I would like to dynamically place buttons in a JPanel. For that, I chose to apply a GridBagLayout to this panel (the one to contain the buttons).
the problem is that my buttons appear from the center of my panel while I would like them to be placed from top to bottom.
here is my code:
void placerListeUsers(){
jPanel49.setLayout(new GridBagLayout());
//jPanel49 est le panel sur lequel je place mes boutons.
//jPanel49 est placé dans une JScrollPane
GridBagConstraints c = new GridBagConstraints();
c.gridx = 0;
c.fill = GridBagConstraints.HORIZONTAL;
//c.anchor=GridBagConstraints.NORTH;
c.weightx = 1;
//c.weighty = 0;
for (int i = 0; i < 5; i++) {
c.gridwidth = GridBagConstraints.REMAINDER;
c.gridy = i;
jPanel49.add(new JButton("Super"), c);
}
and what he produces:
thank you for helping me fix this problem
the problem is that my buttons appear from the center of my panel while I would like them to be placed from top to bottom.
You need to specify weightx/y constraints, otherwise the components gather in the middle.
Read the Swing tutorial on How to Use GridBagLayout. The section on Specifying Constraints will give you more information.
It looks to me like you just have vertical buttons. Maybe a GridLayout or BoxLayout added to the BorderLayout.PAGE_START of the frame would be easier.
Even though you did not provide a MCVE as requested. I try to provide a solution for your layout... ;)
The problem is, as already mentioned by camickr, you need to tell GridBagLayout where to put all the extra space of your Panel after calculating the size of the buttons:
anchor has to be GridBagConstraints.NORTH.
weighty needs to be set to 1 for the last button added to your panel.
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.addWindowListener(new WindowAdapter() {
#Override
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
Container content = frame.getContentPane();
GridBagLayout layout = new GridBagLayout();
JPanel panel = new JPanel(layout);
GridBagConstraints c = new GridBagConstraints();
c.gridx = 0;
c.fill = GridBagConstraints.HORIZONTAL;
c.anchor = GridBagConstraints.NORTH;
c.weightx = 1;
int buttonCount = 5;
for (int i = 0; i < buttonCount; i++) {
c.weighty = i == buttonCount - 1 ? 1 : 0;
c.gridwidth = GridBagConstraints.REMAINDER;
c.gridy = i;
JButton button = new JButton("Super");
panel.add(button, c);
}
content.add(new JScrollPane(panel));
frame.pack();
frame.setSize(400, 400);
frame.setVisible(true);
}
I am trying to set the layout of a JFrame to be a grid bag layout. I want to to essentially look like 4 grids of equal size, but with the bottom 2 merged into one panel. I am adding JPanels to each. However, I get 3 small grids at the middle of the JFrame, not properly sized. It looks like this instead.
My code is as follows:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Hangman extends JPanel{
private String word;
private JPanel hA, gL, letters;
public void setupLayout(JFrame window){
window.setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
hA = new JPanel();
hA.setBackground(Color.blue);
c.fill = GridBagConstraints.BOTH;
c.gridx = 0;
c.gridy = 0;
window.add(hA, c);
gL = new JPanel();
gL.setBackground(Color.green);
c.fill = GridBagConstraints.BOTH;
c.gridx = 1;
c.gridy = 0;
window.add(gL, c);
letters = new JPanel();
letters.setBackground(Color.black);
c.fill = GridBagConstraints.BOTH;
c.weightx = 1.0;
c.gridx = 0;
c.gridy = 1;
c.gridwidth = 2;
window.add(letters, c);
}
public void startWindow(){
JFrame window = new JFrame();
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
int screenHeight = (int) screenSize.getHeight();
int windowHeight = (int) ((screenHeight / 4) * 3);
window.setSize(windowHeight, windowHeight);
window.setLocationRelativeTo(null);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setupLayout(window);
window.setVisible(true);
}
public void startGame(){
Prep prepare = new Prep();
word = prepare.findWord(true);
startWindow();
}
public static void main(String[] args){
Hangman start = new Hangman();
start.startGame();
}
}
It's not very important what Prep does. It just takes a random word from a text file. I couldn't see how it would affect the layout. To recap, I need to make it so each of the 4 grid spaces span one fourth of the window, and then make the bottom 2 cells merged with a JPanel added to each of them. Any help is appreciated. Thank you in advance.
