I'm using a GridBagLayout Manager to define clearly where (for now) thow labels and a JScrollPane should be.
I use gridbagconstraint to tell the first JLabel named "label1" (with text) he should be 3 unit wide * 1 units tall.
I tell another JLabel named "blank" (empty) he should be 9 units wide * 1 unit tall.
Then I declare a JScrollPane, and tell it it should be on y=1, height = 11, and x=0 width = 12.
I set gridbag's contraint's fill to BOTH, because want each component to fill the rectangle I describe.
label1 should be a quarter of the whole width available, but since label1 has some text, label1 takes 2/3 of the space.
Is there a way to just ignore the PreferredSizes of the components, just like a GridLayout (kind of) does ?
I've read the documentation about this, but I don't find any clue.
Some source code :
public class JPanelMain {
//gridconstraints
private GridBagConstraints gbc;
private static final int min = 1;
private static final int maxSize= 12;
private static final int forth =maxSize/4;
private static final int third =maxSize/3;
public JPanelMain(JFrame frame) {
JPanel pane = new JPanel();
pane.setLayout(new GridBagLayout());
gbc = new GridBagConstraints(
0,//gridx
0,//gridy
0,//gridwidth
0,//gridheight
1,//weightx
1,//weighty
GridBagConstraints.CENTER,//anchor
GridBagConstraints.BOTH,//fill
new Insets(0,0,0,0),//insets
0,//padx
0//pady
);
JLabel label1 = new JLabel ();
label1.setBorder(BorderFactory.createTitledBorder("Label1"));
JLabel blank = new JLabel();
blank.setBorder(BorderFactory.createTitledBorder("blank"));
label1.setOpaque(true);
gbc.gridwidth =(third);
gbc.gridheight = (min);
pane.add(label1,gbc);
label1.setText("Label1");
blank.setOpaque(true);
gbc.gridx = third;
gbc.gridwidth = maxSize -third;
pane.add(blank,gbc);
gbc.gridy = min;
gbc.gridheight = maxSize - min;
gbc.gridx= 0;
gbc.gridwidth=maxSize;
DefaultListModel<String> patients = new DefaultListModel<>();
fill(patients);
JList<String> list = new JList<>(patients);
pane.add(new JScrollPane(list),gbc);
frame.add(pane);
}
private void fill (DefaultListModel<String> model) {
/**/
}
}
the result is as described (and it is the same in height):
I've read (and I believe mostly understood) the example.
There is no such concept as "units" in GridBagLayout. A GBL uses cells.
If you have two components on the first row then you have two cells. Each cell is sized by the component in the cell.
If you then have a component on the second row you have a couple of options. The component could be displayed in the first or second column. Or you could give the component a "gridwidth" of 2, which means it will fill the width of the two columns.
You could use the "weightx" constraint. It indicates how space should be allocated to a component when extra space is available. So if one component could be .20 and the other .80. This is the best way to assign space proportionally however this is only for the "extra" spaces. Each component will originally be sized at its preferred size.
If you want truly relative sizes then you can use the Relative Layout. It allows you to specify the size of components relative to the total space available, so the preferred size can be ignored.
So you would need to create a panel using the RelativeLayout for the first row containing the two labels and then add that panel to the panel using the GridBagLayout.
Related
i'm playing with GridBagLayout in java, I wrote the following code but it's not working as I expected
I expected that the first button would be placed in point (0,0) which is upper left of the frame.
secondly, I expected that the second button height and width would be twice the size of the first button height and width but they weren't.
here is the output: https://ibb.co/hDZPgx
here is the code:
import javax.swing.*;
import java.awt.*;
public class GUIJframe extends JFrame {
private JButton jb1 = new JButton("first");
private JButton jb2 = new JButton("second");
private JButton jb3 = new JButton("third");
private GridBagConstraints gbc = new GridBagConstraints();
private GridBagLayout gbl = new GridBagLayout();
public GUIJframe () {
jcb.addItem(names);
setLocation(150,150);
setSize(500,500);
setLayout(gbl);
addComponent(jb1,0,0,1,1);
addComponent(jb2,1,0,2,2);
addComponent(jb3,2,2,5,5);
setVisible(true);
}
public void addComponent (Component component, int gridx,int gridy, int width, int height) {
gbc.gridx = gridx;
gbc.gridy = gridy;
gbc.gridwidth = width;
gbc.gridheight = height;
gbl.setConstraints(component,gbc);
add (component);
}
}
I expected that the second button height and width would be twice the size of the first button height and width
Your expectation is wrong.
