I'm prgramming a simple input diagram in Swing. I use boxLayout to create a simple GUI of user input. Problem is that creating a horizontal strut between the JPanel of all the labels and the JPanel of the JTextFields causes the whole panel to shift downwards (weird) this is the whole panel:
private JPanel secondCard() {
//main panel. set the boxlayout
secondCard = new JPanel();
secondCard.setLayout(new BoxLayout(secondCard,BoxLayout.Y_AXIS));
// create vertical strut for looks
secondCard.add(Box.createVerticalStrut(20));
// create title. center it.
JLabel title = new JLabel("Configure main network parameters ");
title.setAlignmentX(CENTER_ALIGNMENT);
secondCard.add(title);
// create vertical strut for looks
secondCard.add(Box.createVerticalStrut(20));
// create panel for the description labels
JPanel labelPanel = new JPanel();
labelPanel.setLayout(new BoxLayout(labelPanel,BoxLayout.Y_AXIS));
labelPanel.setAlignmentX(LEFT_ALIGNMENT);
JLabel inPut =new JLabel("number of inputs");
inPut.setAlignmentX(LEFT_ALIGNMENT);
labelPanel.add(inPut);
inPut =new JLabel("number of outputs");
inPut.setAlignmentX(LEFT_ALIGNMENT);
labelPanel.add(inPut);
inPut =new JLabel("number of layers");
inPut.setAlignmentX(LEFT_ALIGNMENT);
labelPanel.add(inPut);
JPanel textFieldPanel = new JPanel();
textFieldPanel.setLayout(new BoxLayout(textFieldPanel,BoxLayout.Y_AXIS));
textFieldPanel.setAlignmentX(LEFT_ALIGNMENT);
JTextField inputTextField = new JTextField();
inputTextField.setAlignmentX(LEFT_ALIGNMENT);
textFieldPanel.add(inputTextField);
inputTextField.setMinimumSize(new Dimension(0,0));
inputTextField = new JTextField();
inputTextField.setAlignmentX(LEFT_ALIGNMENT);
textFieldPanel.add(inputTextField);
inputTextField.setMinimumSize(new Dimension(0,0));
inputTextField = new JTextField();
inputTextField.setAlignmentX(LEFT_ALIGNMENT);
textFieldPanel.add(inputTextField);
inputTextField.setMinimumSize(new Dimension(0,0));
textFieldPanel.setMaximumSize(new Dimension(50, labelPanel.getMaximumSize().height));
JPanel inputPanel = new JPanel();
inputPanel.setLayout(new BoxLayout(inputPanel,BoxLayout.X_AXIS));
inputPanel.setAlignmentX(CENTER_ALIGNMENT);
inputPanel.add(labelPanel);
//this is the problem strut!! it causes inputPanel to shift downwards
inputPanel.add(Box.createHorizontalStrut(20));
inputPanel.add(textFieldPanel);
secondCard.add(inputPanel);
return secondCard;
}
without the strut it looks like:
With strut it looks like (I know I suck at picture editing):
You are adding a Box strut to a BoxLayout.
As the javadoc states, createHorizontalStrut(int width):
Creates an invisible, fixed-width component. In a horizontal box, you
typically use this method to force a certain amount of space between
two components. In a vertical box, you might use this method to force
the box to be at least the specified width. The invisible component
has no height unless excess space is available, in which case it takes
its share of available space, just like any other component that has
no maximum height.
As such, it is filling the height between your title JLabel and the bottom of the JPanel.
You might want to consider using Box.createRigidArea(new Dimension(20, height)) instead, where height could be specified or set to the height of labelPanel.
Or, you could reconsider the layout for your JPanel - take a look at the visual guide.
For future reference, if you cannot make sense of your Swing layout, try putting adding a coloured LineBorder to the JComponents you're unsure of. In this case, the Box struts are not JComponents but Components, so you'd have to put them into a JPanel, but this would at least have shown you what space each component was taking up in your top-level JPanel.