EDIT:
I needed to set the weight of all of them to be 1. It is solved.
GridBagLayout displays each component at its preferred size. Since you didn't add any components to the panels you just see a small panel.
If you want the panels to fill the space available then you need to play with the constraints.
Read the section from the Swing tutorial on How to Use GridBagLayout for more information and working examples. You will want to look at the "fill" and "weightx/weighty" constraints.
and then make the bottom 2 cells merged
you will also need to look at the "gridwidth/gridheight" constraints.
I have created a simple for-loop that changes the amount of JTextFields and JLabels based on the value of a JSpinner, as seen in the following code:
public static ArrayList<ArrayList<JTextField>> ChangeQuestionAnswerFields(int numberOfQuestions){
ArrayList<ArrayList<JTextField>> txtFieldArray = new ArrayList<ArrayList<JTextField>>();
JPanel scrollPanel = new JPanel(new GridBagLayout());
//JScrollPane scrollPane = new JScrollPane(scrollPanel);
frame.add(scrollPanel, BorderLayout.CENTER);
GridBagConstraints c = new GridBagConstraints();
c.gridx = 0;
c.gridy = 0;
for(int i = 0; i != numberOfQuestions; i++){
JTextField tempQuestion = new JTextField(10);
JTextField tempAnswer = new JTextField(10);
JLabel tempQuestionHeader = new JLabel("Question " + (i + 1)+ " ");
JLabel tempQuestionLbl = new JLabel("Question: ");
JLabel tempAnswerLbl = new JLabel("Answer: ");
ArrayList<JTextField> tempArrayList = new ArrayList<>();
tempArrayList.add(tempQuestion);
tempArrayList.add(tempAnswer);
txtFieldArray.add(tempArrayList);
c.gridy++;
c.gridx = 0;
scrollPanel.add(tempQuestionHeader, c);
c.gridy++;
c.gridx = 0;
scrollPanel.add(tempQuestionLbl, c);
c.gridx = 1;
c.gridwidth = 3;
scrollPanel.add(tempQuestion, c);
c.gridy++;
c.gridx = 0;
scrollPanel.add(tempAnswerLbl, c);
c.gridx = 1;
c.gridwidth = 3;
scrollPanel.add(tempAnswer, c);
}
return txtFieldArray;
}
}
The value of the Spinner is passed into the method, and the method is called using a change listener (where noQuestions is the value of the JSpinner):
noQuestions.addChangeListener(e -> {
ChangeQuestionAnswerFields((int) noQuestions.getValue());
frame.revalidate();
frame.repaint();
});
This method is first called in the code when the screen first appears, and works properly. However, whenever the value of the spinner changes the original labels and fields stay on the screen and more text fields simply appear, or disappear on top.
http://i.imgur.com/GBY8L3u.png - JSpinner has a value of 2
http://i.imgur.com/pSQsA3G.png - JSpinner has a value of 3
Is there any way to fix this? Any help is much appreciated.
Thanks,
Tom
Minimal Runnable Example:
import javax.swing.*;
import java.awt.*;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.ArrayList;
public class MainGUI {
static JFrame frame = new JFrame("Math Reviser");
public static void main(String[] args) {
frame.setSize(400, 600);
frame.setVisible(true);
createScreen();
frame.revalidate();
frame.repaint();
public static void createScreen(){
frame.getContentPane().removeAll();
JSpinner noQuestions = new JSpinner(new SpinnerNumberModel(1, 1, 10, 1));
frame.add(noQuestions, BorderLayout.NORTH);
);
changeQuestionAnswerFields(1);
frame.revalidate();
frame.repaint();
noQuestions.addChangeListener(e -> {
changeQuestionAnswerFields((int) noQuestions.getValue());
frame.revalidate();
frame.repaint();
});
}
public static ArrayList<ArrayList<JTextField>> changeQuestionAnswerFields(int numberOfQuestions){
ArrayList<ArrayList<JTextField>> txtFieldArray = new ArrayList<ArrayList<JTextField>>();
JPanel scrollPanel = new JPanel(new GridBagLayout());
frame.add(scrollPanel, BorderLayout.CENTER);
GridBagConstraints c = new GridBagConstraints();
c.gridx = 0;
c.gridy = 0;
for(int i = 0; i != numberOfQuestions; i++){
JTextField tempQuestion = new JTextField(10);
JTextField tempAnswer = new JTextField(10);
JLabel tempQuestionHeader = new JLabel("Question " + (i + 1)+ " ");
JLabel tempQuestionLbl = new JLabel("Question: ");
JLabel tempAnswerLbl = new JLabel("Answer: ");
ArrayList<JTextField> tempArrayList = new ArrayList<>();
