I'm using the NetBeans GUI builder to handle my layout (I'm terrible with LayoutManagers) and am trying to place a simple JLabel so that it is always centered (horizontally) inside its parent JPanel. Ideally, this would maintain true even if the JPanel was resized, but if that's a crazy amount of coding than it is sufficient to just be centered when the JPanel is first created.
I'm bad enough trying to handle layouts myself, but since the NetBeans GUI Builder autogenerates immutable code, it's been impossible for me to figure out how to do this centering, and I haven't been able to find anything online to help me.
Thanks to anybody who can steer me in the right direction!
Here are four ways to center a component:
import java.awt.*;
import javax.swing.*;
import javax.swing.border.*;
class CenterComponent {
public static JLabel getLabel(String text) {
return getLabel(text, SwingConstants.LEFT);
}
public static JLabel getLabel(String text, int alignment) {
JLabel l = new JLabel(text, alignment);
l.setBorder(new LineBorder(Color.RED, 2));
return l;
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
JPanel p = new JPanel(new GridLayout(2,2,4,4));
p.setBackground(Color.black);
p.setBorder(new EmptyBorder(4,4,4,4));
JPanel border = new JPanel(new BorderLayout());
border.add(getLabel(
"Border", SwingConstants.CENTER), BorderLayout.CENTER);
p.add(border);
JPanel gridbag = new JPanel(new GridBagLayout());
gridbag.add(getLabel("GridBag"));
p.add(gridbag);
JPanel grid = new JPanel(new GridLayout());
grid.add(getLabel("Grid", SwingConstants.CENTER));
p.add(grid);
// from #0verbose
JPanel box = new JPanel();
box.setLayout(new BoxLayout(box, BoxLayout.X_AXIS ));
box.add(Box.createHorizontalGlue());
box.add(getLabel("Box"));
box.add(Box.createHorizontalGlue());
p.add(box);
JFrame f = new JFrame("Streeeetch me..");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setContentPane(p);
f.pack();
f.setLocationByPlatform(true);
f.setVisible(true);
}
});
}
}
By using Borderlayout, you can put any of JComponents to the CENTER area. For an example, see an answer to Stack Overflow question Get rid of the gap between JPanels. This should work.
Even with BoxLayout you can achieve that:
JPanel listPane = new JPanel();
listPane.setLayout(new BoxLayout(listPane, BoxLayout.X_AXIS ));
JLabel label = new JLabel();
listPane.add(Box.createHorizontalGlue());
listPane.add(label);
listPane.add(Box.createHorizontalGlue());
mKorbel's solution is perfect for your goal. Anyway I always like to suggest BoxLayout because it's very flexible.
Mara: "thanks for your response, however the NetBeans GUI Build uses GroupLayout and this is not overridable."
Not true! Right click anywhere inside JFrame (or any other GUI container) in NetBeans GUI builder and select "Set Layout". By default is selected "Free Design", which is Group layout, but you can select any other layout including Border layout as advised by mKorbel.
There's many ways to do this, depending on the layout manager(s) you use. I suggest you read the Laying Out Components Within a Container tutorial.
I believe the following will work, regardless of layout manager:
JLabel.setHorizontalAlignment(SwingConstants.CENTER)
Related
I'm trying to put a JPanel inside OR on a JPanel, whichever may be the case, ultimately I just want this to work like this
As you can see on the picture, the red line is a JFrame and it has 2 JPanels inside it, on the green JPanel there are some different JPanels.
I need help with the green JPanel and the little JPanels inside it. Is there any way to make it work like this?
Any help would be greatly appreciated!
==============EDIT 1==============
So here is some code, to show you what I've done so far with the help of #hfontanez.
import javax.swing.*;
import java.awt.*;
import java.io.IOException;
public class Main
{
public static void main(String[] args)
{
//JFrame
JFrame jframe = new JFrame();
jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jframe.setSize(1920, 1080);
jframe.setResizable(false);
jframe.setLocationRelativeTo(null);
jframe.setVisible(true);
//parentJpanel - This is the main panel
JPanel parentJpanel = new JPanel();
parentJpanel.setBackground(Color.YELLOW);
parentJpanel.setSize(1920, 1080);
parentJpanel.setLayout(new BorderLayout());
//smallPanel - This is the little panel on the bottom
JPanel smallPanel = new JPanel();
smallPanel.setBackground(Color.GREEN);
smallPanel.setSize(1920, 300);
smallPanel.setLocation(0, 780);
smallPanel.setLayout(new BoxLayout(smallPanel, BoxLayout.PAGE_AXIS));
parentJpanel.add(smallPanel);
jframe.add(parentJpanel);
}
}
I expected the top part to be yellow, and the small part on the bottom to be green, yet the whoel thing turned green. What did I do wrong?
