;
setBorder(BorderFactory.createTitledBorder(title));
}
#Override
public Dimension getPreferredSize() {
return new Dimension(prefW, prefH);
}
}
If run, it would look like so:
And would resize appropriately.
One approach (probably not the simplest) would be a GridBagLayout.
Use the weightx and weighty constraints to control which members can resize.
I recommend a GridBagLayout. It is complex to use, but it can solve your problem. Assuming panelA is on top of panelB, you would have the following constraints:
panelA and panelB's gridx would be 0
panelA would be ad gridy 0, and panelB at gridy 1
for both, you would set fill = BOTH
but to have only panelB increase in height, you would set panelB's weighty to 1.0, and panelA's to 0
You originally solution using BorderLayout will work already, you just need to set preferred height of panelA:
panelA.setPreferredSize(new Dimension(0, 200));
The width doesn't matter because BorderLayout will ignore preferred width of component added to NORTH or SOUTH.
Related
I have a JPanel with layout set to null and the background is white. Then I added that JPanel to JScrollPane.
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
public class TestJScollPane extends JPanel {
private static final long serialVersionUID = 1L;
public TestJScollPane() {
initUI();
}
private void initUI()
{
JScrollPane scrollPane = new JScrollPane();
scrollPane.getViewport().setBackground(Color.GRAY);
scrollPane.setBounds(1, 1, 200, 200);
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
setBorder(BorderFactory.createEtchedBorder(Color.GREEN, Color.MAGENTA));
setBackground(Color.WHITE);
setLayout(null);
JFrame frame = new JFrame();
scrollPane.setViewportView(this);
frame.add(scrollPane);
frame.setLayout(null);
frame.setVisible(true);
frame.setSize(800, 500);
frame.getContentPane().setBackground(Color.BLACK);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(30,30);
}
public static void main(String[] args)
{
new TestJScollPane();
}
}
My scenario is I have a zoom tool that if I zoom out the JPanel and all its shapes that were painted were scaled using AffineTransform. So I expect that if I zoom out, the background of JScrollPane was color gray but the actual was color white.
Apologies, I added a sample. Actually, this is not the actual code I created this so that I can provide a sample for you guys to help me.
I set the preferred size of JPanel to 30x30 so I expect that the background of JScrollPane will become visible but it was not.
Thanks in advance for any help.
By default the panel is sized to fit the viewport so you will not see the background of the viewport.
You need to implement the Scrollable interface of your JPanel to tell the scroll pane you want the panel displayed at its preferred size.
Or, instead of implementing the Scrollable interface yourself you can use the Scrollable Panel which, by default, will display the panel at its preferred size.
Changes to your code would be:
ScrollablePanel panel = new ScrollablePanel();
panel.setPreferredSize( new Dimension(30, 30) );
panel.setBorder(BorderFactory.createEtchedBorder(Color.GREEN, Color.MAGENTA));
panel.setBackground(Color.WHITE);
//panel.setLayout(null);
scrollPane.setViewportView(panel);
//scrollPane.setViewportView(this);
Change:
scrollPane.setViewportView(this);
To something like:
JPanel centerPanel = new JPanel(new GridBagLayout());
centerPanel.add(this);
scrollPane.setViewportView(centerPanel);
A GridBagLayout (by default, unless configured otherwise) will respect the preferred size of the child components and won't stretch them to fill the 'cell'. A scroll pane on the other hand, will stretch the content to (at least) fill the visible area.
Result:
But seriously, drop the use of null layouts. If the effect cannot be achieved using an existing layout (inbuilt or 3rd party) or a combination of layouts, it must have such esoteric positioning constraints that it deserves a custom layout manager.
The following code describes a button that is instantiated in a JPanel with a BoxLayout in Page Axis:
private class AddInputSetButton extends JButton {
public AddInputSetButton() {
super("+");
setMinimumSize(new Dimension(100, 100));
pack();
addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
addInputGroup();
}
});
}
}
I have tried setSize(), setPreferredSize(), and setMinimumSize() to no avail, none of them resize the button. I am still relatively new to Java GUIs, so hopefully it is something simple.
How do I adjust the size of the button?
EDIT: After further inspection, setPreferredSize() changes the size of the JPanel containing the buttons to the right size, but the buttons remain the same size.