GridBagLayout cells are flexible. The width of one column does not depend on the width of other columns. It only depends on the widths of child components in it (and the insets and ipadx, if set).
If a component takes up two columns, but there is nothing else in either of those columns, there is no reason for the GridBagLayout to expand the columns any larger than necessary to accommodate the preferred width of that component.
The same is true for heights and GridBagLayout rows.
To force one component to be twice the size of another, you will need a different layout. SpringLayout can do it, though it’s not easy to use. You might find it easier to simply add a ComponentListener on the “smaller” component, and use that component’s new size as the basis for the ”larger” component‘s preferred size.
To achieve your desired result, I would use SpringLayout.
SpringLayout lets you create constraints, called Springs, which represent sizing ranges for edges, widths, and heights of components. These can depend on the size ranges of other components, or edges of the container.
SpringLayout layout = new SpringLayout();
setLayout(layout);
SpringLayout.Constraints jb1Constraints =
new SpringLayout.Constraints(jb1);
SpringLayout.Constraints jb2Constraints =
new SpringLayout.Constraints(
Spring.sum(jb1Constraints.getX(), jb1Constraints.getWidth()),
jb1Constraints.getY(),
Spring.scale(jb1Constraints.getWidth(), 2),
Spring.scale(jb1Constraints.getHeight(), 2));
SpringLayout.Constraints jb3Constraints =
new SpringLayout.Constraints(
Spring.sum(jb2Constraints.getX(),
Spring.scale(jb2Constraints.getWidth(), 0.5f)),
Spring.sum(jb2Constraints.getY(), jb2Constraints.getHeight()),
Spring.scale(jb1Constraints.getWidth(), 5),
Spring.scale(jb1Constraints.getHeight(), 5));
add(jb1, jb1Constraints);
add(jb2, jb2Constraints);
add(jb3, jb3Constraints);
// Make container big enough to hold all components.
layout.putConstraint(
SpringLayout.EAST, getContentPane(), 0,
SpringLayout.EAST, jb3);
layout.putConstraint(
SpringLayout.SOUTH, getContentPane(), 0,
SpringLayout.SOUTH, jb3);
The constraints for jb1 are the easiest: honor that component’s minimum size, prefered size, and maximum size. Location is (0, 0).
The constraints for jb2 depend on those of jb1:
The Spring for the x coordinate of jb2 is jb1.x + jb1.width, which is effectively the right edge of jb1.
jb2 has the same y as jb1 (which is, in fact, zero).
The width and height are those of jb1, scaled by 2.
The constraints for jb3 depend on both jb2 and jb1:
The x coordinate is jb2.x + (jb2.width ÷ 2), that is, the horizontal center point of jb2.
The y coordinate is jb2.y + jb2.height, which is effectively the bottom edge of jb2.
The width and height are those of jb1, scaled by 5.
Finally, SpringLayout is different from other layout managers, in that it doesn’t automatically set the size of the container it’s laying out to be big enough to hold all child components. We have to do that work ourselves, by using SpringLayout.putConstraint to link the container’s right edge (EAST) to the jb3’s right edge, and the container’s bottom edge (SOUTH) to jb3’s bottom edge.
I have a JScrollPane with a number of JLabel objects in a panel using a GridBagLayout. Each of the labels is displaying HTML text with rich elements which varies at run time.
I would like all labels to have the same width (driven by the width of the scroll pane) but vary in height depending on their content with the text wrapping (as is handled automatically by JLabel). If the labels exceed the scroll pane's height then a vertical scroll bar should appear.