The pictured GUI is created using three panels.
The YELLOW panel is the game play area. It has no layout, no components (which define their own preferred sizes) and is custom painted, so it defines a sensible preferred size to report to the layout manager.
The GREEN panel contains controls. It uses a FlowLayout.
The RED panel uses a BorderLayout, and puts the YELLOW panel in the CENTER and the GREEN panel in the PAGE_END.
Code
This is the code that made the screenshot seen above.
import javax.swing.*;
import javax.swing.border.EmptyBorder;
import java.awt.*;
public class GameLayout {
GameLayout() {
// The main GUI. Everything else is added to this panel
JPanel gui = new JPanel(new BorderLayout(5, 5));
gui.setBorder(new EmptyBorder(4, 4, 4, 4));
gui.setBackground(Color.RED);
// The custom painted area - it is a panel that defines its preferred size.
gui.add(new GamePanel());
JPanel buttonPanel = new JPanel(new FlowLayout(FlowLayout.LEADING));
buttonPanel.setBackground(Color.GREEN);
for (int ii = 1; ii<5; ii++) {
buttonPanel.add(new JButton("B " + ii));
}
gui.add(buttonPanel,BorderLayout.PAGE_END);
JFrame f = new JFrame("Game Layout");
f.setContentPane(gui);
f.setLocationByPlatform(true);
f.pack();
f.setVisible(true);
}
public static void main(String[] args) {
Runnable r = () -> new GameLayout();
SwingUtilities.invokeLater(r);
}
}
class GamePanel extends JPanel {
GamePanel() {
setBackground(Color.YELLOW);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 100);
}
}
You need to use a LayoutManager so when you put the JPanel inside the other JPanel it will have the correct look. If you simply put panels inside the others, the parent JPanel will use its default layout manager, which is FlowLayout.
For the look of it, it seems you need to use Border Layout for the parent (yellow) panel. For the green, you have options, but I think your best bet is to use Box Layout with a PAGE_AXIS Component Orientation.
In general, you need to be familiarized with two things: 1) Layout Managers and how they behave, and 2) the default layout behavior of JComponents.
I currently have a Jframe that I want to add to a tab instead.
(I used a frame just for testing purposes, to make sure the look and feel is correct, but when trying to add it to a JTabbedPane, the frame starts to look blue (weird top aswell).
I tried copying my settings from my original frame to the new frame but that did not help.
JTabbedPane tabs = new JTabbedPane();
tabs.addTab("1", frame.getContentPane());
JFrame FinalFrame = new JFrame();
FinalFrame.setDefaultLookAndFeelDecorated(true);
FinalFrame.setSize(WIDTH, HEIGTH);
FinalFrame.setLocation(100, 150);
FinalFrame.setTitle("Primal-Pvm Notification center");
FinalFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
FinalFrame.add(tabs);
Side by side view of the problem and the frame before adding it to the tab:
Edit: Answer by George Z. helped me out a lot.
Like he said to solve the problem:
Don't add things to your main frame but add them to a Jpanel and add that to a JTabbedPane.
If you have a Jpanel that you are adding to a tab that contains an override in the paintComponent, you have to create that class as the Jpanel so:
JPanel panel = new LineDrawer([Enter parameters]);
panel.setLayout([Enter Layout]);
The way you are approaching this seems to be pretty complex hence this weird behavior. (Looks like a look and feel problem? - show the part of the code that sets it)
However, I suggest you to create only one JFrame (this question explains why you should do that), set the layout of its content pane to BorderLayout and keep it like this. Its a rare situation to mess up with content panes. After that create independent JPanels representing the tab(s) you would like to have. Finally create a JTabbedPane with these panels and add it to the content frame of the JFrame.