use Cardlayout for wizard logics
put JLabel(Configure ...., JLabel.CENTER) to the BorderLayout.NORTH
put JPanel with JButtons to the BorderLayout.SOUTH
put JPanel with SpringLayout, GridLayout, or GridBagLayout to the BorderLayout.CENTER
Top-Level Container have got implemened BorderLayout by default, then there no reason to re_define BorderLayout
above mentioned steps are called NestedLayout
alternative are put all JComponents by using GridBagLayout, SpringLayout or todays MigLayout to the one JPanel, but why bothering
Example of a nested layout, one using BorderLayout, FlowLayout (JPanel's default), and GridBagLayout:
import java.awt.BorderLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.util.HashMap;
import java.util.Map;
import javax.swing.*;
public class LayoutFoo {
private static final String TITLE = "Configure Main Foobar Parameters";
private static final String[] LABEL_TEXTS = {
"Number of Spams", "Number of Frapzats", "Number of Zignuts"
};
private static final int TEXTFIELD_SIZE = 10;
private static final Insets WEST_INSETS = new Insets(5, 5, 5, 10);
private static final Insets EAST_INSETS = new Insets(5, 10, 5, 5);
private static final int EB_GAP = 5;
private Map<String, JTextField> textFieldMap = new HashMap<String, JTextField>();
public JPanel getConfigFooPanel() {
JPanel textFieldPanel = new JPanel(new GridBagLayout());
for (int i = 0; i < LABEL_TEXTS.length; i++) {
addTextAndField(textFieldPanel, LABEL_TEXTS[i], i);
}
int blVertGap = 20;
JPanel borderLayoutPanel = new JPanel(new BorderLayout(0, blVertGap));
borderLayoutPanel.setBorder(BorderFactory.createEmptyBorder(EB_GAP, EB_GAP,
EB_GAP, EB_GAP));
JLabel titleLabel = new JLabel(TITLE, JLabel.CENTER);
borderLayoutPanel.add(titleLabel, BorderLayout.PAGE_START);
borderLayoutPanel.add(textFieldPanel, BorderLayout.CENTER);
JPanel outerWrapperFlowPanel = new JPanel();
outerWrapperFlowPanel.add(borderLayoutPanel);
return outerWrapperFlowPanel;
}
public String getFieldText(String labelText) {
JTextField field = textFieldMap.get(labelText);
if (field == null) {
return ""; // ?? throw exception
} else {
return field.getText();
}
}
private void addTextAndField(JPanel panel, String text, int i) {
JLabel label = new JLabel(text, JLabel.LEFT);
JTextField textField = new JTextField(TEXTFIELD_SIZE);
textFieldMap.put(text, textField);
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = i;
gbc.gridwidth = 1;
gbc.gridheight = 1;
gbc.weightx = 1.0;
gbc.weighty = 1.0;
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.anchor = GridBagConstraints.WEST;
gbc.insets = WEST_INSETS;
panel.add(label, gbc);
gbc.gridx = 1;
gbc.anchor = GridBagConstraints.EAST;
gbc.insets = EAST_INSETS;
panel.add(textField, gbc);
}
private static void createAndShowGui() {
JFrame frame = new JFrame("LayoutFoo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new LayoutFoo().getConfigFooPanel());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
Related
I am trying to make a text editor with a button that appears at the bottom right of the editor regardless if you scroll up or down and appears over the text area
import javax.swing.*;
import java.awt.*;
public class Problem{
public static void main(String[] args){
//Setting up the frame
JFrame window = new JFrame();
window.setSize(600, 400);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Making the LayeredPane
JLayeredPane LP = new JLayeredPane();
LP.setLayout(new BorderLayout());
//Making the ScrollPane and JTextArea
JTextArea textArea = new JTextArea(100,50);
textArea.setText("Test Text");
JScrollPane back = new JScrollPane();
back.setViewportView(textArea);
//Making the panel that appears in the front of the text
JPanel front = new JPanel();
front.setLayout(null);
front.setBackground(new Color(0,0,0,0));
front.setOpaque(false);
JButton button = new JButton("test");
button.setBounds(200,200,50,20);
front.add(button);
LP.add(back,BorderLayout.CENTER);
LP.setLayer(back,0,0);
LP.add(front,BorderLayout.CENTER);
LP.setLayer(front,1,0);
window.add(LP);
window.setVisible(true);
}
}
I am seeing just the JButton with a white background, if I don't add the second layer "front" I see my back JScrollPane with the JTextArea
Caveat
I'm not a fan of this is idea. It's not a "common" UX concept that many desktop users would be presented with and there are a number of, arguably, better solutions which leverage the pre-existing experience of users.
This requires some "hacking" to get to work, so, there's no guarantee that it will work on all platforms or continue to work into the future.
Why doesn't it work?
This is a rather technical question which delves deep into the core of how Swing, and in particular, the JScrollPane work. Let's just say, I don't have the time or desire to dig into, but I know the JScrollPane is heavy optimised, which may be affecting the way in which anything which overlays it gets updated - or it could just be the way that the painting system works.
Runnable example...
This takes the idea by camickr (all credit to him), but instead of using a OverlayLayout, makes use of a GridBagLayout to position the button. Why? Because the GridBagLayout gives me more control over the position of the button - it's a personal thing.
import java.awt.*;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import javax.swing.*;
public class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setLayout(new BorderLayout());
JTextArea textArea = new JTextArea(40, 40);
try (Reader reader = new InputStreamReader(getClass().getResourceAsStream("/resources/StarWarsNewHope.txt"))) {
textArea.read(reader, "A long list");
} catch (IOException exp) {
exp.printStackTrace();
}
JButton button = new JButton("Am I in your way yet");
JPanel contentPane = new JPanel() {
#Override
public boolean isOptimizedDrawingEnabled() {
return false;
}
};
contentPane.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
gbc.weightx = 1.0;
gbc.weighty = 1.0;
// Change this to reposition the button some where else
gbc.anchor = GridBagConstraints.FIRST_LINE_END;
gbc.insets = new Insets(32, 32, 32, 32);
gbc.ipadx = 16;
gbc.ipady = 16;
contentPane.add(button, gbc);
gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
gbc.weightx = 1.0;
gbc.weighty = 1.0;
gbc.fill = GridBagConstraints.BOTH;
JScrollPane scrollPane = new JScrollPane(textArea);
contentPane.add(scrollPane, gbc);
add(contentPane);
}
}
}
You should probably also look at How to Use Scroll Panes and the section on Providing Custom Decorations for some alternatives
Swing is designed/optimized to display/paint components in 2 dimensions. The vast majority of layout managers will make sure that the components don't overlap.