Here is some sample code to demonstrate the problem:
public class ScrollLabels extends JFrame {
private final JPanel labelPanel = new JPanel(new GridBagLayout());
private final GridBagConstraints c = new GridBagConstraints();
public ScrollLabels() throws HeadlessException {
super("Scroll Labels");
}
public void createUI() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JScrollPane scroller = new JScrollPane(labelPanel);
add(scroller);
c.gridx = 0;
c.gridy = GridBagConstraints.RELATIVE;
c.fill = GridBagConstraints.HORIZONTAL;
addLabel("Here is <em>Rich Text</em>");
addLabel("Here is <ul><li>A</li><li>List</li></ul>");
addLabel("Here is <table><tr><th>A</th><th>Table></th></tr></table");
addLabel("Here is more <em>Rich Text</em>");
addLabel("Here is even more <b>Rich Text</b>");
addLabel("Here is a long sentence that should wrap when the panel "
+ "is too small for the text.");
pack();
}
private void addLabel(String text) {
JLabel label = new JLabel("<html>" + text + "</html>");
label.setBorder(BorderFactory.createEtchedBorder());
labelPanel.add(label, c);
}
public static void main(String[] args) {
ScrollLabels frame = new ScrollLabels();
frame.createUI();
frame.setVisible(true);
}
}
It correctly resizes the labels horizontally and shows scroll bars where appropriate. What it doesn't do is resize labels vertically to fit them within the scroll pane.
Here are the various things I have tried:
Changing the GridBagConstraint values. There are good controls for how to expand and contract components but I can't see any way to set a min or max width.
Setting the JScrollPane scroll bar policy to never show horizontal scroll bars. This just cuts off the label text rather than wrapping the text.
Manually setting the label size - i.e. setting the width from the scroll pane and the height depending on the text. I can't see an easy way to get the correct height of rich HTML text given a fixed width. In any case I'd prefer to have a layout manager that can do the job rather than manually coding preferred sizes.
The one thing I haven't tried yet is creating a custom layout manager. I suspect this might be the right answer but would like to see if any of you have an easier solution that I'm not seeing.
I would like all labels to have the same width (driven by the width of the scroll pane) but vary in height depending on their content
You need to implement the Scrollable interface on your panel and override the getScrollableTracksViewportWidth() method to return true. You will also need to provide default implementations for the other methods of the interface.
Or you can use the Scrollable Panel which provides method that allow you to set the scrolling properties.
I need to design a swing GUI which has a JFrame with a Menu on top and another main panel having three more panels in center and a separate panel in the bottom of the panel. The required design of the UI is as below
But when I run my swing application I get the output like this (all the panels are packed in the center of the window)
Below is my code
import java.awt.*;
import javax.swing.*;
public class FrontEndView {
private JFrame mainFrame;
private JPanel mainPanel,subPanelUp,subPanelDown,panelLeft,panelRight,panelCenter,panelDown;
private JScrollPane scrollPane;
private JList logViewList;
private JPanel panel1;
public FrontEndView(){
this.prepareGUI();
}
public void prepareGUI(){
mainFrame=new JFrame("GUI");
Toolkit tk = Toolkit.getDefaultToolkit();
int xSize = ((int) tk.getScreenSize().getWidth());
int ySize = ((int) tk.getScreenSize().getHeight());
mainFrame.setSize(xSize,ySize);
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setResizable(true);
mainFrame.setLayout(new BorderLayout());
mainPanel=new JPanel();
mainPanel.setLayout(new GridBagLayout());
mainPanel.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT);
GridBagConstraints gridbagConstMain = new GridBagConstraints();
GridBagConstraints gridbagConstSub = new GridBagConstraints();
subPanelUp=new JPanel();
subPanelUp.setLayout(new GridBagLayout());
subPanelUp.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT);
panelLeft=new JPanel();
panelLeft.setBorder(BorderFactory.createTitledBorder("Message Defs"));
gridbagConstSub.fill = GridBagConstraints.HORIZONTAL;
gridbagConstSub.weightx = 0.5;
gridbagConstSub.gridx = 0;
gridbagConstSub.gridy = 0;
subPanelUp.add(panelLeft, gridbagConstSub);
panelCenter=new JPanel();
panelCenter.setBorder(BorderFactory.createTitledBorder("Main Workspace"));
gridbagConstSub.fill = GridBagConstraints.HORIZONTAL;
