I wrote this code sample to illustrate a problem I'm having with my program.
I expect to be able to slide the JSplitPane's slider bar to the left, beyond the edge of the buttons, compressing that JPanel, and have the FlowLayout wrap the buttons to a second row.
Instead, the JSplitPane does not allow me to move the slider past the rightmost button on the screen, and if I resize the entire JFrame to force the compression, the buttons (I presume) are just running off the righthand side of the JPanel, underneath the slider bar (I guess, because I obviously cannot see them).
What am I doing wrong?
import java.awt.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
public class Driver implements Runnable {
public static void main(String[] args) {
(new Driver()).run();
}
public void run() {
try {
go();
} catch (Exception e) {
e.printStackTrace();
System.exit(-1);
}
}
private void go() throws Exception {
JFrame jframe = new JFrame("FlowLayoutTest");
JPanel left = new JPanel();
left.setBackground(Color.RED);
left.setLayout(new BorderLayout());
JPanel right = new JPanel();
right.setBackground(Color.BLUE);
right.setLayout(new BorderLayout());
JSplitPane topmost =
new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, left, right);
jframe.setContentPane(topmost);
JPanel bottomleft = new JPanel();
bottomleft.setBackground(Color.GREEN);
bottomleft.setLayout(new FlowLayout());
left.add(bottomleft, BorderLayout.PAGE_END);
for (int i = 0; i < 10; i++) {
bottomleft.add(new JButton("" + i));
}
jframe.pack();
jframe.setVisible(true);
jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
Is there another layout manager besides FlowLayout that will do what I'm looking for?
Wrap Layout should work.
If you add this
bottomleft.setMinimumSize(new Dimension(0, 0));
before the pack() then it'll reflow. BUT, it won't re-pack the border layout, so instead of two lines you'll get one with the rest cut off. So after a resize you'll have to repack the border layout. If you omit the border layout then it'll reflow like you want.
That said, you should avoid FlowLayout like the plague. Most of the layouts that come with Swing are poor, but FlowLayout is one of the worst offenders.
Related
I want to use two JPanels in one JFrame, with an invisible horizontal line between them. I played a little bit and got this:
public class Application {
public static void main(String[] args)
{
JFrame jframe = new JFrame();
jframe.setSize(500,700);
jframe.setVisible(true);
jframe.setTitle("Title");
jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jframe.setResizable(false);
JSplitPane splitPane = new JSplitPane();
JPanel leftPanel = new JPanel();
JPanel rightPanel = new JPanel();
splitPane.setOrientation(JSplitPane.HORIZONTAL_SPLIT);
splitPane.setDividerLocation(250);
splitPane.setLeftComponent(leftPanel);
splitPane.setRightComponent(rightPanel);
jframe.add(splitPane);
}
}
Now, the first problem is how can I turn off the "resizability" of the Line between the panels? And how do I make it "invisible"? Maybe use something else than split pane?
Second of all, how do can I work with only one side of the JPanel?
(I am working on an application that lets you draw a circle on the left hand side).
This seems like an easy question but I am relatively new to Java.
As said before in a comment by #MadProgrammer you can use BorderLayout or GridBagLayout but as you're placing the "split" line right in the middle of both panels you could use GridLayout which will make both panels be of the same size no matter if the window is resized.
I didn't tried with GridBagLayout but I did an example on how you could achieve this pane separation without using a JSplitPane.
With GridLayout all you need to do is add the elements to the left pane (in my example I used a JLabel to differentiate them) while in BorderLayout you need to specify that the panel where you'll be painting the circle to be aligned to the left (WEST constant) as I did.