JButtons (and a few other components) can be a bit goofy in layout managers. The layout manager is noticing that your button has a preferred size that needs to be respected, so it's adjusting your pane to accommodate. But your JButton is happy doing it's thing (what it thinks is right) unless you really force it to consider the size it's supposed to be.
If you're manually sizing your button (which isn't necessarily recommended), I'd say you should set all three properties (Minimum, maximum, and preferred). Maximum is the key - it forces the button to consider the other two sizes.
Here's a simple example that should work.
import java.awt.Dimension;
import javax.swing.*;
public class ButtonSizes {
private static class AddInputSetButton extends JButton {
Dimension d;
public AddInputSetButton(int width, int height) {
super("+");
d = new Dimension(width, height);
setMinimumSize(d);
setMaximumSize(d);
setPreferredSize(d);
}
}
public static void main(String[] args) {
Box buttons = Box.createVerticalBox();
buttons.add(new AddInputSetButton(100,100));
buttons.add(new AddInputSetButton(200,200));
buttons.add(new AddInputSetButton(300,300));
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(buttons);
frame.pack();
frame.setVisible(true);
}
}
For a GUI application I am creating in Java, I have the following:
A JFrame, set to have a minimum size of (300,200)
A JSplitPane, in which lies:
On the left, a JScrollPane (containing a JTree) with a minimum size of (100,0) (I only want to restrict the width to 200)
On the right, a JPanel with a minimum size of (200,0)
The sizing does not give me any issue under the following conditions:
Resizing the JSplitPane all the way to the left (to the JScrollPane's minimum size), and subsequently resize the window afterward
Just resizing the window, to a certain degree
The problem occurs when I move the JSplitPane too close to the right, whereupon resizing the window the JPanel in the right of the JSplitPane fails to adhere to the minimum width I set.
I attempted setting a maximum width on the JScrollPane, which did not seem to help at all.
Is there something involving maximum sizes I must do? Or perhaps there is a way to attach a Listener to one of the panels to force my desired behavior? Ultimately, I just want the right panel in the JSplitPane to never be less than 200px wide.
Here is an example with behavior I am experiencing:
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTree;
public class ResizeTest
{
private JFrame frame;
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
try
{
ResizeTest window = new ResizeTest();
window.frame.setVisible(true);
}
catch(Exception e)
{
e.printStackTrace();
}
}
});
}
public ResizeTest()
{
initialize();
}
private void initialize()
{
frame = new JFrame();
frame.setMinimumSize(new Dimension(300, 200));
frame.setBounds(100,100,450,300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(new GridLayout(0, 1, 0, 0));
JSplitPane splitPane = new JSplitPane();
frame.getContentPane().add(splitPane);
JScrollPane scrollPane = new JScrollPane();
scrollPane.setMinimumSize(new Dimension(100, 0));
splitPane.setLeftComponent(scrollPane);
JTree tree = new JTree();
tree.setMinimumSize(new Dimension(100, 0));
scrollPane.setViewportView(tree);
JPanel panel = new JPanel();
panel.setMinimumSize(new Dimension(200, 0));
splitPane.setRightComponent(panel);
}
}
Update:
I'm afraid I don't fully understand the point trying to be made in the proposed solutions, except for that setPreferred() and setMinimum/Maximum() are better to be avoided.
My question in response to learning this is, what are my options for restricting the JSplitPane divider outside of using these methods? MadProgrammer mentioned listening for the componentResized event, but I need just a little more clarification as to why. Am I calling setDividerLocation() in response to this event?
I apologize in advance if the appended question is meant as a separate StackOverflow question entirely, I can post another and link here if necessary.
Update 2:
Is simply not regulating how the user chooses to size the window and having the right panel in a JScrollPane a viable option? This looks to me like somewhat of a standard practice.
Firstly, the method setMinimumSize is a suggestion to the LayoutManager API. A suggestion that may be ignored.
In order to be able to even come close to supporting this, you will need to use something like a ComponentListener and monitor the componentResized event.
The best solution I can think of is to use a LayoutManager that actually uses the minimum and maximum size constraints, something like GridBagLayout.
Use this on a "content" pane and place you're JSplitPane onto this (setting it's minimum and maximum size accordingly) then add the "content" pane to frame.