gridbagConstSub.weightx = 0.5;
gridbagConstSub.gridx = 1;
gridbagConstSub.gridy = 0;
subPanelUp.add(panelCenter, gridbagConstSub);
panelRight=new JPanel();
panelRight.setBorder(BorderFactory.createTitledBorder("Script Viewer"));
gridbagConstSub.fill = GridBagConstraints.HORIZONTAL;
gridbagConstSub.weightx = 0.5;
gridbagConstSub.gridx = 2;
gridbagConstSub.gridy = 0;
subPanelUp.add(panelRight, gridbagConstSub);
mainPanel.add(subPanelUp,gridbagConstMain);
subPanelDown=new JPanel();
subPanelDown.setLayout(new BorderLayout());
panelDown=new JPanel();
panelDown.setBorder(BorderFactory.createTitledBorder("Log View"));
logViewList= new JList();
panelDown.add(logViewList);
gridbagConstSub.fill = GridBagConstraints.HORIZONTAL;
//gridbagConst.ipady=20;
//gridbagConst.weightx = 0.0;
gridbagConstSub.gridwidth = 5;
gridbagConstSub.gridx = 0;
gridbagConstSub.gridy = 0;
subPanelDown.add(panelDown,BorderLayout.PAGE_END);
mainPanel.add(subPanelDown, gridbagConstSub);
scrollPane=new JScrollPane(mainPanel,ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
mainFrame.add(scrollPane);
mainFrame.setVisible(true);
}
public static void main(String[] args){
FrontEndView frontEnd = new FrontEndView();
}
}
I want to fill the GridBagLayout's cells with the relevant panel/control it holds as shown in the design and also each panel should have its controls filled inside (I need to add a JList inside the panelDown whose size should be the size of the panelDown JPanel).Simply I don't need any extra space visible in my JFrame. Please guide me on what is missing in my code.
I would suggest you can use nested panels with different layout managers to solve the problem.
The default layout of a frame is a BorderLayout.
So you could create a panel and add it to the PAGE_END so it displays the entire width at the bottom.
Then you can create another panel that uses a GridLayout. You can then add 3 child panels to this panel and each panel can use its own layout. Then you add this panel to the CENTER of the frame. As the frame size changes the extra spaces will be allocated to the CENTER so the panels will dynamically grow.
Edit:
Too many panels for me to take the time to understand what is happening
I was suggesting a structure like this:
frame (which by default uses a BorderLayout)
--- CENTER
panel using GrigBagLayout
childPanel1
childPanel2
childPanel3
---- PAGE_END
JScrollPane containing the JList
When you create the JList the basic code would be:
JList list = new JList(...);
list.setVisibleRowCount(5);
JScrollPane scrollPane = new JScrollPane( list );
There is no need to create a panel just to add the list to another panel. The point of setting the visible row count is to give the JList a fixed height. Scrollbars will then appear in the scroll pane as needed.
Now that the PAGE_END has a fixed height component all the reset of the space will go to the component that you add to the CENTER of the frame.
all the panels are packed in the center of the window)
The panels are displayed at their preferred sizes when you use the GridBagLayout. If the total size of all the panels is less than the size of the scrollpane then they will be in the center. If you want the panels to fill the space available, then I believe you need to use the weightx/y constraints. Read the section from the Swing tutorial on How to Use GridBagLayout which describes all the constraints.
That is why I suggested a GridLayout instead. It will make all the panels the same size and will fill the viewport of the scroll pane without playing with constraints.
mainFrame.add(menubar,BorderLayout.NORTH);
That is not how you add a menubar to the frame.
You should be using:
mainFrame.setJMenuBar(menuBar);
You were told this in your last question. Why did you not listen to the advice??? Why should we take the time to help when you don't pay attention to what is suggested.
Based on your instructions I changed my design in a way all of the outer panels are used with Border Layout and the inner most ones with more controls were used with Grid, GridBag and FlowLayouts based on the requirement. In that way the entire design could be done nicely.
Also if a particular panel within a cell of a layout needs to be expanded, I used the setPreferredSize(new Dimension(int,int)) whenever required.
I'm trying to display two buttons next to a text field:
I gave up on the text already, but I really need the two buttons to remain small while the text field should expand with the window:
Currently, I use this layouts:
The text field and the two buttons are both in JPanel.