However if you use BorderLayout approach and add text or elements to the right pane, they will be aligned to the right, you can fix it by "boxing" the elements in another pane with a different Layout.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Application {
private JFrame frame;
private JPanel containerPane;
private JPanel topPane;
private JPanel bottomPane;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Application().createAndShowGui();
}
});
}
public void createAndShowGui() {
frame = new JFrame("Example of 2 panels");
containerPane = new JPanel();
topPane = new JPanel();
bottomPane = new JPanel();
containerPane.setLayout(new GridLayout(2, 1));
topPane.setLayout(new GridLayout(1, 2));
bottomPane.setLayout(new BorderLayout());
topPane.add(new JLabel("Left side"));
topPane.add(new JLabel("Right side"));
bottomPane.add(new JLabel("Left side"), BorderLayout.WEST);
bottomPane.add(new JLabel("Right side"), BorderLayout.EAST);
topPane.setBorder(BorderFactory.createTitledBorder(BorderFactory.createLineBorder(Color.BLUE), "Using GridLayout"));
bottomPane.setBorder(BorderFactory.createTitledBorder(BorderFactory.createLineBorder(Color.BLUE), "Using BorderLayout"));
containerPane.add(topPane);
containerPane.add(bottomPane);
frame.add(containerPane);
// frame.pack();
frame.setSize(500, 400);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
I didn't call pack() in this example because the size of both panels (or JLabels in this case was not tall enough to show the difference:
Using pack():
Calling setSize():
Additional tips
Don't forget to place your program on the Event Dispatch Thread (EDT), I did it by writing these lines on the main method:
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Application().createAndShowGui();
}
});
Don't place all your code on the constructor, otherwise it will be hard to maintain
It looks like you can use GridLayout to do this. Here is what i think,
public class Application {
public static void main(String[] args) {
JFrame jframe = new JFrame();
jframe.setTitle("Title");
jframe.setResizable(false);
//This creates one row and two equally divided columns
GridLayout gridLayout = new GridLayout(0, 2);
jframe.setLayout(gridLayout);
gridLayout.layoutContainer(jframe);
JPanel leftPanel = new JPanel();
leftPanel.add(new Label("Left side"));
jframe.add(leftPanel);
JPanel rightPanel = new JPanel();
rightPanel.add(new Label("Right side"));
jframe.add(rightPanel);
jframe.setSize(800, 500);
jframe.setVisible(true);
jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
Here is how it looks:
The panels will not resize as well as there is no line visible that seprates them.
So I am programming an application using Java Swing, and I am wondering how to make it so that when the entire application gets resized only certain panels get resized in various ways. Take a look at the two pictures below:
I have three vertical panels as you can see. Now when the application's height is extended all three panels heights should increase also, that works fine. However when the width is increased I want it so that only the middle panel's (which will be the "workspace") width is increased. Instead, as you can see, the last-to-be-added third panel on the right is the only one whose width increases.
How do I go about to make it so that only the middle JPanel stretches & shrinks as the entire window is resized in the x axis? Also, later I would like to make it so that this workspace panel isn't always going to be in the middle; as the user can move the other two panels around to customize the app to their own taste, such as to make the two other panels stacked up on top of each other to the left while the workspace is on the right. However regardless of where it is I want the workspace panel to be the one the resizes, how do I do that?
The trick is to call setResizeWeight(double) on the correct split pane with the appropriate value. E.G.
