I am working on a Java desktop application. It uses MySQL database to store all data etc. I use swing for the GUI.
The GUI of this application is layed out as follows:
Main Window taking the entire screen size (with image in the
background)
Internal Window 800 x 600 centered within the Main
Window (that holds current content that can be switched between
using menu and/or event within the application.
LoginPanel.java:
import javax.swing.*;
import java.awt.*;
public class LoginPanel {
private JPanel loginPanel;
public void loginForm()
{
JButton loginSubmit = new JButton("Login");
loginPanel = new JPanel();
loginPanel.add(loginSubmit);
loginPanel.setSize(800, 600);
}
public JComponent getGUI()
{
return loginPanel;
}
public static void main(String[] args)
{
}
}
Main.java:
import javax.swing.*;
import java.awt.*;
public class Main {
public static void main(String[] args)
{
JFrame mainFrame;
mainFrame = new JFrame();
mainFrame.setLayout(new BorderLayout());
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setTitle("Caledonian Library System");
LoginPanel loginObj = new LoginPanel();
mainFrame.add(loginObj.getGUI());
mainFrame.pack();
mainFrame.setVisible(true);
}
}
Should I maybe use box layout? any suggestions?
Ok, I have just run a test program, and have achieved the result you are looking for. I have used a GridBagLayout which defaults to centre into the Container it is added to. It will not show up with the borders or other buttons built into a JFrame (though you can add a border if you wish later).
JFrame mainframe = new JFrame();
JPanel mainPanel = new JPanel();
GridBagLayout gridLayout = new GridBagLayout();
mainPanel.setLayout(gridLayout);
//GridBagConstraints allow you to set various features of the way the components appear
//in the grid. You can set this up as you wish, but defaults are fine for this example
GridBagConstraints gridConstraints = new GridBagConstraints();
//Just using FlowLayout as a test for now
JPanel centerPanel = new JPanel(new FlowLayout());
centerPanel.add(new JLabel("Hello"));
centerPanel.add(new JLabel("Centered"));
mainPanel.add(centerPanel, gridConstraints);
mainFrame.add(mainPanel);
If you found that the space around the side of your centered panel wasn't being used, and you wanted it to be use, you could try nesting mainPanel inside another panel that is using a BorderLayout, making sure that it is in BorderLayout.CENTER.
In the example I didn't bother changing GridBagConstraints from the default, as it was ok for this demonstration. However you can edit it as you wish, and then apply to each component you add to the GridBagLayout, making sure to include the GridBagConstraints object in each mainPanel.add(). Check the GridBagLayout tutorials for some good information.
Of course, if you would like more components in the centre other than the main window, you can then simply add them to the mainPanel (making sure to change the position in the GridLayout). There are going to be numerous ways of achieving what you want, but it really depends on what you feel looks good. The Layout Managers will do all of the resizing work for you.
Related
Well, actually I have a Layout problem in java Swing. I simply want to add a JPanel on the bottom of a Frame - a coding snipplet that might be done with every web based language in about 5 Minutes. Not so in Java. I tried to add a jPanel to a jFrame, that Contains a jContentPane, set the size of the jPanel to what I need and to repaint and revalidate the jFrame, as well as setting the LayOutManager to null.
Java shows me in this case a full-width jPanel, that fills my whole jFrame.
Therefore I tried another approach: I divided my jPanel in a fully transparent jPanel on top and a 20%opaque jPanel on the bottom. Still it didn't work out as expected.
Since then I tried to resize the child jPanels of my new Panel and the Panel as well and tried to repaint and revalidate the jFrame. Without any effect.
Despite of my efforts, java still shows me a full sized 20%opaque jPanel on the whole jFrame, that now contains another 20%opaque jPanel on Top.
I know that this whole problem is caused by the LayoutManager, Java useless per Default. However, it is not an option to set the LayoutManager to null or even change the LayoutManager of our jFrame, because that would lead us to refactor the whole functionality of our tiny app we worked on for several weeks.
public void showUndoPanel() {
System .out.println("Show Undo Panel");
JPanel myPanel = new JPanel(null);
JPanel glassPanel = new JPanel();
JPanel ContentPanel = new JPanel();
JLabel myJLabel = new JLabel("Great Job!");
myPanel.setBackground(new Color(255,122,122,100));
glassPanel.setSize(650, 550);
glassPanel.setBackground(new Color(255,122,122,100));
myPanel.add(glassPanel);
ContentPanel.setSize(650, 30);
ContentPanel.setBackground(new Color(255,122,122,20));
ContentPanel.add(myJLabel);
myPanel.revalidate();
myPanel.repaint();
undoPanel = myPanel;
myJFrame.add(undoPanel);
myJFrame.revalidate();
}
What I expected:
What it actually does:
Well, I solved the problem by using a BoxLayoutManager and a RigidArea. In case if anyone else may encounter that problem again in the future, I decided to provide the code for this simple solution.
