I'm having what I am sure is very much a beginners problem with my JScrollPanes. The problem is that the vertical scrollbar overlaps the components within the enclosed panel (on the right hand side). It becomes a bit of a pain when the scrollbar overlaps the drop-down bit of JComboBoxes.
I have boiled the problem down to this little snippet - I hope it illustrates the issue.
public class ScrollTest extends JFrame
{
public ScrollTest()
{
super("Overlap issues!");
JPanel panel = new JPanel();
panel.setLayout(new GridLayout(100,0));
for(int b=0;b<100;++b)
{
panel.add(new JButton("Small overlap here ->"));
}
JScrollPane scrollpane = new JScrollPane(panel);
add(scrollpane);
pack();
setVisible(true);
}
public static void main(String[] args)
{
new ScrollTest();
}
}
I had a look first but couldn't see if anyone else had already addressed this problem. Sorry if it's a duplicate and many thanks for any help anyone can offer a java-newb like me!
The problem is that the default for a JScrollPane is to layout the components with a default of JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED which in turn adds the scrollbar without laying out the components again.
In your example you know you will need a scrollbar so change it to always display the scrollbar
public class ScrollTest extends JFrame
{
public ScrollTest()
{
super("Overlap issues!");
JPanel panel = new JPanel();
//Insets insets = panel.getInsets();
//insets.set(5, 5, 5, 25);
//insets.set(top, left, bottom, right);
panel.setLayout(new GridLayout(100,0));
for(int b=0;b<100;++b)
{
panel.add(new JButton("Small overlap here ->"));
}
JScrollPane scrollpane = new JScrollPane(panel);
scrollpane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
add(scrollpane);
pack();
setVisible(true);
}
public static void main(String[] args)
{
new ScrollTest();
}
}
Related
i been working on some bigger project lately but couldn't figure it out why JScrollPane wouldn't work. I have never used it before and I read many solved problems about it on stackOverflow and other programming forums but non of the code were looking similar to mine to help me implement my method.
this is new project i made to make it short and show some examples.
Red colour is main panel that will contain another panel/JScrollPane inside that will be colour black
and i would like to make this Jpanel with colour black to be scrollable and hold any number of that white JPanels that might be from 0 to a 100+
public class ScrollablePane {
private JFrame frame;
private JPanel panelCopy;
private JPanel panel;
private JPanel container;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
ScrollablePane window = new ScrollablePane();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public ScrollablePane() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
panel = new JPanel();
panel.setBackground(Color.RED);
panel.setBounds(0, 0, 434, 261);
frame.getContentPane().add(panel);
panel.setLayout(null);
container = new JPanel();
container.setBackground(Color.BLACK);
container.setBounds(10, 10, 414, 241);
container.setLayout(new FlowLayout(FlowLayout.CENTER, 10, 10));
panel.add(container);
for(int i = 0; i < 20; i++) {
if(i > 0) {
panelCopy = new JPanel();
panelCopy.setPreferredSize(new Dimension(400, 40));
container.add(panelCopy);
}
}
}
}
if you want to use a JScrollPane, then your code actually needs to use a JScrollPane. The code you posted doesn't even create a JScrollPane.
If you want the panels to display vertically then don't use a FlowLayout. The FlowLayout is a horizontal layout. You could use a BoxLayout or a GridBagLayout.
Why do you create the "panel" variable and add it the the content pane? The content pane of the frame already is a JPanel that uses a BorderLayout. There is no need to add another panel
Don't use a null layout!!! Swing was designed to be used with layout managers. Scrolling won't work if the panel added to the scroll pane uses a null layout.
So in your case the basic logic might be something like:
Box container = Box.createVerticalBox();
// add you child panels to the container.
JPanel wrapper = new JPanel( new BorderLayout() );
wrapper.add(container, BorderLayout.PAGE_START);
JScrollPane scrollPane = new JScrollPane(wrapper);
frame.add(scrollPane, BorderLayout.CENTER);
Note the "wrapper" panel is used to prevent the panels from expanding in size when the scroll pane is larger then the preferred size of the "container" panel.
Try:
//JScrollPane scrollPane = new JScrollPane(wrapper);
JScrollPane scrollPane = new JScrollPane(container);
to see the different result.
I've tried a lot of different ways, but I will explain two and what was happening (no error messages or anything, just not showing up like they should or just not showing up at all):
First, I created a JPanel called layout and set it as a BorderLayout. Here is a snippet of how I made it look:
JPanel layout = new JPanel();
layout.setLayout(new BorderLayout());
colorChoice = new JLabel("Choose your color: ");
layout.add(colorChoice, BorderLayout.NORTH);
colorBox = new JComboBox(fireworkColors);
colorBox.addActionListener(this);
layout.add(colorBox, BorderLayout.NORTH);
In this scenario what happens is they don't show up at all. It just continues on with whatever else I added.