This means that you can't use a layout manager on your layered pane (if you want the components to overlap). Instead, you must manually set the size/location of components on each layer.
When you use a JLayeredPane the painting of components on each layer is managed so that the higher layer is painted last.
So your code might be changed to something like:
import java.awt.*;
import javax.swing.*;
public class Main
{
public static void main(String[] args)
{
JFrame window = new JFrame();
window.setSize(600, 400);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Making the LayeredPane
JLayeredPane LP = new JLayeredPane();
//Making the ScrollPane and JTextArea
JTextArea textArea = new JTextArea(20,40);
textArea.setText("Test Text");
textArea.setSize( textArea.getPreferredSize() );
JScrollPane back = new JScrollPane( textArea);
back.setSize( textArea.getSize() );
JButton button = new JButton("test");
button.setBounds(200,200,50,20);
LP.add(back, new Integer(0));
LP.add(button, new Integer(1));
window.add(LP);
window.setVisible(true);
}
}
There is one layout manager in the JDK, the OverlayLayout, which is designed to stack components on top of one another. However, even this layout manager does not paint components properly when the components overlap. The trick when using this layout manager is to override the isOptimizedDrawing() method of the panel using the layout manager to make sure all components are repainted all the time. In this case, make sure the bottom panel is always painted before the top panel.
import java.awt.*;
import javax.swing.*;
import javax.swing.border.*;
public class Main2
{
public static void main(String[] args)
{
JFrame window = new JFrame();
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel contentPane = new JPanel()
{
#Override
public boolean isOptimizedDrawingEnabled()
{
return false;
}
};
contentPane.setLayout( new OverlayLayout(contentPane) );
JPanel top = new JPanel( new GridBagLayout() );
top.setBorder( new EmptyBorder(0, 0, 16, 16) );
top.setOpaque(false);
top.setAlignmentX(1.0f);
top.setAlignmentY(1.0f);
GridBagConstraints gbc = new GridBagConstraints();
gbc.weightx = 1.0;
gbc.weighty = 1.0;
gbc.anchor = GridBagConstraints.LAST_LINE_END;
JButton button = new JButton("test");
top.add(button, gbc);
contentPane.add(top);
//Making the ScrollPane and JTextArea
JTextArea textArea = new JTextArea(10,25);
textArea.setText("Test Text");
JScrollPane back = new JScrollPane( textArea);
back.setAlignmentX(1.0f);
back.setAlignmentY(1.0f);
contentPane.add(back);
window.add(contentPane);
window.pack();
window.setVisible(true);
}
}
The benefit of this approach is that the button will move as the frame is resized.
However, as a user I would still get annoyed with a button appearing over top of the text in my text area.
Edit:
If you really need components to overlap then I would suggest you could:
look at MadProgrammers solution to use a GridBagLayout. This approach gives far more control over the alignment of the components
check out the Overlap Layout which also provides more flexibility when aligning overlapping components
It should be noted that both above approaches may still require you to override the isOptimizedDrawEnabled(...) method to make sure components are painted properly. I am not aware of any layout manager the allows you to overlap components and works without this override.
So I've got a custom JPanel which I use multiple instances of to fill a wrapper Panel inside a JScrollPane. The number of custom JPanel elements I use is dependent on the size of a list. The problem I'm running across is a part of my Custom JPanel has another invisible JPanel which expands when I click on it's parent. The behavior I'm trying to mimic is that of an accordian UI element. Before I was on this project I was primarily a webdev and while I have worked with Java a lot, I'm still relatively new to Swing.
Here is an example of the behavior - the scroll pane with all elements closed. (forgive me for the quick paint-job comments. I tried to emphasize what I see going wrong).
Next, is the image of the first element expanded - which unexpectedly expands all other elements.
It must be noted that I'm only targeting the first panel and setting the visibility, yet all other repeating panels length grows when I do this, but obviously the components inside stay invisible.
Finally, here is my final deired result:
Is there some sort of constraint in the JScrollPane that resizes it's child JPanel's components to retain the same height at all times? I can't seem to figure a way around this and I've played with all sorts of different wrappers and layouts, all to no avail.
Please let me know if anyone wants to see code snippets, but they'll have to be heavily redacted and stripped down due to the nature of the project.
Thanks,
Marek
PS: yes, I absolutely must use Swing.
