Develop Reference

JLayeredPane with JPanel

The problem: I have no control on implementing more into the histogram package, so I create an array of buttons and overlay them on top of the histogram using JLayeredPane. However, I cannot get both the histogram plot and the buttons panels to scale when the JFrame is enlarged or contracted.
The JLayedPane is composed of 2 JPanels, see MWE.
To repeat the issue, just run program and extend JFrame.
I have read the following on SO posts; jlayeredpane-with-gridlayout, jlayeredpane-with-a-layoutmanager, jlayeredpane-not-resizing-with-jframe, resize-jframe-to-jpanels-inside-jlayeredpane, automatic-content-resizing-of-jlayeredpane,
as well as the Oracle page on JLayeredPane which has some examples
As useful as these links were, I still cannot get both JPanels to extend/contract with the JFrame.
Question: Is there a way to get both JPanels in the JLayeredPane to rescale without implementing a new layout? If new layout is needed, would someone please provide a MWE on how to do such?
public class FrameDemo extends JPanel {
private JLayeredPane layeredPane;
private final int width = 800;
private final int height = 800;
private String[] layerStrings = { "Yellow (0)", "Magenta (1)", "Cyan (2)", "Red (3)", "Green (4)", "Blue (5)" };
private Color[] layerColors = { Color.yellow, Color.magenta, Color.cyan, Color.red, Color.green, Color.blue };
public FrameDemo() {
setLayout(new BorderLayout());
init();
addPanels();
add(layeredPane, BorderLayout.CENTER);
}
private void init() {
this.layeredPane = new JLayeredPane();
this.layeredPane.setPreferredSize(new Dimension(width, height));
this.layeredPane.setBorder(BorderFactory.createTitledBorder("Histogram should go here"));
this.layeredPane.setLayout(new BorderLayout());
}
private void addPanels() {
this.layeredPane.add(createHistogramPanel(), BorderLayout.CENTER, new Integer(1));
this.layeredPane.add(createButtonPanel(), BorderLayout.CENTER, new Integer(0));
this.layeredPane.addComponentListener(new ComponentAdapter() {
#Override
public void componentResized(ComponentEvent e) {
Dimension size = layeredPane.getSize(); // get size
createHistogramPanel().setSize(size); // push size through
createButtonPanel().setSize(size); // push size trhough
// otherChildOfLayers.setSize(size); // push size trhough
layeredPane.revalidate(); // revalidate to see updates
layeredPane.repaint(); // "Always invoke repaint after
// revalidate"
}
});
}
private JPanel createHistogramPanel() {
JPanel histpanel = new JPanel();
histpanel.setLayout(new GridLayout(2, 3));
for (int i = 0; i < layerStrings.length; i++) {
JLabel label = createColoredLabel(layerStrings[i], layerColors[i]);
histpanel.add(label);
}
histpanel.setOpaque(false);
histpanel.setBounds(10, 10, width, height);
return histpanel;
}
private JLabel createColoredLabel(String text, Color color) {
JLabel label = new JLabel("");
label.setVerticalAlignment(JLabel.TOP);
label.setHorizontalAlignment(JLabel.CENTER);
label.setOpaque(true);
label.setBackground(color);
label.setForeground(Color.black);
label.setBorder(BorderFactory.createLineBorder(Color.black));
label.setPreferredSize(new Dimension(120, 120));
return label;
}
private JPanel createButtonPanel() {
ButtonGroup buttons = new ButtonGroup();
JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new GridLayout(2, 3));
for (int i = 0; i < 6; i++) {
final int placer = i + 1;
JButton freshButton = new JButton();
freshButton.addActionListener(e -> {
System.out.println("Button " + placer + " clicked");
});
freshButton.setText("Button " + (i + 1));
freshButton.setOpaque(true);
freshButton.setContentAreaFilled(false);
freshButton.setBorderPainted(false);
freshButton.setBounds(new Rectangle(132, 75 + (i * 20), 40, 20));
buttonPanel.add(freshButton, null);
buttons.add(freshButton);
}
buttonPanel.setOpaque(false);
buttonPanel.setBounds(10, 10, width, height);
return buttonPanel;
}
private static void createAndShowGUI() {
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JComponent newContentPane = new FrameDemo();
newContentPane.setOpaque(true); // content panes must be opaque
frame.setContentPane(newContentPane);
frame.setLocationRelativeTo(null);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}

Your code won't work because in componentResized you're creating new panels and applying the size to them. You need to resize the existing panels added to the layered pane. This could be done by assigning histogramPanel and buttonPanel as instance variables.