So then I just tried setLayout(new BorderLayout()); Here is a snippet of that code:
setLayout(new BorderLayout());
colorChoice = new JLabel("Choose your color: ");
add(colorChoice, BorderLayout.NORTH);
colorBox = new JComboBox(fireworkColors);
colorBox.addActionListener(this);
add(colorBox, BorderLayout.NORTH);
In this scenario they are added, however, the width takes up the entire width of the frame and the textfield (not shown in the snippet) takes up basically everything else.
Here is what I have tried:
setPreferredSize() & setSize()
Is there something else that I am missing? Thank you.
I also should note that this is a separate class and there is no main in this class. I only say this because I've extended JPanel instead of JFrame. I've seen some people extend JFrame and use JFrame, but I haven't tried it yet.
You created a JPanel, but didn't add it to any container. It won't be visible until it is added to something (a JFrame, or another panel that is in a frame somewhere up the hierarhcy)
You added two components to the same position in the BorderLayout. The last one added is the one that will occupy that position.
Update:
You do not need to extend JFrame. I never do, instead I always extend JPanel. This makes my custom components more flexible: they can be added in another panel, or they can be added to a frame.
So, to demonstrate the problem I will make an entire, small, program:
public class BadGui
{
public static void main(String[] argv)
{
final JFrame frame = new JFrame("Hello World");
final JPanel panel = new JPanel();
panel.add(new JLabel("Hello"), BorderLayout.NORTH);
panel.add(new JLabel("World"), BorderLayout.SOUTH);
frame.setVisible(true);
}
}
In this program I created a panel, but did not add it to anything so it never becomes visible.
In the next program I will fix it by adding the panel to the frame.
public class FixedGui
{
public static void main(String[] argv)
{
final JFrame frame = new JFrame("Hello World");
final JPanel panel = new JPanel();
panel.add(new JLabel("Hello"), BorderLayout.NORTH);
panel.add(new JLabel("World"), BorderLayout.SOUTH);
frame.getContentPane().add(panel);
frame.setVisible(true);
}
}
Note that in both of these, when I added something to the panel, I chose different layout parameters (one label I put in 'North' and the other in 'South').
Here is an example of a JPanel with a BorderLayout that adds a JPanel with a button and label to the "North"
public class Frames extends JFrame
{
public Frames()
{
JPanel homePanel = new JPanel(new BorderLayout());
JPanel northContainerPanel = new JPanel(new FlowLayout());
JButton yourBtn = new JButton("I Do Nothing");
JLabel yourLabel = new JLabel("I Say Stuff");
homePanel.add(northContainerPanel, BorderLayout.NORTH);
northContainerPanel.add(yourBtn);
northContainerPanel.add(yourLabel);
add(homePanel);
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
setLocationRelativeTo(null);
setExtendedState(JFrame.MAXIMIZED_BOTH);
setTitle("Cool Stuff");
pack();
setVisible(true);
}
public static void main(String[] args)
{
SwingUtilities.invokeLater(Frames::new);
}
}
The below suggestion is assuming that your extending JFrame.
Testing
First of all, without seeing everything, theres always a numerous amount of things you can try.
First off, after you load everything, try adding this in (Again, assuming your extending JFrame:
revalidate();
repaint();
I add this into my own Swing projects all the time, as it refreshes and checks to see that everything is on the frame.
If that doesn't work, make sure that all your JComponent's are added to your JPanel, and ONLY your JPanel is on your JFrame. Your JFrame cannot sort everything out; the JPanel does that.
JPanel window = new JPanel();
JButton button = new JButton("Press me");
add(window);
window.add(button); // Notice how it's the JPanel that holds my components.
One thing though, you still add your JMenu's and what-not through your JFrame, not your JPanel.
I'm trying to understand how Java.awt works (we need to create a GUI without GUI editor)
the following code does not show 2 TextAreas:
Frame fr = new Frame("Parser");
Panel buttons = new Panel();
Panel inputText = new Panel();
Panel outputText = new Panel();
String here = new String ("Insert code here...");
TextArea input = new TextArea(here, 9, 96, TextArea.SCROLLBARS_VERTICAL_ONLY);
TextArea output = new TextArea(here, 9,96,TextArea.SCROLLBARS_VERTICAL_ONLY);
public Window(){
fr.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent we) {
fr.dispose();
}
}
);
fr.setSize(700, 400);
fr.setLocation(200,100);
fr.setResizable(false);
fr.add(buttons);
fr.add(inputText);
fr.add(outputText);
buttons.setBounds(new Rectangle(0,0,700,60));
buttons.setBackground(new Color(200,200,200));
inputText.setBounds(new Rectangle(0,60,700,170));
inputText.setBackground(new Color(255,255,255));
inputText.add(input);
outputText.setBounds(new Rectangle(0,230,700,170));
outputText.setBackground(new Color(200,200,200));
outputText.add(output);
}
Obtained result:
Expected result:
Your code does not respect the layout managers that your containers are using. I believe that AWT Frames use a BorderLayout by default (edit: yes they do, per the Frame API. Suggestions:
In general avoid AWT for Swing which has much greater power and flexibility, although it too is showing its age, just less so than AWT.