Edit: Here is a static, quick and dirty, stripped down implementation of my code as suggested by Roddy of the Frozen Peas
ExampleScrollPane:
public class ExampleSrollPane extends JPanel {
private static ExampleSrollPane instance = null;
private JScrollPane contentScrollPanel = new JScrollPane();
private Vector<ExamplePanel> exPanels;
private JPanel wrapPanel = new JPanel();
public ExampleSrollPane() {
super();
this.setLayout(new BorderLayout());
this.setBorder(BorderFactory.createBevelBorder(BevelBorder.LOWERED, Color.white,
Color.white, new Color(115, 114, 105), new Color(165, 163, 151)));
exPanels = new Vector<ExamplePanel>();
init();
}
private void init() {
contentScrollPanel.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
contentScrollPanel.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED);
contentScrollPanel.setBorder(new CompoundBorder(new EmptyBorder(5, 5, 5, 5), new SoftBevelBorder(BevelBorder.LOWERED)));
this.add(contentScrollPanel, BorderLayout.CENTER);
initPanels();
}
public void initPanels() {
int numUnits = 15;
// Init one empty panel at least
if (numUnits == 0) numUnits = 15;
wrapPanel.setLayout(new GridLayout(numUnits, 1));
for (int i = 0; i < numUnits; i++) {
ExamplePanel exPan = new ExamplePanel(i);
exPanels.add(i, exPan);
wrapPanel.add(exPan);
}
contentScrollPanel.setPreferredSize(new Dimension(575, 100));
contentScrollPanel.getViewport().add(wrapPanel);
}
/**
* Method: viewPanel()
*
*/
private static void viewPanel() {
JFrame frame = new JFrame();
frame.setLayout(new BorderLayout());
frame.setLocationRelativeTo(null);
frame.add(getInstance());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setSize(new Dimension(600, 350));
frame.setAlwaysOnTop(true);
frame.setVisible(true);
}
public static ExampleSrollPane getInstance() {
if (instance == null) {
instance = new ExampleSrollPane();
}
return instance;
}
/**
* The main method.
*
* #param args the arguments
*/
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
viewPanel();
}
});
}
}
It's here in the showHideTable method which creates the problem.
ExamplePanel (my custom JPanel):
public class ExamplePanel extends JPanel implements ActionListener {
private static final long serialVersionUID = 1L;
private static final Border STAT_BORDER = BorderFactory.createBevelBorder(BevelBorder.LOWERED, Color.white,
Color.white, new Color(115, 114, 105), new Color(165, 163, 151));
public static final EmptyBorder PAD_BORDER = new EmptyBorder(10, 10, 10, 10);
public int indx;
private JLabel unitLabel;
private JLabel statLabel;
private JLabel invLabel;
private JLabel targetLabel;
private JLabel timeLabel;
// Custom BasicArrowButton to expand/hide the "table"
private UnitToggleButton unitToggleButton;
// The expandable JPanel
public ExpanableTable elementTable;
private String id;
private String unitStatusString;
private String invStatusString;
private String targetString;
private String timeString;
public Color componentColor;
private JPanel topPanel = new JPanel();
public JPanel tablePanel = new JPanel();
public ExamplePanel(int index) {
super();
this.indx = index;
id = "Unit # 00000";
id = "Unit #00000";
unitStatusString = "PENDING";
invStatusString = "PENDING";
elementTable = new ExpanableTable();
targetString = "AZ501";
timeString = "11:18:27";
componentColor = this.getBackground();
init();
}
private void init() {
topPanel.setLayout(new GridBagLayout());
topPanel.setBorder(PAD_BORDER);
unitLabel = new JLabel(id); // TODO unit.getID();
statLabel = new JLabel(unitStatusString); // TODO: unit.getStatus();
invLabel = new JLabel(invStatusString); // TODO: unit.getInventoryStatus();
targetLabel = new JLabel(targetString);
timeLabel = new JLabel(timeString);
buildLabel(statLabel);
buildLabel(invLabel);
buildLabel(targetLabel);
buildLabel(timeLabel);
unitToggleButton = new UnitToggleButton(BasicArrowButton.EAST, indx);
GridBagConstraints gbc = new GridBagConstraints();
gbc.anchor = GridBagConstraints.FIRST_LINE_START;
gbc.fill = GridBagConstraints.FIRST_LINE_END;
gbc.gridx = 0;
gbc.gridy = 0;
gbc.weightx = .1;
gbc.weighty = 1;
gbc.insets = new Insets(0, 0, 5, 0);
// Add toggle button far-left, row 1
topPanel.add(unitToggleButton, gbc);
// Add empty space far-left, row 2
gbc.gridy = 1;
topPanel.add(new JLabel(" "), gbc);
// Add unit label row 1 column 2
gbc.gridy = 0;
gbc.gridx = 1;
gbc.weightx = .3;
topPanel.add(unitLabel, gbc);
// Add Status label row 1 column 3
gbc.gridx = 2;
topPanel.add(statLabel, gbc);
// Add inventory label row 1 column 4
gbc.gridx = 3;
topPanel.add(invLabel, gbc);
// Add tasking label row 2 column 2
gbc.gridy = 1;
gbc.gridx = 1;
topPanel.add(new JLabel(" Tasking: "), gbc);
// Add target label row 2 column 3
gbc.gridx = 2;
topPanel.add(targetLabel, gbc);
// Add mission Label row 2 column 4
gbc.gridx = 3;
topPanel.add(timeLabel, gbc);
gbc.gridx = 0;
gbc.gridy = 2;
gbc.weighty = 1;
gbc.weightx = 1;
gbc.gridwidth = 4;
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.insets = new Insets(0, 0, 0, 0);
JSeparator sep = new JSeparator(JSeparator.HORIZONTAL);
topPanel.add(sep, gbc);
gbc.gridy = 3;
topPanel.add(elementTable, gbc);
revalidate();
this.setLayout(new BorderLayout());
this.add(topPanel, BorderLayout.NORTH);
this.add(tablePanel, BorderLayout.CENTER);
HSIUtils.setColoredBorder(tablePanel, Color.RED);
tablePanel.add(elementTable);