A small example would be:
public class TabbedPanelExample extends JFrame {
public TabbedPanelExample() {
super("test");
setDefaultCloseOperation(EXIT_ON_CLOSE);
setLayout(new BorderLayout());
JTabbedPane pane = new JTabbedPane();
pane.addTab("FirstTab", createFirstTab());
pane.addTab("SecondTab", createSecondTab());
add(pane);
setSize(400, 400);
setLocationRelativeTo(null);
}
private Component createFirstTab() {
JPanel panel = new JPanel(new FlowLayout());
panel.add(new JLabel("Some Component"));
panel.add(new JTextField("Some Other Component"));
return panel;
}
private Component createSecondTab() {
JPanel panel = new JPanel(new FlowLayout());
panel.add(new JLabel("Some Component"));
panel.add(new JButton("Some Other Component"));
return panel;
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
new TabbedPanelExample().setVisible(true);
});
}
}
Post edit based on this comment:
Well I do have a Jframe with a lot of elements added to it so it kinda
is a hassle to switch it all to panels;
A JFrame cannot have a lot of elements. You take a look on how to use root panes. The container that "has a lot of elements" of a JFrame is its rootpane which is mostly completed by its contentpane. When you frame.add(component), you add the component to its content pane. Guess what? A JFrame's content pane is a JPanel. So are a already to panels.
Now in order to make this work, try to do as i said and frame.setLayout(new BorderLayout(); //changes layout to contentpane. Assuming you have a bunch of components (lets say comp1,comp2) and you are adding them like:
frame.add(comp1);
frame.add(comp2);
You must do the following in order to make it clear. Create a JPanel and instead of frame.add(comp1), do panel.add(comp1). So this JPanel has all the components you added in JFrame. After that create your JTabbedPane:
JTabbedPane pane = new JTabbedPane();
pane.addTab("tab", panel);
and finally add this pane to the content pane of your JFrame:
frame.add(pane);
In conclusion, you will move all the components you have added to your frame into a JPanel, add this JPanel to a JTabbedPane, and finally add this JTabbedPane to the frame (contentpane). Frame has only one component.
So I have this JFrame that contains a JPanel and in there I add JLabels with information I want but since I'll be adding labels all the time at some point the text is too long to appear so I want to add a scrollbar. Basically I want to make my JFrame with a JPanel in it scrollable. I have this code but my problem is that even though the scrollbar appears but it doesnt move and doesn't really work when the text is a lot, meaning the text still gets cut out and the scrollbar is there not moving. Does anyone know how to fix this?
import javax.swing.*;
import java.awt.*;
import java.util.*;
public class Bar {
JFrame info = new JFrame("Information");
JLabel ballinf = new JLabel();
JPanel contentPane = new JPanel();
JScrollPane scrolling = new JScrollPane();
public Bar(){
contentPane.setOpaque(true);
contentPane.setBackground(Color.WHITE);
contentPane.setLayout(null);
scrolling = new JScrollPane(contentPane,JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
info.add(scrolling);
info.setSize(750, 600);
info.setLocationByPlatform(true);
info.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
info.setVisible(true);
}
public void adding(int pos){
ballinf = new JLabel("Something ",JLabel.CENTER);//assume the text will be bigger here and have more info
ballinf.setSize(700, 30);
ballinf.setForeground(Color.green);
ballinf.setLocation(5, 5+pos);
contentPane.add(ballinf);
info.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
info.setVisible(true);
}
public static void main(String[] args){
Bar stats = new Bar();
stats.adding(0);
stats.adding(20);//this will be done in a for loop for more than 2 times so the text ends up to be a lot
}
}
contentPane.setLayout(null);
Don't use a null layout!!!
You need to use an appropriate layout manager. Read the section from the Swing tutorial on Layout Managers for more information and working examples. The layout manager will then determine the preferred size of the panel as you add components to the panel.
The scrollpane will then display the scrollbars when necessary.
If you dynamically add components to the panel (after the GUI is visible) then the code should be something like:
panel.add(...);
panel.revalidate();
panel.repaint();
Here's the portion of my java application GUI that I have a question about.
What this GUI consists is a blue JPanel(container) with default FlowLayout as LayoutManager that contains a Box which contains two JPanels(to remove the horizontal spacing or i could have used setHgaps to zero for that matter instead of a Box) that each contains a JLabel.
Here's my code for creating that part of the GUI.
private void setupSouth() {
final JPanel southPanel = new JPanel();
southPanel.setBackground(Color.BLUE);
final JPanel innerPanel1 = new JPanel();
innerPanel1.setBackground(Color.ORANGE);
innerPanel1.setPreferredSize(new Dimension(DEFAULT_WIDTH, DEFAULT_HEIGHT));
innerPanel1.add(new JLabel("Good"));
final JPanel innerPanel2 = new JPanel();
innerPanel2.setBackground(Color.RED);
innerPanel2.setPreferredSize(new Dimension(DEFAULT_WIDTH, DEFAULT_HEIGHT));
innerPanel2.add(new JLabel("Luck!"));
final Box southBox = new Box(BoxLayout.LINE_AXIS);
southBox.add(innerPanel1);
southBox.add(innerPanel2);
myFrame.add(southPanel, BorderLayout.SOUTH);
}
My question is how would i get rid the vertical padding between the outer JPanel(the blue one) and the Box?