//JPanel group - the container
//List<JComponent> - the conponents added to JPanel
//int[] weights - weights of components
GridBagLayout lay = new GridBagLayout();
for(int i=0,l=fields.size(); i<l; i++) {
InputDef field = fields.get(i);
GridBagConstraints c = new GridBagConstraints();
if(weights.length<i) {
c.weightx = weights[i];
}
c.fill = GridBagConstraints.HORIZONTAL;
lay.setConstraints(field.getField(), c);
}
group.setLayout(lay);
In the documentation I see that for the components to fill their area horizontally, you should set the GridBagConstraints.HORIZONTAL to the constraints of the components.
Further, I read that you should set different GridBagConstraints#weightx to make the elements take different amount of space.
However running the code above doesn't do anything - the JPanel looks exactly the same with no layout manager whatsoever.
I'm writing a program that takes in some equations from the user. I want each constant to be entered in a JTextField, with each separated by a JTextArea (saying +x0, +x1, etc.). However, I can't quite get the formatting to work, and I'm not sure why. Here's the relevant code:
JTextField[][] dataTextFields = new JTextField[a+1][b+1];
JTextArea[][] dataLabels = new JTextArea[a][b+1];
for (int i = 0; i < a+1; i++)
{
for (int j = 0; j < b+1; j++)
{
dataTextFields[i][j] = new JTextField(10);
dataTextFields[i][j].setLocation(5+70*i, 10+30*j);
dataTextFields[i][j].setSize(40,35);
dataEntryPanel.add(dataTextFields[i][j]);
if (i < a)
{
String build = "x" + Integer.toString(i) + "+";
dataLabels[i][j] = new JTextArea(build);
dataLabels[i][j].setBackground(dataEntryPanel.getBackground());
dataLabels[i][j].setBounds(45+70*i,20+30*j,29,30);
dataEntryPanel.add(dataLabels[i][j]);
}
}
}
This creates JTextFields with JTextAreas 0f "+xi" in between them. However, when I run the applet, it looks like this:
I can click on the labels and bring them to the foreground, it seems, resulting in this:
I'd like for the labels to be visible without any effort from the user, obviously. Does JTextArea have some attribute that can be changed to bring this to the foreground? I'd really prefer not to add any more UI elements (panels, containers, etc). Thanks!
I would layout the container using GridBagLayout. GridBagLayout works a lot like HTML tables, where you have different cells, which grow in height and width to try and accommodate the content most effectively. For your particular layout, something like this would work:
public class SwingTest extends JFrame {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run () {
new SwingTest().setVisible(true);
}
});
}
public SwingTest () {
super("Swing Test");
JPanel contentPane = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridy = 0;
contentPane.add(createJTextField(), gbc.clone());
contentPane.add(new JLabel("x0+"), gbc.clone());
contentPane.add(createJTextField(), gbc.clone());
// go to next line
gbc.gridy++;
contentPane.add(createJTextField(), gbc.clone());
contentPane.add(new JLabel("x0+"), gbc.clone());
contentPane.add(createJTextField(), gbc.clone());
setContentPane(contentPane);
pack();
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
setLocationRelativeTo(null);
}
private JTextField createJTextField () {
JTextField textField = new JTextField(4);
textField.setMinimumSize(textField.getPreferredSize());
return textField;
}
}
GridBagLayout is the most complicated (but flexible) of the layouts, and requires many parameters to configure. There are simpler ones, like FlowLayout, BorderLayout, GridLayout, etc, that can be used in conjunction with one another to achieve complex layouts, as well.
In the Swing Tutorial, there is a very good section on Laying Out Components. If you plan on spending any significant amount of time on building Swing GUI's, it may be worth the read.
Note, that there is one strange caveat with GridBagLayout: if you are going to use a JTextField in a GridBagLayout, there is one silly issue (described here) that causes them to render at their minimum sizes if they can't be rendered at their preferred sizes (which causes them to show up as tiny slits). To overcome this, I specify the number of columns on my JTextField constructor so that the minimum is something reasonable, and then set the minimum size to the preferred size.