Read up on and use layout managers in a smart way to do your heavy lifting for you. Here it looks like a BoxLayout could help you.
Avoid use of null layouts. While yes, that could offer you a quick and easy fix for your current code, it leads to the creation of very inflexible GUI's that while they might look good on one platform look terrible on most other platforms or screen resolutions and that are very difficult to update and maintain.
Avoid setting bounds, sizes or locations of any components, and again let the components and their container's layout managers set the sizes for you.
The Layout Manager Tutorial
For example:
import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.*;
public class MyWindow extends JPanel {
private static final int ROWS = 10;
private static final int COLS = 50;
private static final String[] BUTTON_NAMES = { "Monday", "Tuesday",
"Wednesday", "Thursday", "Friday" };
private static final int GAP = 3;
private JTextArea inputTextArea = new JTextArea(ROWS, COLS);
private JTextArea outputTextArea = new JTextArea(ROWS, COLS);
public MyWindow() {
JPanel buttonPanel = new JPanel(new GridLayout(1, 0, GAP, 0));
for (String btnName : BUTTON_NAMES) {
buttonPanel.add(new JButton(btnName));
}
outputTextArea.setFocusable(false);
outputTextArea.setEditable(false);
setBorder(BorderFactory.createEmptyBorder(GAP, GAP, GAP, GAP));
setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS));
add(buttonPanel);
add(putInTitledScrollPane(inputTextArea, "Input Text"));
add(putInTitledScrollPane(outputTextArea, "Output Text"));
}
private JPanel putInTitledScrollPane(JComponent component,
String title) {
JPanel wrapperPanel = new JPanel(new BorderLayout());
wrapperPanel.setBorder(BorderFactory.createTitledBorder(title));
wrapperPanel.add(new JScrollPane(component));
return wrapperPanel;
}
private static void createAndShowGui() {
MyWindow mainPanel = new MyWindow();
JFrame frame = new JFrame("MyWindow");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
Which displays as:
Use of layout managers gives you much greater ease when it comes to changing or enhancing your GUI. For example, since I'm setting my JTextArea's width with a COL constant, if I change the COL constant, the whole GUI widens, even the buttons and the button JPanel, since the layout managers are handling all the sizing. With your code, you'd have to manually change the width of every component added to the GUI, which is prone to bug creation.
Because you are manually laying out your components, you are needed to set layout to null (setLayout(null);)
so before adding any component add this line in your code.
fr.setLayout(null);
Now you will get this :
I am a beginer at programing and i wanted to add a scroll panel to a JTextArea so i tried to research tutorials online. i followed the examples but its not working can someone plz tell me what i am doing wrong. thank you so much
public View(Model model) {
this.model = model;
setBounds(100,50, 800, 400);
setDefaultCloseOperation(EXIT_ON_CLOSE);
Container c = getContentPane();
addDisplay(c);
addButtons(c);
addTxt(c);
}
private void addDisplay(Container c){
JPanel p = new JPanel();
addTxt2(p);
addTxt(p);
add(p, "North");
}
private void addTxt(JPanel p){
txt = new JTextArea(15, 35);
txt.setBackground(Color.BLACK);
txt.setForeground(Color.WHITE);
txt.setEditable(true);
JScrollPane scroll= new JScrollPane (txt);
p.add(scroll);
}
Always invoke revalidate and repaint after adding any components to a JPanel
p.add(scroll);
p.revalidate();
p.repaint();
From the use of setBounds, it appears that there is no layout manager in use. Don't use absolute positioning (null layout). By default, components have a size of 0 x 0 so will not appear unless their size is set. A layout manager should be used here instead.
Post an SSCCE for better help sooner
You have to set the bounds of your scroll setBounds(int, int, int, int)
and define the area of your JTextArea
Here's an example:
public class ScrollingTextArea extends JFrame {
JTextArea txt = new JTextArea();
JScrollPane scrolltxt = new JScrollPane(txt);
public ScrollingTextArea() {
setLayout(null);
scrolltxt.setBounds(3, 3, 300, 200);
add(scrolltxt);
}
public static void main(String[] args) {
ScrollingTextArea sta = new ScrollingTextArea();
sta.setSize(313,233);
sta.setTitle("Scrolling JTextArea with JScrollPane");
sta.show();
}
}
I've found it here
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.