// Do NOT show the table on initialization
tablePanel.setVisible(false);
unitToggleButton.addActionListener(this);
}
/**
* Method: buildLabel()
*
* #param label
*/
private void buildLabel(JLabel label) {
label.setBorder(STAT_BORDER);
label.setMinimumSize(new Dimension(80, 20));
label.setPreferredSize(new Dimension(100, 25));
label.setOpaque(true);
label.setHorizontalAlignment(SwingConstants.CENTER);
label.setHorizontalTextPosition(SwingConstants.CENTER);
label.setBackground(componentColor);
}
private void showHideTable(boolean show) {
tablePanel.setVisible(!show);
}
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == this.unitToggleButton) {
showHideTable(unitToggleButton.isExpanded());
}
}
}
ExpandableTable:
public class ExpanableTable extends JPanel {
public ExpanableTable () {
super();
this.setLayout(new BorderLayout());
add(new JButton("Test1"), BorderLayout.WEST);
add(new JButton("Test2"), BorderLayout.CENTER);
add(new JButton("Test3"), BorderLayout.EAST);
}
}
Basically I want to be able expand/show/resize each Panel inside the scroll pane independently of the others. As it currently stands, if I show a hidden Panel on one, the other panel's height grows to match but does not show the component. Very strange to me but could be my ignorance of certain Swing components and the constraints they contain.
Is there some sort of constraint in the JScrollPane that resizes it's child JPanel's components to retain the same height at all times?
A scroll pane doesn't resize anything. It only displays the component added to the scroll panes and add scroll bars when the preferred size of the component added is greater than the size of the scroll pane.
wrapPanel.setLayout(new GridLayout(numUnits, 1));
On the other hand when you use a GridLayout, then yes all components added to the grid will be resized to the size of the largest component.
So you don't want to use a GridLayout for the wrapper panel.
I would suggest you could use a GridBagLayout or a BoxLayout. As the panel.
Then I would suggest that for your expandable panel you use a BorderLayout. You add the part that is always visible to the CENTER and the expandable part to the PAGE_END. Then when you want to make the panel expand you just change the visibility of the component in the PAGE_END.
Then the layout managers will do all the work recalculating the proper size of the all the panels.
I have JTextFields and JLabels added to my JPanel (from left to right) every time the JButton is pressed. However, every new JTextField and JLabelthat is added becomes smaller and smaller. How do I fix this?
Also I would like to add a JScrollPane to the JPanel but having problems doing so.
public class MyExample
{
// Field members
static JPanel panel = new JPanel();
static Integer indexer = 1;
static List<JLabel> listOfLabels = new ArrayList<JLabel>();
static List<JTextField> listOfTextFields = new ArrayList<JTextField>();
static JScrollPane scrollPane = new JScrollPane( panel );
public static void main(String[] args)
{
// Construct frame
JFrame frame = new JFrame();
frame.setLayout(new GridBagLayout());
frame.setPreferredSize(new Dimension(2000, 2000));
frame.setTitle("My Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(scrollPane);
// Frame constraints
GridBagConstraints frameConstraints = new GridBagConstraints();
// Construct button
JButton addButton = new JButton("Add");
addButton.addActionListener(new ButtonListener());
// Add button to frame
frameConstraints.gridx = 0;
frameConstraints.gridy = 0;
frame.add(addButton, frameConstraints);
// Construct panel
panel.setPreferredSize(new Dimension(1000, 1000));
panel.setLayout(new GridBagLayout());
panel.setBorder(LineBorder.createBlackLineBorder());
// Add panel to frame
frameConstraints.gridx = 0;
frameConstraints.gridy = 1;
frameConstraints.weighty = 1;
frame.add(panel, frameConstraints);
// Pack frame
frame.pack();
// Make frame visible
frame.setVisible(true);
}
static class ButtonListener implements ActionListener
{
#Override
public void actionPerformed(ActionEvent arg0)
{
// Clear panel
panel.removeAll();
// Create label and text field
JTextField jTextField = new JTextField();
jTextField.setSize(100, 200);
listOfTextFields.add(jTextField);
listOfLabels.add(new JLabel("Label " + indexer));
// Create constraints
GridBagConstraints textFieldConstraints = new GridBagConstraints();
GridBagConstraints labelConstraints = new GridBagConstraints();
// Add labels and text fields
for(int i = 0; i < indexer; i++)
{
// Text field constraints
textFieldConstraints.gridx = i;
textFieldConstraints.fill = GridBagConstraints.HORIZONTAL;
textFieldConstraints.weightx = 0.5;
textFieldConstraints.insets = new Insets(10, 10, 10, 10);
textFieldConstraints.gridy = 1;
// Label constraints
labelConstraints.gridx = i;
labelConstraints.gridy = 0;
labelConstraints.insets = new Insets(10, 10, 10, 10);
// Add them to panel
panel.add(listOfLabels.get(i), labelConstraints);
panel.add(listOfTextFields.get(i), textFieldConstraints);
}
// Align components
GridBagConstraints c = new GridBagConstraints();
c.gridx = 0;
c.gridy = indexer;
c.weighty = 1;
panel.add(new JLabel(), c);
// Increment indexer
indexer++;
panel.updateUI();
}
}
}
However, every new JTextField and JLabelthat is added becomes smaller and smaller. How do I fix this?