I know this is padding because i read on Difference between margin and padding? that "padding = space around (inside) the element from text to border."
This wouldn't work because this has to due with gaps(space) between components.- How to remove JPanel padding in MigLayout?
I tried this but it didn't work either. JPanel Padding in Java
You can just set the gaps in the FlowLayout, i.e.
FlowLayout layout = (FlowLayout)southPanel.getLayout();
layout.setVgap(0);
The default FlowLayout has a 5-unit horizontal and vertical gap. Horizontal doesn't matter in this case as the BorderLayout is stretching the panel horizontally.
Or simple initialize the panel with a new FlowLayout. It'll be the same result.
new JPanel(new FlowLayout(FlowLayout.CENTER, 0, 0));
Edit:
"I tried that, didn't work.."
Works for me...
Setting the gap ↑ Not setting the gap ↑
import java.awt.*;
import javax.swing.*;
public class Test {
public void init() {
final JPanel southPanel = new JPanel();
FlowLayout layout = (FlowLayout)southPanel.getLayout();
layout.setVgap(0);
southPanel.setBackground(Color.BLUE);
final JPanel innerPanel1 = new JPanel();
innerPanel1.setBackground(Color.ORANGE);
innerPanel1.add(new JLabel("Good"));
final JPanel innerPanel2 = new JPanel();
innerPanel2.setBackground(Color.RED);
innerPanel2.add(new JLabel("Luck!"));
final Box southBox = new Box(BoxLayout.LINE_AXIS);
southBox.add(innerPanel1);
southBox.add(innerPanel2);
southPanel.add(southBox); // <=== You're also missing this
JFrame myFrame = new JFrame();
JPanel center = new JPanel();
center.setBackground(Color.yellow);
myFrame.add(center);
myFrame.add(southPanel, BorderLayout.SOUTH);
myFrame.setSize(150, 100);
myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
myFrame.setLocationByPlatform(true);
myFrame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable(){
public void run() {
new Test().init();
}
});
}
}
Note: Always post a runnable example (as I have done) for better help. You say it doesn't work, but it always works for me, so how would we know what you're doing wrong without some code that will run and demonstrate the problem?
So I have a slight issue with adding two JPanels to a main main panel. I've put it as a quick example of what I want to do since you don't want to be looking through loads of lines of unnecessary code :). I want panel one to be added first (north) and then panel two (south). I've tried using Border layout and positioning them invoking north and south on BorderLayout when adding the panels but still no luck.
Thanks in advance.
private JPanel one,two;
public Example(){
one = new JPanel();
one.setSize(new Dimension(400,400));
two = new JPanel(new GridLayout(7,8));
two.setSize(new Dimension(400,400));
one.setBackground(Color.BLACK);
two.setBackground(Color.BLUE);
JPanel mainpanel = new JPanel();
mainpanel.setBackground(Color.orange);
mainpanel.add(one);
mainpanel.add(two);
add(mainpanel);
setSize(500,500);
setVisible(true);
}
If you want to use BorderLayout, then BorderLayout.CENTER takes up as much space as it can, and the other directions take only what they need. If you add extra stuff to the JPanels, they will get bigger, based on the needs of the objects they contain.
If you want to just divide the space evenly within the main JPanel, try this:
JPanel mainpanel = new JPanel(new GridLayout(2, 1));
That creates a GridLayout with 2 rows and 1 column...
Try this code. There was issue that apparently if you install grid layout on a panel and you add no components it will not take space.
import java.awt.BorderLayout;
import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Example extends JFrame
{
private JPanel one, two;
public Example()
{
one = new JPanel();
two = new JPanel();///new GridLayout(7, 8));
one.setBackground(Color.BLACK);
two.setBackground(Color.BLUE);
JPanel mainpanel = new JPanel(new BorderLayout());
mainpanel.setBackground(Color.orange);
mainpanel.add(one, BorderLayout.NORTH);
mainpanel.add(two, BorderLayout.SOUTH);
setContentPane(mainpanel);
setSize(500, 500);
setVisible(true);
}
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
#Override
public void run()
{
Example f = new Example();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
});
}
}
GridLayout ignores the values set in setSize method of contained components. If you want to control the size of each component, consider using GridBagLayout.