tempArrayList.add(tempQuestion);
tempArrayList.add(tempAnswer);
txtFieldArray.add(tempArrayList);
c.gridy++;
c.gridx = 0;
scrollPanel.add(tempQuestionHeader, c);
c.gridy++;
c.gridx = 0;
scrollPanel.add(tempQuestionLbl, c);
c.gridx = 1;
c.gridwidth = 3;
scrollPanel.add(tempQuestion, c);
c.gridy++;
c.gridx = 0;
scrollPanel.add(tempAnswerLbl, c);
c.gridx = 1;
c.gridwidth = 3;
scrollPanel.add(tempAnswer, c);
}
return txtFieldArray;
}
}
Using static variables and methods is an indication of a poorly designed application. There is no need for the static variables or methods. I suggest you read the section from the Swing tutorial on How to Use Labels. The LabelDemo.java code will show you how to create a panel containing all the components. This panel will then be added to the frame. This panel will also contain all the instance variables you need for your program.
Not only that the example will show you how to create the GUI components on the EDT which is something you should always do to prevent random errors since Swing was designed to be single threaded.
However, the main problem with your existing code is that you continue to create and add new panels to the content pane of the frame. Try changing the spinner to 2 and then resize the frame. Then try changing the spinner to 3 and resize the frame. After the resizing the first panel is displayed. This is because Swing will paint the last component added first so the first panel added will be painted on top of the last panel you created.
You can change this in your existing code by removing the old panel before adding the new panel:
static JFrame frame = new JFrame("Math Reviser");
static JPanel scrollPanel = new JPanel();
...
frame.remove(scrollPanel);
//JPanel scrollPanel = new JPanel(new GridBagLayout());
scrollPanel = new JPanel(new GridBagLayout());
However, I do not recommend this approach. As I initially suggestion you need to redesign the entire class. When you do the redesign I would use a BorderLayout on your panel and then you can add your spinner to the PAGE_START and then add a JScrollPane to the CENTER of the panel.
Then when you want to create a new panel you add the panel to the scrollpane using code like:
scrollPane.setViewportView( scrollPanel );
The scrollpane will refresh itself and you don't need to worry about revalidate() or repaint() or anything else.
I am trying to create a login page. I wrote code for two textboxes and one button. One textbox next to Username and other one next to Password. One "Sign In" button below. But I am not sure why the textbox's and button are not shown on my output. I only get the Username and password label's on my ouput screen.
Strange thing is whenever I stretch my output frame, (I mean either pulling the screen horizontally or vertically) the two textboxes and the button shows up.
Please check my code and let me know what's wrong. I was trying to put pictures to make easier to understand but I do not have enough reputation. Please help.
import javax.swing.*;
import java.awt.*;
public class HomeScreen{
public static void main(String args[]){
JFrame frame = new JFrame("Medical Store");
frame.setVisible(true);
frame.setSize(600,400);
JPanel panel = new JPanel(new GridBagLayout());
frame.getContentPane().add(panel, BorderLayout.NORTH);
GridBagConstraints c = new GridBagConstraints();
JLabel label1 = new JLabel("Username");
c.gridx = 0;
c.gridy = 0;
c.insets = new Insets(10,10,10,10);
panel.add(label1,c);
JLabel label2 = new JLabel("Password");
c.gridx = 0;
c.gridy = 1;
panel.add(label2,c);
JTextField textbox1 = new JTextField(10);
c.gridx = 1;
c.gridy = 1;
panel.add(textbox1,c);
JTextField textbox2 = new JTextField(10);
c.gridx = 2;
c.gridy = 1;
panel.add(textbox2,c);
JButton button1 = new JButton("Sign In");
c.gridx = 1;
c.gridy = 2;
panel.add(button1,c);
}
}
You're calling setVisible(true) before adding all components, and so your GUI is doing just that, drawing itself before components are added.
JFrame frame = new JFrame("Medical Store");
frame.setVisible(true);
// all components added here
Solution: make the setVisible(true) call at the end after adding all components.