panel.setPreferredSize(new Dimension(1000, 1000));
Don't set the preferred size. If the size is fixed then as you add more components they need to shrink to fit in the allowed space.
Don't attempt to set the size of any component. Let the layout manager do its job and determine the preferred size of the panel.
When creating a JTextField the code should be something like:
//JTextField jTextField = new JTextField();
JTextField jTextField = new JTextField(10);
This will allow the text field to determine its own preferred size to dispaly about 10 characters.
panel.updateUI();
Don't use updateUI(). That is used internally by Swing when you change the LAF. When you remove/add components you should be using:
panel.revalidate();
panel.repaint();
As for the JScrollPane with panel as a viewport, you should not be adding the panel to the frame at all - setting it as the viewport (like you're doing in the JScrollPane constructor) and adding the JScrollPane is sufficient. Adding the panel itself may be the cause of your problem.
As for the shrinking problem, I am still trying to understand your layout code - your use of GridBagLayout seems a tad overcomplicated to me. Maybe you can draw a simple sketch of how you would like the layout look?
I have been trying for hours to get JPanel in Java to contain these 4 other panels in this configuration (see picture)
The blue box should never change size.
The white box should never change height, can get wider though.
The dark grey box should never change widths, can get taller though.
The light grey box can get taller or wider.
Seems pretty simple to me, I did it in C# the other day and it was a breeze. Set the position, the width, height, and whether a certain side was anchored or not, boom done, I was starting to like java more than C until I ran into this.
I've tried countless combinations of GridBagLayout, multiple nested BoxLayout instances. They all seem to do very strange things, like make each panel a tiny 4 x 4 square, or there is crazy padding around them, or the ones that need to re-size with the window, don't.
Is there some kind of magic combination that can achieve this? Does the null layout do anchoring or percent dimensions.
The closest I've gotten is the bottom image with GridBagLayout, which looks good when it loads, but does that when you re-size the window.
Here is the code that got the above images
class MainPanel extends JPanel {
public MainPanel(){
this.setBackground(new Color(216,216,216));
this.setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
JPanel topTitle = new JPanel();
topTitle.setPreferredSize(new Dimension(140, 40));
topTitle.setMinimumSize(new Dimension(140, 40));
topTitle.setBackground(new Color(174, 216, 249));
c.weightx = 0.5;
c.gridx = 0;
c.gridy = 0;
this.add(topTitle,c);
JPanel mainHeader = new JPanel();
mainHeader.setPreferredSize(new Dimension(1060, 40));
mainHeader.setMinimumSize(new Dimension(1060, 40));
mainHeader.setBackground(Color.WHITE);
c.gridx = 1;
c.gridy = 0;
this.add(mainHeader,c);
JPanel sideNav = new JPanel();
sideNav.setPreferredSize(new Dimension(140, 760));
sideNav.setMinimumSize(new Dimension(140, 760));
sideNav.setBackground(new Color(110,110,110));
c.gridx = 0;
c.gridy = 1;
this.add(sideNav,c);
JPanel dataPanel = new JPanel();
dataPanel.setPreferredSize(new Dimension(1060, 760));
dataPanel.setMinimumSize(new Dimension(1060, 760));
dataPanel.setBackground(new Color(216,216,216));
c.gridx = 1;
c.gridy = 1;
this.add(dataPanel,c);
}
}
GUI at minimum size
GUI stretched wider & taller
It's all about getting appropriate resize weights & fill values..
import java.awt.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
public class FourPanelLayout {
private JComponent ui = null;
FourPanelLayout() {
initUI();
}
public void initUI() {
if (ui!=null) return;
ui = new JPanel(new GridBagLayout());
// It appears you don't want space around the panels.