JScrollPane doesn't show scroll bars when JPanel is added

I'm tried to add a JPanel to a JScrollPane using:
panel1 Panel1 = new panel1();
jScrollPane1.setViewportView(Panel1);
and it worked. But the problem is scrollPane doesn't show scroll bars even the Panel1 is bigger. (I'm working with NetBeans & panel1 is a jpanel form)

Override, getPreferredSize() method for the said JScrollPane, you might be able to see the Scroll Bar. Or one can simply call setPreferredSize(), though as stated in the API
Sets the preferred size of this component. If preferredSize is null, the UI will be asked for the preferred size
overriding will be beneficial, as it tends to define some appropriate dimensions to the said JComponent.
Something like this:
JScrollPane scroller = new JScrollPane() {
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 200);
}
};
scroller.setViewportView(panelWithScroll);
One example:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class PanelScroller {
private void displayGUI() {
JFrame frame = new JFrame("Swing Worker Example");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
JPanel contentPane = new JPanel();
JPanel panelWithScroll = new JPanel();
panelWithScroll.setLayout(new GridLayout(0, 1, 5, 5));
JScrollPane scroller = new JScrollPane() {
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 200);
}
};
scroller.setViewportView(panelWithScroll);
//scroller.setPreferredSize(new Dimension(300, 200));
for (int i = 0; i < 20; i++) {
panelWithScroll.add(new JLabel(Integer.toString(i + 1), JLabel.CENTER));
}
contentPane.add(scroller);
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
Runnable runnable = new Runnable() {
#Override
public void run() {
new PanelScroller().displayGUI();
}
};
EventQueue.invokeLater(runnable);
}
}

If you only want the scrollbars to show up you can call
JScrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
JScrollPane.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
But that don't make them work at all.
if you wont to make them work you can try to set the preferred size of the component inside the Scrollpane to larger then size of Scrollpane and then call repaint(e.g. by make the window fullscreen)

Strange JFrame size

So I set the setSize(500,500).. add some panels, the sum of panels Y is 500 like the JFrame but executing it shows an count Y of 525 am I missing something?
JPanel panel = new JPanel();
panel.setLayout(null);
getContentPane().add(panel);
//--------------------
JPanel top_panel = new JPanel();
top_panel.setLayout(null);
top_panel.setBackground(Color.blue);
top_panel.setBounds(0, 0, 500, 40);
panel.add(top_panel);
//------------------------------
JPanel middle_panel = new JPanel();
middle_panel.setLayout(null);
middle_panel.setBackground(Color.yellow);
middle_panel.setBounds(0, 40, 500, 385);
panel.add(middle_panel);
//-----------------------------
JPanel bottom_panel = new JPanel();
bottom_panel.setLayout(null);
bottom_panel.setBackground(Color.black);
bottom_panel.setBounds(0, 425, 500, 75);
panel.add(bottom_panel);
setSize(500,500);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setResizable(false);
setLocationRelativeTo(null);
40+385+75 = 500 but to show all the panels i must
setSize(500,525);
then it fits
here's an image:

The frame size is the light blue rectangle outside bounds including the title bar. Your panels are appearing in the inner bounds which is frame size less than the frame border and frame title bar. Do you see how your marked space at the bottom is strangely the same height as the title bar?
After adding your panels/component to the frame and just before calling frame.setVisible(true), call frame.pack().
It would be also preferable if you embrace a layout manager (such as FlowLayout) and when necessary call setPreferredSize and let the layout manager do the layout. Normally one would call setPreferredSize over setBound, setSize, setMininumSize, setMaximumSize.
import javax.swing.*;
import java.awt.*;
public class FrameSize {
private JFrame frame;
FrameSize create() {
frame = createFrame();
frame.getContentPane().add(createContent());
return this;
}
private JFrame createFrame() {
JFrame frame = new JFrame(getClass().getName());
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
return frame;
}
void show() {
// frame.setSize(500, 500);
frame.setResizable(false);
frame.setLocationRelativeTo(null);
frame.pack();
frame.setVisible(true);
}
private Component createContent() {
JPanel panel = new JPanel(null);
JPanel topPanel = new JPanel(null);
topPanel.setBackground(Color.blue);
topPanel.setBounds(0, 0, 500, 40);
panel.add(topPanel);
JPanel middlePanel = new JPanel(null);
middlePanel.setBackground(Color.yellow);
middlePanel.setBounds(0, 40, 500, 385);
panel.add(middlePanel);
JPanel bottomPanel = new JPanel(null);
bottomPanel.setBackground(Color.black);
bottomPanel.setBounds(0, 425, 500, 75);
panel.add(bottomPanel);
panel.setPreferredSize(new Dimension(500, topPanel.getBounds().height + middlePanel.getBounds().height + bottomPanel.getBounds().height));
return panel;
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new FrameSize().create().show();
}
});
}
}