import java.awt.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
public class DualingSplitPanes {
private JComponent ui = null;
DualingSplitPanes() {
initUI();
}
protected final void addPanelsToUi(JPanel p1, JPanel p2, JPanel p3) {
JSplitPane sp1 = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, p1, p2);
JSplitPane sp2 = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, sp1, p3);
sp2.setResizeWeight(1);
ui.add(sp2);
}
public void initUI() {
if (ui!=null) return;
ui = new JPanel(new BorderLayout(4,4));
ui.setBorder(new EmptyBorder(4,4,4,4));
JPanel treeContainer = new JPanel(new GridLayout());
JTree tree = new JTree();
tree.setVisibleRowCount(5);
for (int i=tree.getVisibleRowCount()-1; i>-1; i--) {
tree.expandRow(i);
}
treeContainer.add(new JScrollPane(tree));
JPanel workSpaceContainer = new JPanel(new GridLayout());
workSpaceContainer.add(new JTextArea(5, 10));
JPanel searchContainer = new JPanel(new BorderLayout(4, 4));
searchContainer.add(new JScrollPane(new JTextArea(5, 10)));
addPanelsToUi(treeContainer, workSpaceContainer, searchContainer);
}
public JComponent getUI() {
return ui;
}
public static void main(String[] args) {
Runnable r = new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (Exception useDefault) {
}
DualingSplitPanes o = new DualingSplitPanes();
JFrame f = new JFrame(o.getClass().getSimpleName());
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
f.setLocationByPlatform(true);
f.setContentPane(o.getUI());
f.pack();
f.setMinimumSize(f.getSize());
f.setVisible(true);
}
};
SwingUtilities.invokeLater(r);
}
}
You can make the constrains of the boxes so they are dependent of their corresponding side of the window.
So the left pane is X pixels from the left, and the right pane is Y pixels from the right, and then the middle one is constrained by having the left side X+ from the left, and the right side Y+ from the right.
This works as long as you don't resize the window too small (because then the elements get too big).
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.
I am trying to place a JPanel on top of another JPanel which contains a JTextArea and a button and i want to the upper apnel to be transparent. I have tried it by making the setOpaque(false) of the upper panel. but it is not working. Can anyone help me to get through this? Thanks in advance!
public class JpanelTest extends JPanel
{
public JpanelTest()
{
super();
onInit();
}
private void onInit()
{
setLayout(new BorderLayout());
JPanel panel = new JPanel();
panel.setLayout(new BorderLayout());
panel.add(new JTextArea(100,100),BorderLayout.CENTER);
panel.add(new JButton("submit"),BorderLayout.SOUTH);
JPanel glass = new JPanel();
glass.setOpaque(false);
add(panel,BorderLayout.CENTER);
add(glass,BorderLayout.CENTER);
setVisible(true);
}
public static void main(String args[])
{
new JpanelTest();
}
}
Indeed, it would be useful to tell the reason why you want panels one over another.
Starting with your code, and changing it a lot, I got it to work, but it might not do what you expect...
import java.awt.*;
import javax.swing.*;
public class Test extends JFrame
{
public Test()
{
super();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(500, 200);
onInit();
setVisible(true);
}
private void onInit()
{
JLayeredPane lp = getLayeredPane();
JPanel panel = new JPanel();
panel.setLayout(new BorderLayout());
panel.add(new JTextArea(), BorderLayout.CENTER);
panel.add(new JButton("Submit"), BorderLayout.SOUTH);
panel.setSize(300, 150); // Size is needed here, as there is no layout in lp
JPanel glass = new JPanel();
glass.setOpaque(false); // Set to true to see it
glass.setBackground(Color.GREEN);
glass.setSize(300, 150);
glass.setLocation(10, 10);
lp.add(panel, Integer.valueOf(1));
lp.add(glass, Integer.valueOf(2));
}
public static void main(String args[])
{
// Schedule a job for the event-dispatching thread:
// creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
new Test();
}
});
}
}
If totally transparent, well, it is like it isn't here! When opaque, it just covers some of the GUI, but doesn't prevent mouse clicks, for example.
1) there are a few ways, there no issue to put JPanel, with covering full JFrames/JPanel area or only part of Rectangle / Dimension that returns JFrames/JPanel
use JLayer(Java7) based on JXLayer (Java6)
use GlassPane
use JViewport
use OverlayLayout
use transucent JDialog / JWindow
2) everything depends of if you want to protect against mouse and key events from the top layer to bottom, or not (to avoiding redispatch events from - to and vice versa)
Check out this tutorial on using Swing Root Panes.
The glass pane is useful when you want to be able to catch events or paint over an area that already contains one or more components. For example, you can deactivate mouse events for a multi-component region by having the glass pane intercept the events. Or you can display an image over multiple components using the glass pane.