UPDATE
Sorry, I'm probably missing something really obvious, but I put this little test together, I hope it has some ideas that help :P
public class TestFrameSize extends JFrame {
public TestFrameSize() throws HeadlessException {
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(600, 600);
setLocationRelativeTo(null);
setMinimumSize(new Dimension(250, 250));
JLabel left = new JLabel("Left");
JLabel right = new JLabel("Right");
Dimension pSize = new Dimension(100, 100);
Dimension mSize = new Dimension(25, 100);
left.setPreferredSize(pSize);
left.setMinimumSize(mSize);
right.setPreferredSize(pSize);
right.setMinimumSize(mSize);
JSplitPane pane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, left, right);
JPanel content = new JPanel(new GridBagLayout());
content.add(pane);
setLayout(new BorderLayout());
add(content);
}
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
new TestFrameSize().setVisible(true);
}
}
In this example, the preferred size of the content of a JSplitPane is initially set to a small multiple of the component's preferred size in getPreferredSize(). Note that the JSplitPane will become no smaller than the panel's minimum size, managed by the enclosed Jlabel.
Is it possible to have some extra space around the edges of a JFrame that uses AbsoluteLayout? When I have a button as the downwardsmost component on the JFrame, it gets positioned right up against the bottom edge of the JFrame window, and it looks bad. I would like to know if there's a way to add a little extra space between components and the edge of the JFrame while using AbsoluteLayout.
Suggestions:
When you add a component to a JFrame, you're actually adding it to the JFrame's contentPane. To give the contentPane a "buffer" border, consider giving it an EmptyBorder(...) with the parameters being int constants for the amount of border desired around the component.
Avoid using "absolute" layouts for anything, and especially for placing components at easy to place locations for the layout managers, such as at the bottom of the GUI.
For example, note in the GUI created in the code below how the center and bottom JPanel's don't go out to the edge of the GUI because of the empty border:
import java.awt.BorderLayout;
import java.awt.Dimension;
import javax.swing.*;
public class ButtonAtBottom {
private static void createAndShowGui() {
JPanel bottomPanel = new JPanel();
bottomPanel.add(new JButton("Bottom Button"));
bottomPanel.setBorder(BorderFactory.createTitledBorder("Bottom Panel"));
JPanel centerPanel = new JPanel();
centerPanel.setBorder(BorderFactory.createTitledBorder("Center Panel"));
JPanel mainPanel = new JPanel(new BorderLayout());
mainPanel.add(centerPanel, BorderLayout.CENTER);
mainPanel.add(bottomPanel, BorderLayout.PAGE_END);
// **** here I add the border to the mainPanel which I'll
// make into the contentPane
int eb = 25;
mainPanel.setBorder(BorderFactory.createEmptyBorder(eb, eb, eb, eb));
// don't set the preferredSize per Kleopatra, but am doing it
// here simply to make code shorter for this sscce
mainPanel.setPreferredSize(new Dimension(500, 400));
JFrame frame = new JFrame("ButtonAtBottom");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
You can use Box.createRigidArea(dimensions) to create an empty space that you can add below the button.
Set an empty border on your content panel where SIZE is the amount of padding you want.
JFrame frame = new JFrame();
JPanel panel = new JPanel(null);
panel.setBorder(BorderFactory.createEmptyBorder(SIZE,SIZE,SIZE,SIZE);
frame.setContentPane(panel);
//The rest
The arguments are for top, left, bottom and right padding so if you want different paddings on each edge, you can set it accordingly.
I am learning how to use Swing and found myself quite difficult task.
What I am trying to accomplish: I want to have panel (call it menu panel) on the left side (let's say 100px width) and the second panel (call it content panel), which takes the rest of available place.
In menu panel there are 3 buttons. When I press on of them, to the right side of menu panel (over content panel) second menu panel (submenu) should appear (and it should start in the middle of button which was pressed).
It may be hard to understand, so I've created simple draft:
I tried JLayeredPane but there were problems with resizing window (elements in Layered Pane didn't resize).