public void showUndoPanel() {
System .out.println("Show Undo Panel");
JPanel myPanel = new JPanel(null);
JPanel glassPanel = new JPanel();
JPanel ContentPanel = new JPanel();
JLabel myJLabel = new JLabel("Great Job!");
myPanel.setBackground(new Color(255,255,255,0));
myPanel.setLayout(new BoxLayout(myPanel, BoxLayout.PAGE_AXIS));
glassPanel.setSize(650, 650);
glassPanel.setBounds(0,0,650,550);
glassPanel.setBackground(new Color(255,122,122,0));
myPanel.add(glassPanel);
myPanel.add(Box.createRigidArea(new Dimension(0,450)));
ContentPanel.setSize(650, 30);
ContentPanel.setBounds(0,750,650,30);
ContentPanel.setBackground(new Color(255,122,122,20));
ContentPanel.add(myJLabel);
myPanel.add(ContentPanel);
myPanel.revalidate();
myPanel.repaint();
undoPanel = myPanel;
myJFrame.add(undoPanel);
myJFrame.revalidate();
}
Now it behaves as expected:
BorderLyout would make it easier to implement.
Note the comments in the following mre:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Main {
private static JFrame myJFrame;
public static void main(String[] args) {
myJFrame = new JFrame();
myJFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
myJFrame.setLocationRelativeTo(null);
showUndoPanel();
myJFrame.pack();
myJFrame.setVisible(true);
}
public static void showUndoPanel() {
JPanel myPanel = new JPanel();
myPanel.setBackground(new Color(255,255,255,0));
myPanel.setLayout(new BorderLayout());
JPanel glassPanel = new JPanel(); //uses FlowLayout by default
//glassPanel.setSize(650, 650); //use preferred size
glassPanel.setPreferredSize(new Dimension(650, 650));
//glassPanel.setBounds(0,0,650,550); //no need to set bounds. bounds are set by the layout manager
glassPanel.setBackground(new Color(255,122,122,0));
myPanel.add(glassPanel, BorderLayout.CENTER);
JPanel contentPanel = new JPanel(); //uses FlowLayout by default
//contentPanel.setSize(650, 30);//use preferred size
contentPanel.setPreferredSize(new Dimension(650, 30));
//contentPanel.setBounds(0,750,650,30); //no need to set bounds. bounds are set by the layout manager
contentPanel.setBackground(new Color(255,122,122,20));
JLabel myJLabel = new JLabel("Great Job!");
contentPanel.add(myJLabel);
myPanel.add(contentPanel, BorderLayout.SOUTH);
myJFrame.add(myPanel);
}
}
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)
The useless Layout Manager guy is back again, I just can't seem to get my head around these darn layouts and make them work the way I want.
Anyway, I want to have a JFrame which has one large panel at the top (I call it a header) which runs from the left to right side of the frame at the north part of the frame, then four panels below it, two just below the header and two below those, and finally a "footer" panel, basically the same as the header panel, only at the south part of the frame.
Like this:
I had code which had the four middle panels working fine, but the header panel just messed everything up, and I have since been testing with the demo layout manager code for GridBagLayout, GridLayout again and BoxLayout. I can't getting any to work as I want.
For the aware of you here, you will probably notice I've already had a question related to this, and if having two similar questions are not allowed, please make me aware and I will move this to my previous question and this can be closed.
public Shop() {
shopUI = new JFrame("Shop Menu");
shopUI.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
shopUI.setBounds(100, 100, 700, 500);
shopUI.setResizable(false);
allPanels = new JPanel();
headerPanel = new JPanel();
headerPanel.setLayout(new BorderLayout());
headerPanel.setBackground(Color.cyan);
mainPanel = new JPanel();
mainPanel.setLayout(new GridLayout(2,2));
topLeft = new JPanel();
topLeft.setBackground(Color.pink);
topRight = new JPanel();
topRight.setBackground(Color.black);
bottomLeft = new JPanel();
bottomLeft.setBackground(Color.green);
bottomRight = new JPanel();
bottomRight.setBackground(Color.blue);
footerPanel = new JPanel();
footerPanel.setLayout(new BorderLayout());
footerPanel.setBackground(Color.magenta);
mainPanel.add(topLeft);
mainPanel.add(topRight);
mainPanel.add(bottomLeft);
mainPanel.add(bottomRight);
allPanels.add(headerPanel, BorderLayout.NORTH);
allPanels.add(footerPanel, BorderLayout.SOUTH);
allPanels.add(mainPanel);
shopUI.add(allPanels);
shopUI.setVisible(true);
}
I suggest learning about border layout.
for what you want, put the header in the NORTH of the border panel, and the footer in the SOUTH. How you do your other panels depends a bit on what you want them to do; if you always want them to be the same size as each other, you can use a gridlayout for them; if not, you can use boxlayout to lay either the two pairs horizontally or the two pairs vertically, again depending on what you want them to do when the frame resizes.
I think using layout managers is simplified by deciding what you want to happen in the first place, including what happens when the frame is resized. That's a large part of what layouts are all about, anyway -- what stretches, what lines up, etc.