You shouldn't be setting size or calling setSize(...) or setBounds(...) as that's setting you up for similar problems in the future, or worse problems when you try to show your GUI on a different platform. Instead let the preferredSizes of your components and the layout managers do this work for you. If you absolutely must set the size of a component, then override getPreferredSize() and return a Dimension that is calculated to work for you. And yes, as per javajon, you should call pack() on the JFrame before displaying it.
For more discussions on the null layout, please read what one of the best Swing experts on this site, MadProgrammer, has to say in his answer here.

How to get a JScrollPane to resize with its parent JPanel

My question is similar to this one (How to get JScrollPanes within a JScrollPane to follow parent's resizing), but that question wasn't clear and the answer there didn't help me..
I have this SSCCE (using MigLayout):
public static final int pref_height = 500;
public static void main(String[] args) {
JPanel innerPanel = new JPanel(new MigLayout());
innerPanel.setBorder(new LineBorder(Color.YELLOW, 5));
for(int i = 0; i < 15; i++) {
JTextArea textArea = new JTextArea();
textArea.setColumns(20);
textArea.setRows(5);
textArea.setWrapStyleWord(true);
textArea.setLineWrap(true);
JScrollPane jsp = new JScrollPane(textArea);
innerPanel.add(new JLabel("Notes" + i));
innerPanel.add(jsp, "span, grow");
}
JScrollPane jsp = new JScrollPane(innerPanel) {
#Override
public Dimension getPreferredSize() {
setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
Dimension dim = new Dimension(super.getPreferredSize().width + getVerticalScrollBar().getSize().width, pref_height);
setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
return dim;
}
};
jsp.setBorder(new LineBorder(Color.green, 5));
JPanel outerPanel = new JPanel();
outerPanel.setBorder(new LineBorder(Color.RED, 5));
outerPanel.add(jsp);
JFrame frame = new JFrame();
JDesktopPane jdp = new JDesktopPane();
frame.add(jdp);
jdp.setPreferredSize(new Dimension(800, 600));
frame.pack();
JInternalFrame jif = new JInternalFrame("Title", true, true, true, true);
jif.pack();
jif.add(outerPanel);
jdp.add(jif);
jif.pack();
jif.setVisible(true);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
I want the JScrollPane to resize whenever the parent JPanel is resized. Basically, I want the green border to line up with the red border. Right now, the green border stays the same size no matter the red border (unless you resize too small).

JPanel outerPanel = new JPanel();
A JPanel uses a FlowLayout by default which always respects the size of the component added to it. As a guess, maybe you can use:
JPanel outerPanel = new JPanel( new BorderLayout() );
A BorderLayout give all the space available to the component added to the panel. By default a JInternalFrame also uses a BorderLayout. So since all the parent components of your scroll pane use a BorderLayout all the space should go to the scroll pane.
When you post a SSCCE you should post code using classes from the JDK that simulates your problem so that everybody can test your SSCCE.