JFrame frame = new JFrame("Medical Store");
// all components added here
frame.setVisible(true);
Now all components should be visualized.
Other quibbles:
Avoid calling setSize(...) on anything. Instead let the layout managers and component preferred sizes do that for you.
Call pack() on the JFrame just prior to setting it visible so that the above will happen.
I'm working on a JDialog (by hand, no GUI builders) and I'm having a problem doing the layout.
I have this:
My problem is that I don't know what how to tell that JList (within a JScrollPane) to have a Maximum width, I used the setSize, setMaximumSize and nothing works! I need that JList's width to be the half of the picture's size.
Explain the layouts:
The "Gene Information" is a GridLayout 2x4, it's contained by a JPanel with BoxLayout, the +/- JButtons is a BoxLayout also, all what I said before is within a BoxLayout.
Now, the "Genes" JPanel is a GridBagLayout.
What can I do?
Thanks in advance!
PD: The other borders are just for seeign the boundaries of the components.
Source Code:
scpGenesList.setViewportView(lstGenesList);
pnlGeneInfo.setLayout(new GridLayout(4, 2, 10, 10));
pnlGeneInfo.setBorder(BorderFactory.createCompoundBorder(
BorderFactory.createTitledBorder("Gene Information"),
BorderFactory.createEmptyBorder(10, 10, 10, 10)));
lblGeneSymbol.setText("Symbol:");
lblGeneSymbol.setHorizontalAlignment(SwingConstants.RIGHT);
lblGeneChromosome.setText("Chromosome:");
lblGeneChromosome.setHorizontalAlignment(SwingConstants.RIGHT);
lblGeneStartPosition.setText("Start Position:");
lblGeneStartPosition.setHorizontalAlignment(SwingConstants.RIGHT);
lblGeneStopPosition.setText("Stop Position:");
lblGeneStopPosition.setHorizontalAlignment(SwingConstants.RIGHT);
pnlGeneInfo.add(lblGeneSymbol);
pnlGeneInfo.add(lblGeneSymbolValue);
pnlGeneInfo.add(lblGeneChromosome);
pnlGeneInfo.add(lblGeneChromosomeValue);
pnlGeneInfo.add(lblGeneStartPosition);
pnlGeneInfo.add(lblGeneStartPositionValue);
pnlGeneInfo.add(lblGeneStopPosition);
pnlGeneInfo.add(lblGeneStopPositionValue);
pnlGWASAddRemoveButtons.setLayout(new BoxLayout(pnlGWASAddRemoveButtons, BoxLayout.X_AXIS));
pnlGWASAddRemoveButtons.add(Box.createHorizontalGlue());
pnlGWASAddRemoveButtons.add(cmdGenesAdd);
pnlGWASAddRemoveButtons.add(Box.createHorizontalStrut(10));
pnlGWASAddRemoveButtons.add(cmdGenesRemove);
pnlGWASAddRemoveButtons.add(Box.createHorizontalGlue());
pnlGeneInfoButtons.setLayout(new BoxLayout(pnlGeneInfoButtons, BoxLayout.Y_AXIS));
pnlGeneInfoButtons.add(pnlGeneInfo);
pnlGeneInfoButtons.add(Box.createVerticalStrut(10));
pnlGeneInfoButtons.add(pnlGWASAddRemoveButtons);
pnlGenesPanel.setLayout(new GridBagLayout());
pnlGenesPanel.setBorder(BorderFactory.createCompoundBorder(
BorderFactory.createTitledBorder("Genes"),
BorderFactory.createEmptyBorder(10, 10, 10, 10)));
GridBagConstraints ctrGenes = new GridBagConstraints();
ctrGenes.fill = GridBagConstraints.BOTH;
ctrGenes.gridx = 0;
ctrGenes.gridy = 0;
ctrGenes.gridwidth = 1;
ctrGenes.gridheight = 1;
ctrGenes.weighty = 1.0;
ctrGenes.weightx = 1.0;
ctrGenes.insets = new Insets(0, 0, 0, 10);
pnlGenesPanel.add(scpGenesList, ctrGenes);
GridBagConstraints ctrGenesInfoButton = new GridBagConstraints();
ctrGenesInfoButton.fill = GridBagConstraints.BOTH;
ctrGenesInfoButton.gridx = 1;
ctrGenesInfoButton.gridy = 0;
ctrGenesInfoButton.gridwidth = 1;
ctrGenesInfoButton.gridheight = 1;
ctrGenesInfoButton.weighty = 1.0;
ctrGenesInfoButton.weightx = 1.0;
pnlGenesPanel.add(pnlGeneInfoButtons, ctrGenesInfoButton);
contentPane.add(pnlGenesPanel);
pack();
Why not give the "Genes" panel a 2x1 GridLayout? That should ensure that both sides have the same size.