// If not, commment out or remove this line.
ui.setBorder(new EmptyBorder(4,4,4,4));
// create the panels, each with a transparent image to suggest a size
JPanel bluePanel = new JPanel();
bluePanel.setBackground(Color.CYAN);
bluePanel.add(new JLabel(new ImageIcon(getTransparentImage(40, 20))));
JPanel darkGrayPanel = new JPanel();
darkGrayPanel.setBackground(Color.DARK_GRAY);
darkGrayPanel.add(new JLabel(new ImageIcon(getTransparentImage(40, 20))));
JPanel whitePanel = new JPanel();
whitePanel.setBackground(Color.WHITE);
whitePanel.add(new JLabel(new ImageIcon(getTransparentImage(40, 20))));
JPanel grayPanel = new JPanel();
grayPanel.setBackground(Color.GRAY);
grayPanel.add(new JLabel(new ImageIcon(getTransparentImage(360, 80))));
GridBagConstraints gbc = new GridBagConstraints();
gbc.fill = GridBagConstraints.BOTH;
gbc.weightx = 0.0f;
gbc.weighty = 0.0f;
gbc.gridx = 0;
gbc.gridy = 0;
ui.add(bluePanel, gbc);
gbc.weightx = .5f;
gbc.gridx = 1;
ui.add(whitePanel, gbc);
gbc.weighty = .5f;
gbc.gridy = 1;
ui.add(grayPanel, gbc);
gbc.weightx = 0f;
gbc.gridx = 0;
//gbc.gridy
ui.add(darkGrayPanel, gbc);
}
/* We use transparent images to give panels a natural size. */
private Image getTransparentImage(int w, int h) {
return new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
}
public JComponent getUI() {
return ui;
}
public static void main(String[] args) {
Runnable r = new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (Exception useDefault) {
}
FourPanelLayout o = new FourPanelLayout();
JFrame f = new JFrame(o.getClass().getSimpleName());
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
f.setLocationByPlatform(true);
f.setContentPane(o.getUI());
f.pack();
f.setMinimumSize(f.getSize());
f.setVisible(true);
}
};
SwingUtilities.invokeLater(r);
}
}
To implement this, I recommended to use FormLayout.
FormLayout is a powerful, flexible and precise general purpose layout manager. It places components in a grid of columns and rows, allowing specified components to span multiple columns or rows. Not all columns/rows necessarily have the same width/height.
Note: It good to use Windowbuilder in Eclipse or GUI Form in Intellij to automatically place and set the components properties.
Same Question, different context
It seems I was too hasty in my accepting before, since the problem is still there. The problem? JLabel takes the liberty of expanding its parent panel when content is added to it.
It's time for reproducing it per "Hovercraft full of eels"-ses suggestion, and here it is:
import java.awt.*;
import javax.swing.*;
public class TestLabel {
public static void main(String[] args) {
// Var inits
JFrame frame;
JPanel panel;
JLabel label;
Container pane;
GridBagConstraints gbc = new GridBagConstraints();
// Frame, content pane, layout inits
frame = new JFrame("Label Tester");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pane = frame.getContentPane();
pane.setLayout(new GridBagLayout());
gbc.weighty = 1;
gbc.fill = GridBagConstraints.BOTH;
// Add panels (note gbc weighty and fill carries over all instances)
gbc.weightx = 0.3;
gbc.gridx = 0;
gbc.gridy = 0;
panel = new JPanel();
panel.setBackground(Color.GREEN);
frame.add(panel,gbc);
label = new JLabel("THE PANEL IS NOW DISTORTED TO FIT THIS LABEL WHY IS THIS HAPPENING");
//label = new JLabel("");
label.setOpaque(true);
label.setBackground(Color.WHITE);
panel.add(label);
gbc.weightx = 0.7;
gbc.gridx = 1;
gbc.gridy = 0;
panel = new JPanel();
panel.setBackground(Color.RED);
frame.add(panel,gbc);
gbc.weightx = 0.3;
gbc.gridx = 0;
gbc.gridy = 1;
panel = new JPanel();
panel.setBackground(Color.BLUE);
frame.add(panel,gbc);
gbc.weightx = 0.7;
gbc.gridx = 1;
gbc.gridy = 1;
panel = new JPanel();
panel.setBackground(Color.YELLOW);
frame.add(panel,gbc);
frame.pack();
frame.setSize(800,600);
frame.setVisible(true);
}
}
Results:
As you can see, the green panel is forced wider and throws off my whole layout when text (or, in the original question, and icon) is added to it. I want my layout to remain the same weights, regardless of the content. The reason this came up is because I'm trying to add a scaled image as an icon to the label, as seen in the original question.
Incidentally, setPreferredSize() doesn't seem to work.
Is there a way to fix this?