JLayeredPane miss implementations for LayoutManager, you have to setPreferredSize or setBounds manually for sizing/place JComponents,
there is one possible workaround you can add ComponentListener to the JFrame, then on componentResized(ComponentEvent e) you can resize/replace JComponent(s) to the desired Bounds
for example
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
public class LayeredPaneWithOverlap {
private JTextArea textArea = new JTextArea(2, 10);
private JPanel textPanel = new JPanel(new BorderLayout());
private JTable table = new JTable(30, 5);
private JScrollPane scroll = new JScrollPane(table);
private JLayeredPane layer = new JLayeredPane();
private JFrame frame = new JFrame("Frame with resiziable JLayeredPane");
public void makeUI() {
textArea.setBorder(new LineBorder(Color.DARK_GRAY));
textArea.setText("Frame with resiziable JLayeredPane");
textPanel.setOpaque(false);
textPanel.add(textArea, BorderLayout.NORTH);
Font font = textArea.getFont();
FontMetrics fontMetrics = textArea.getFontMetrics(font);
int h = fontMetrics.getHeight() + frame.getInsets().top +
textPanel.getInsets().top + textArea.getInsets().top
+ textArea.getInsets().bottom;
scroll.setBounds(0, h, 400, 300);
layer.add(textPanel, new Integer(2));
layer.add(scroll, new Integer(1));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(600, 400);
frame.addComponentListener(new ComponentAdapter() {
#Override
public void componentResized(ComponentEvent e) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
resizeAll();
}
});
}
});
frame.setLocationRelativeTo(null);
frame.add(layer);
resizeAll();
frame.setVisible(true);
}
void resizeAll() {
Insets insets = frame.getInsets();
int w = frame.getWidth() - insets.left - insets.right;
int h = frame.getHeight() - insets.top - insets.bottom;
textPanel.setSize(w, h);
scroll.setSize(w, h - scroll.getY());
layer.revalidate();
layer.repaint();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new LayeredPaneWithOverlap().makeUI();
}
});
}
}
You can set a layoutmanager for the layered pane, javax.swing.OverlayLayout uses the full available space and allows resizing.
JLayeredPane layer = new JLayeredPane();
layer.setLayout(new OverlayLayout(layer));
You probably don't want the submenu to occupy the fullspace. To avoid it you can override its get…size-methods. Or you can add a second LayeredPane (for it's transperancy and it's layoutmanager), set a normal BoxLayout and use a spacer.
JPanel normalContents = new JPanel();
layer.add(normalContents, JLayeredPane.DEFAULT_LAYER);
JLayeredPane subMenuAuxiliaryLayer = new JLayeredPane()
subMenuAuxiliaryLayer.setLayout(new BoxLayout(subMenuAuxiliaryLayer, BoxLayout.LINE_AXIS));
layer.add(subMenuAuxiliaryLayer, JLayeredPane.PALETTE_LAYER);
JPanel submenuContents = new JPanel();
subMenuAuliliaryLayer.add(submenuContents);
subMenuAuxiliaryLayer.add(Box.createHorizontalGlue());
contentPanel.setLayout(null); // Absolute positioning of children.
#Override
public void actionPerformed(ActionEvent evt) {
final JButton btn = (JButton) evt.getSource();
final int buttonY = btn.getY(); // Must be final for usage in new Runnable object.
SwingUtilities.invokeLater(new Runnable() { // Return fast from event handling.
#Override
public void run() {
JPanel child = new JPanel();
child.setBackground(Color.RED); // So we'll see it.
child.setBounds(0, buttonY, 100, 300);
contentPanel.removeAll(); // Clear content panel of prior additions.
contentPanel.add(child); // Add a new panel.
contentPanel.repaint(10L);
}
});
}
The JLayeredPane works by defualt with no Layout manager, which means that you are using absolute positioning and no resizing. You could add a resize listener and adjust positions and size of inner components from code, as you see fit.
If you don't want to do this from code, you will need a layout manager, nothing fancy, just something to fill the container as it resizes. But here's the thing... if you add a layout manager, it will layout the components as if they are all in one layer, but most layout managers don't overlap their children so they are useless. The only one you could use is the OverlayLayout - it can also resize children. But using an OverlayLayout with JLayeredPane is overkill. You can just use OverlayLayout with a JPanel. So, yes, JLayeredPane is kind of useless. I recommend using a JPanel with an OverlayLayout instead.
Here is how to set things up so that you can have great control over almost any overlapping UI scenario out there: Using a JPanel with an OverlayLayout, have a separate transparent JPanel for each layer. In this way you can combine various LayoutManagers on different layers, by setting a diferent layout manager for each pane, including absolute positioning if necessary. Then add your visible components inside the panels representing the layers. Don't add them directly to the OverlayLayout panel. Just make sure that all of the JPanels you are using as layers have setAlignmentX and Y to center (0.5f) so that they fill the entire OverlayLayout panel as it resizes.