But actually, it would make more sense to me to give the list all space not taken by the controls, since those require a fixed amount of space while the list may benefit from all additional space it can get, if there are wide entries.
To that end, I would give the "Genes" panel a BorderLayout, put the list in the CENTER slot and the controls in the EAST slot.
Following #Michael Borgwardt's suggestion to let the list grow, you can use setVisibleRowCount() to produce a convenient initial panel size. If necessary, you can also examine the Dimension returned by getPreferredScrollableViewportSize(), which "computes the size of viewport needed to display visibleRowCount rows."
Without seeing all the code here it may be impossible to tell you what is wrong. One thing I would suggest if you have time is to take a look at MigLayout. You can use it with Swing & SWT and once you learn it is a pretty powerful layout manager IMHO.
Hope this helps, good luck.
It doesn't answer your question - but I've found that the JGoodies FormLayout to be more intuitive than the GridBagLayout. The library, as well as some examples, can be found here:
http://jgoodies.com/freeware/forms/index.html
I think the earlier solutions are all valid, and it is more of a coding preference in terms of which layout managers to use. Based on your requirement, here is a working one with standard layout managers only (Grid, GridBag and Border). Have fun, - MS.
import java.awt.;
import javax.swing.;
import javax.swing.border.*;
public class GeneDialog extends JDialog {
private String[] plusMinus = {"+","-"}, tfNames = {
"Symbol", "Chromosome", "Start position", "Stop position"},
listData = {"Gene01", "Gene02", "Gene03", "Gene04", "Gene05", "Gene06",
"Gene07", "Gene08", "Gene09", "Gene10", "Gene11", "Gene12"};
private JTextField[] gtField= new JTextField[tfNames.length];
private JList list = new JList (new DefaultListModel());
public GeneDialog (Frame f, String title) {
super (f, title, true);
Container cp = getContentPane();
cp.setLayout (new GridLayout(1,2));
JScrollPane listScrollPane = new JScrollPane (list);
listScrollPane.setBorder(BorderFactory.createCompoundBorder(
BorderFactory.createTitledBorder("Genes"),
BorderFactory.createEmptyBorder(10, 10, 10, 10)));
DefaultListModel lm = (DefaultListModel) list.getModel();
for (int k = 0 ; k < listData.length ; k++)
lm.addElement (listData[k]);
cp.add (listScrollPane);
cp.add (controlPanel());
pack();
}
private GridBagConstraints makeGBC (int inset) {
GridBagConstraints gbc = new GridBagConstraints();
gbc.insets = new Insets (inset, inset, inset, inset);
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 0;
gbc.gridy = GridBagConstraints.RELATIVE;
return gbc;
}
private JPanel controlPanel() {
JPanel cp = new JPanel (new BorderLayout()),
bp = new JPanel (new GridBagLayout()),
tp = new JPanel (new GridBagLayout());
GridBagConstraints gbc = makeGBC (10);
for (int i = 0 ; i < tfNames.length ; i++) {
JLabel label = new JLabel (tfNames[i], JLabel.TRAILING);
tp.add (label, gbc);
}
gbc.gridx++; gbc.weightx = 1.0f;
for (int i = 0 ; i < tfNames.length ; i++) {
gtField[i] = new JTextField(12);
tp.add (gtField[i], gbc);
}
gbc = makeGBC (10);
for (int i = 0 ; i < plusMinus.length ; i++) {
JButton b = new JButton (plusMinus[i]);
bp.add (b, gbc);
gbc.gridx++;
}
cp.add (tp, "Center");
cp.add (bp, "South");
return cp;
}
public static void main (String[] args) {
new GeneDialog (null, "Genes").setVisible (true);
}}
Try setting the maximum width for both the JScrollPane and the JList that is within it.
I just want to tell that I share the same opinion as javamonkey79. Take a look at MigLayout, you'll love it, and from Java 7 on it will be standart java-onboard layout.