Anyway. what you have there looks like classic BorderLayout to me. Let us know if you need further help. Incidentally, BorderLayout is default for JFrame...
edit...
this will get more interesting when you put something in the panels...
package simpleborderlayout;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main
{
public static void main(String[] args)
{
Main main = new Main(args);
main.go();
}
public Main(String ... args)
{}
public void go()
{
JPanel headerPanel = getPanel(Color.RED);
JPanel footerPanel = getPanel(Color.BLUE);
JPanel p1 = getPanel(Color.GRAY);
JPanel p2 = getPanel(Color.GRAY);
JPanel p3 = getPanel(Color.GRAY);
JPanel p4 = getPanel(Color.GRAY);
GridLayout gridLayout = new GridLayout(2,2);
JPanel middlePanel = new JPanel(gridLayout);
middlePanel.add(p1);
middlePanel.add(p2);
middlePanel.add(p3);
middlePanel.add(p4);
JFrame mainFrame = new JFrame();
mainFrame.add(headerPanel, BorderLayout.NORTH);
mainFrame.add(middlePanel, BorderLayout.CENTER);
mainFrame.add(footerPanel, BorderLayout.SOUTH);
mainFrame.pack();
mainFrame.setVisible(true);
}
private JPanel getPanel(Color c)
{
JPanel result = new JPanel();
result.setBorder(BorderFactory.createLineBorder(c));
return result;
}
}
So I would like to have three JButtons all on top of each other, but not to large in width or height either. I am not too familiar with Java's layouts, and to be honest I am not too keen on them. Please view the image a code below to explain to me how, thanks.
package com.aqagame.harrykitchener;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
public class Main
{
private JButton playGame, playerNames, exitGame;
public Main()
{
JPanel mainCard = new JPanel(new BorderLayout(8, 8));
playGame = new JButton("Play Game");
playerNames = new JButton("Player Names");
exitGame = new JButton("Exit Game");
mainCard.add(playGame, BorderLayout.NORTH);
mainCard.add(playerNames, BorderLayout.CENTER);
mainCard.add(exitGame, BorderLayout.SOUTH);
JFrame window = new JFrame("Harry's AQA game");
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.getContentPane().add(mainCard);
window.setSize(900, 800);
window.setLocationRelativeTo(null);
window.setVisible(true);
}
public static void main(String args[])
{
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Main();
}
});
}
}
Check out the Java Documentation for the different layout managers. I know you're not familiar with them, which is why you should probably start. Once you get used to them there is no end to their benefits. There is a lot of excellent information in the documentation and I am sure you will learn a lot. Personally, I recommend looking at the Box Layout:
Create JPanel that uses a GridLayout and add all the buttons to the panel. The GridLayout will automactially size the buttons to be the same size.
Set the layout manager of your main window to use a GridBagLayout.
add the panel to the main window using the default GridBagConststraints. Then the panel will automatically be centered both horizontally and vertically.
To not use Box or GridBag, I think a combination such as this may work out:
Have main panel (let's call it A) have a BorderLayout
Create another panel (let's call it B), with a FlowLayout, with constructor aligning components to the center
Create another panel (let's call it C), with a GridLayout, 1 column 3 rows
Add each button to a new JPanel with a FlowLayout (1 JPanel per button, so buttons are wrapped by a FlowLayout), and then add each of those JPanels to C
Add C to B
Add B to A (center position)
I think this should cause buttons to be on top of each other with small amount of padding while not being stretched widthwise and while appearing in the center of the screen.
(Say) I've created a JPanel with three buttons. I want to place the buttons as follows (I've done this using netbeans GUI editor. But I need to write the whole GUI manually).
Can some one show me a way to achieve this.
(In words, I need to place some buttons right aligned, some other left aligned.)
I guess you want the Configure button to be as far to the left as possible, and the ok and cancel grouped together to the right. If so, I would suggest using a BorderLayout and place the Configure button in WEST, and a flow-layout for Ok, Cancel and place that panel in the EAST.
Another option would be to use GridBagLayout and make use of the GridBagConstrant.anchor attribute.
Since you're taking the time to avoid the NetBeans GUI editor, here's a nice example for you :-)
Code below:
import java.awt.BorderLayout;
import javax.swing.*;
public class FrameTestBase {
public static void main(String args[]) {
// Will be left-aligned.
JPanel configurePanel = new JPanel();
configurePanel.add(new JButton("Configure"));
// Will be right-aligned.
JPanel okCancelPanel = new JPanel();
okCancelPanel.add(new JButton("Ok"));
okCancelPanel.add(new JButton("Cancel"));
// The full panel.
JPanel buttonPanel = new JPanel(new BorderLayout());
buttonPanel.add(configurePanel, BorderLayout.WEST);
buttonPanel.add(okCancelPanel, BorderLayout.EAST);
// Show it.
JFrame t = new JFrame("Button Layout Demo");
t.setContentPane(buttonPanel);
t.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
t.setSize(400, 65);
t.setVisible(true);
}
}