I noticed this did not have an answer that uses the original layout so here is one.
In order to make the JScrollPane resize when the parent JPanel is resized you need to do two things.
1) Set the layout of the panel to grow. This can be using the following code.
new MigLayout("", //Layout Constraints
"grow", //Column Constraints
"grow"); //Row Constraints
2) Set the component to grow. This is as simple as adding an extra argument in the add() function.
add(jsp, "grow");
ExtraIn order to make the JTextArea column grow when you resize the JScrollPane you can change the layout to only make the second column change. For example
new MigLayout("", //Layout Constraints
"[/*Column 1*/][grow /*Column 2*/]", //Column Constraints
""); //Row Constraints
Also, I would recommend you use wrap instead of span to use the next row as span refers using so many columns. For example span 2 //Means use 2 columns for this component. This would mean when you add your jsp to innerPanel it would become
innerPanel.add(jsp, "wrap, grow");
Edited SSSCE
import java.awt.*;
import javax.swing.*;
import javax.swing.border.*;
import net.miginfocom.swing.MigLayout;
public class JSPR extends JFrame {
public static final int pref_height = 500;
public static void main(String[] args) {
JPanel innerPanel = new JPanel(new MigLayout("", "[][grow]", ""));
innerPanel.setBorder(new LineBorder(Color.YELLOW, 5));
for(int i = 0; i < 15; i++) {
JTextArea textArea = new JTextArea();
textArea.setColumns(20);
textArea.setRows(5);
textArea.setWrapStyleWord(true);
textArea.setLineWrap(true);
JScrollPane jsp = new JScrollPane(textArea);
innerPanel.add(new JLabel("Notes" + i));
innerPanel.add(jsp, "wrap, grow");
}
JScrollPane jsp = new JScrollPane(innerPanel) {
#Override
public Dimension getPreferredSize() {
setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
Dimension dim = new Dimension(super.getPreferredSize().width + getVerticalScrollBar().getSize().width, pref_height);
setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
return dim;
}
};
jsp.setBorder(new LineBorder(Color.green, 5));
JPanel outerPanel = new JPanel(new MigLayout("", "grow", "grow"));
outerPanel.setBorder(new LineBorder(Color.RED, 5));
outerPanel.add(jsp, "grow");
JFrame frame = new JFrame();
JDesktopPane jdp = new JDesktopPane();
frame.add(jdp);
jdp.setPreferredSize(new Dimension(800, 600));
frame.pack();
JInternalFrame jif = new JInternalFrame("Title", true, true, true, true);
jif.pack();
jif.add(outerPanel);
jdp.add(jif);
jif.pack();
jif.setVisible(true);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}

Stack swing elements from top to bottom

Consider the following figure:
I need to develop a swing GUI the looks like this. I simply named them jLabel's but there a few images and jLabels in it. The default awt background visible is a JPanel and each red background visible is a serperate JPanel. Now I need them to get stacked as shown above. I tried a number of LayoutManagers and still it doesn't work.
The important point here is that the number of red colored divs are not constant. If there is only one red colored div then it must be displayed at the top, not at the center. As far as i know GridBagLayout should work, but it centers the single red colored jpanel available. All the layout managers are centering them but not stacking them from top to bottom.

Even with anchor set to NORTH then the panels will still be centered. You could work around it by adding a dummy panel to fill the remaining space. Personally I'd stay well away from GridBagLayout though.
JFrame frame = new JFrame();
JPanel content = new JPanel();
content.setBorder(BorderFactory.createLineBorder(Color.red));
frame.setContentPane(content);
frame.getContentPane().setLayout(new GridBagLayout());
frame.setSize(400, 300);
for (int i = 0; i < 3; i++) {
JPanel panel = new JPanel();
panel.add(new JLabel("label1"));
panel.add(new JLabel("label2"));
panel.add(new JLabel("label3"));
panel.setBorder(BorderFactory.createLineBorder(Color.red));
GridBagConstraints con = new GridBagConstraints();
con.gridy = i;
con.gridx = 0;
con.anchor = GridBagConstraints.NORTHWEST;
con.ipady = 10;
frame.getContentPane().add(panel, con);
}
// dummy panel to use up the space (force others to top)
frame.getContentPane().add(
new JPanel(),
new GridBagConstraints(0, 3, 1, 1, 1, 1,
GridBagConstraints.NORTHWEST,
GridBagConstraints.VERTICAL, new Insets(0, 0, 0, 0), 0,
0));
frame.setVisible(true);
GroupLayout example (my favourite layout manager).
JFrame frame = new JFrame();
JPanel content = new JPanel();
frame.setContentPane(content);
frame.getContentPane().setLayout(
new BoxLayout(content, BoxLayout.Y_AXIS));
frame.setSize(400, 300);
GroupLayout gLayout = new GroupLayout(content);
content.setLayout(gLayout);
ParallelGroup hGroup = gLayout.createParallelGroup();
gLayout.setHorizontalGroup(hGroup);
SequentialGroup vGroup = gLayout.createSequentialGroup();
gLayout.setVerticalGroup(vGroup);
for (int i = 0; i < 3; i++) {
JPanel panel = new JPanel();
panel.add(new JLabel("label1"));
panel.add(new JLabel("label2"));
panel.add(new JLabel("label3"));
panel.setBorder(BorderFactory.createLineBorder(Color.red));
hGroup.addComponent(panel);
vGroup.addComponent(panel, GroupLayout.PREFERRED_SIZE,
GroupLayout.PREFERRED_SIZE, GroupLayout.PREFERRED_SIZE);
vGroup.addGap(10);
}
frame.setVisible(true);