Original Question
My JLabel element expands dramatically when I add an Icon to it. Why is this happening? Here's the applicable portion of the code:
// Show label and BG color
redLabel.setBackground(Color.RED);
redLabel.setOpaque(true);
// Grab stretched image (already loaded elsewhere in the code) and turn to icon
Img = Img.getScaledInstance(redLabel.getWidth(),12,Image.SCALE_REPLICATE);
ImageIcon icon = new ImageIcon(Img);
// This line throws everything off!
//It's commented out in the first pic, and included in the second.
redLabel.setIcon(icon);
As you can see from the first pic, I've got a label (in red) of width W. What I'm trying to do is stretch my icon to width W and put it in the label.
When I do this, the label expands (by exactly 50 pixels, I think) and also squeezes over the left edge (green). Does anyone have any idea why this is happening?
I've tried several things that are too verbose to explain but can't find the problem :-/
Your component expands because it allocates the necessary space for its Icon.
public class JLabelDemo {
private static BufferedImage bi;
public static void main(String[] args) throws IOException{
loadImage();
SwingUtilities.invokeLater(new Runnable(){
#Override
public void run() {
createAndShowGUI();
}
});
}
private static void loadImage() throws IOException{
bi = ImageIO.read(JLabelDemo.class.getResource("../resource/forever-alone.jpg"));
}
private static void createAndShowGUI(){
final JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JPanel panel = new JPanel();
panel.setBackground(Color.YELLOW);
panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
final JLabel emptyLabel = new JLabel();
final JLabel textLabel = new JLabel("This label has text only");
final JLabel textAndImageLabel = new JLabel("This label has text and image");
textAndImageLabel.setIcon(new ImageIcon(bi));
panel.add(emptyLabel);
panel.add(textLabel);
panel.add(textAndImageLabel);
frame.add(panel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
System.out.println("Empty label dimensions - " + emptyLabel.getSize());
System.out.println("Text only label dimensions - " + textLabel.getSize());
System.out.println("Image width: " + bi.getWidth() + ", Image height: " + bi.getHeight());
System.out.println("Text and image label dimensions - " +textAndImageLabel.getSize());
}
}
The following is outputted to console:
Empty label dimensions - java.awt.Dimension[width=0,height=0]
Text only label dimensions - java.awt.Dimension[width=129,height=16]
Image width: 194, Image height: 180
Text and image label dimensions - java.awt.Dimension[width=363,height=180]
Consider using a JLayeredPane to add components in layers. There are trips and traps though when doing this in matters of opacity, size and position of components added.
For example,
import java.awt.*;
import javax.swing.*;
public class TestLabel {
private static final Dimension SIZE = new Dimension(800, 600);
public static void main(String[] args) {
GridBagConstraints gbc = new GridBagConstraints();
JPanel defaultPane = new JPanel();
defaultPane.setLayout(new GridBagLayout());
gbc.weighty = 1;
gbc.fill = GridBagConstraints.BOTH;
// Add panels (note gbc weighty and fill carries over all instances)
gbc.weightx = 0.3;
gbc.gridx = 0;
gbc.gridy = 0;
JPanel panel = new JPanel();
panel.setBackground(Color.GREEN);
defaultPane.add(panel, gbc);
gbc.weightx = 0.7;
gbc.gridx = 1;
gbc.gridy = 0;
panel = new JPanel();
panel.setBackground(Color.RED);
defaultPane.add(panel, gbc);
gbc.weightx = 0.3;
gbc.gridx = 0;
gbc.gridy = 1;
panel = new JPanel();
panel.setBackground(Color.BLUE);
defaultPane.add(panel, gbc);
gbc.weightx = 0.7;
gbc.gridx = 1;
gbc.gridy = 1;
panel = new JPanel();
panel.setBackground(Color.YELLOW);
defaultPane.add(panel, gbc);
defaultPane.setSize(SIZE);
JLabel label = new JLabel("THE PANEL IS NOW DISTORTED TO FIT THIS LABEL WHY IS THIS HAPPENING");
label.setOpaque(true);
label.setBackground(Color.WHITE);
JPanel northPalettePanel = new JPanel();
northPalettePanel.setOpaque(false);
northPalettePanel.add(label);
JPanel palettePanel = new JPanel(new BorderLayout());
palettePanel.setOpaque(false);
palettePanel.setSize(SIZE);
palettePanel.setLocation(0, 0);
palettePanel.add(northPalettePanel, BorderLayout.NORTH);
JLayeredPane layeredPane = new JLayeredPane();
layeredPane.setPreferredSize(SIZE);
layeredPane.add(defaultPane, JLayeredPane.DEFAULT_LAYER);
layeredPane.add(palettePanel, JLayeredPane.PALETTE_LAYER);
JFrame frame = new JFrame("Label Tester");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(layeredPane, BorderLayout.CENTER);
frame.pack();
frame.setVisible(true);
}
}
Java swing is pretty old for me but if I remember well, setting a preferred size (setPreferredSize()) sometime solve these kind of problem ... Also try top lay with setMaximumSize and setMinimumSize.
You can maybe find more information in java documentation:
http://download.oracle.com/javase/tutorial/uiswing/layout/using.html#sizealignment
Regards!