you can use Vertical BoxLayout, for example:
http://www.java-tips.org/java-se-tips/javax.swing/how-to-use-swing-boxlayout.html

nobody tell us that all JComponents must be visible, for example
from code
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.LineBorder;
public class AddComponentsAtRuntime {
private JFrame f;
private JPanel panel;
private JCheckBox checkValidate, checkReValidate, checkRepaint, checkPack;
public AddComponentsAtRuntime() {
f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
panel = new JPanel(new GridLayout(0, 1));
f.add(panel, "Center");
f.add(getCheckBoxPanel(), "South");
f.setLocation(200, 200);
f.pack();
f.setVisible(true);
}
private JPanel getCheckBoxPanel() {
checkValidate = new JCheckBox("validate");
checkValidate.setSelected(false);
checkReValidate = new JCheckBox("revalidate");
checkReValidate.setSelected(false);
checkRepaint = new JCheckBox("repaint");
checkRepaint.setSelected(false);
checkPack = new JCheckBox("pack");
checkPack.setSelected(false);
JButton addComp = new JButton("Add New One");
addComp.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
JPanel b = new JPanel(new GridLayout(0, 4));
b.setBackground(Color.red);
b.setBorder(new LineBorder(Color.black, 2));
//b.setPreferredSize(new Dimension(600, 20));
for (int i = 0; i < 4; i++) {
JLabel l = new JLabel("label" + i + 1);
b.add(l);
if (i == 2) {
l.setVisible(false);
}
}
panel.add(b);
makeChange();
System.out.println(" Components Count after Adds :" + panel.getComponentCount());
}
});
JButton removeComp = new JButton("Remove One");
removeComp.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
int count = panel.getComponentCount();
if (count > 0) {
panel.remove(0);
}
makeChange();
System.out.println(" Components Count after Removes :" + panel.getComponentCount());
}
});
JPanel panel2 = new JPanel();
panel2.add(checkValidate);
panel2.add(checkReValidate);
panel2.add(checkRepaint);
panel2.add(checkPack);
checkPack.setSelected(true);
panel2.add(addComp);
panel2.add(removeComp);
return panel2;
}
private void makeChange() {
if (checkValidate.isSelected()) {
panel.validate();
}
if (checkReValidate.isSelected()) {
panel.revalidate();
}
if (checkRepaint.isSelected()) {
panel.repaint();
}
if (checkPack.isSelected()) {
f.pack();
}
}
public static void main(String[] args) {
AddComponentsAtRuntime makingChanges = new AddComponentsAtRuntime();
}
}

You should try the MigLayout it is simple yet powerful. Below I tell miglayout to grow elements, and fill all possible space, then after each element I tell it to go to a new line (wrap). You can find examples and tutorial on MigLayout page http://www.miglayout.com/:
import net.miginfocom.swing.MigLayout;
public class PanelLearning extends JPanel {
public PanelLearning() {
setLayout(new MigLayout("", "[grow, fill]", ""));
for (int i = 0; i < 3; i++) {
JPanel panel = new JPanel();
panel.add(new JLabel("label1"));
panel.add(new JLabel("label2"));
panel.add(new JLabel("label3"));
panel.setBorder(BorderFactory.createLineBorder(Color.red));
add(panel, "span, wrap");
}
}
public static void main(String[] args) {
JFrame frame = new JFrame("Login");
frame.setVisible(true);
frame.setContentPane(new PanelLearning());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.pack();
}
}

Make sure GridBagConstraints.anchor = GridBagConstraints.NORTH when you add components to the panel.