I am trying to make a class in which I can create a JFrame by calling different methods to build upon it. However somewhere along the lines my JTextArea is getting lost...
Below is a class called App which holds the methods I need to start building...
public class App {
private JFrame frame = new JFrame();
private JTextArea textArea = new JTextArea();
private JScrollPane scrollPane = new JScrollPane();
public void openJFrame(String title, int x, int y){
JFrame.setDefaultLookAndFeelDecorated(true);
frame.setTitle(title);
frame.setSize(x, y);
frame.setResizable(false);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public JFrame getJFrame(){
return frame;
}
public void addJTextArea(JScrollPane scrollPane){
scrollPane.add(textArea);
textArea.setLineWrap(true);
textArea.setEditable(true);
textArea.setVisible(true);
}
public JTextArea getJTextArea(){
return textArea;
}
public void addJScrollPane(JFrame frame){
frame.add(scrollPane);
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
}
public JScrollPane getJScrollPane(){
return scrollPane;
}
I would like to call this class from my main method and build a JFrame. Below is my attempt.
public class Main {
public static void main(String[] args){
App app = new App();
app.addJTextArea(app.getJScrollPane());
app.addJScrollPane(app.getJFrame());
app.openJFrame("title", 500, 500);
}
What happense is the JFrame and ScrollPane appear.. however my text area doesnt seem to be adding to the scroll pane.
Am I misunderstanding or overlooking something? It may be worth noting that if in the addJTextArea method I add it directly onto the JFrame without using the JScrollPane method it appears (obviously without the scroll pane)
Although JScrollPane may look/act/sound similar to a JPanel, it is not. And thus, using JScrollPane.add() to add a component to the scroll pane may sound natural, but is wrong. JScrollPane can only have one component inside that it scrolls around, and thus add() is wrong, but setViewportView() is the method to use.
You have to adapt your method addJTextArea to use scrollPane.setViewportView() instead of scrollPane.add():
public void addJTextArea(JScrollPane scrollPane){
scrollPane.setViewportView(textArea);
textArea.setLineWrap(true);
textArea.setEditable(true);
textArea.setVisible(true);
}
Replace scrollPane.add(textArea); with scrollPane.setViewportView(textArea);.
For more details read How to Use Scroll Panes
Related
JScrollPane works perfectly when I give it a JPanel and then add the JScrollPane directly on to a JFrame with frame.getContentPane.add(). However, it doesn't work when I add the JScrollPane to a JPanel and then add the JPanel to the JFrame. I need to use the second method because I'm going to add multiple things inside the JPanel and JFrame and I need to keep it organized. Here is my code.
import java.awt.*;
import javax.swing.*;
public class Main {
/**
* #param inpanel asks if the JScrollPane should
* be inside of a JPanel (so other things can also be added)
*/
public static void testScroll(boolean inpanel) {
JFrame f = new JFrame();
f.setLayout(new BorderLayout());
f.setResizable(true);
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
JPanel panel = new JPanel();
panel.setBorder(BorderFactory.createLineBorder(Color.red));
//panel.setLayout(new BoxLayout(panel, 1));
panel.setLayout(new GridLayout(0,1));
for (int i = 0; i < 100; i++) {
JLabel l = new JLabel("hey"+i,SwingConstants.CENTER);
l.setBorder(BorderFactory.createLineBorder(Color.green));
l.setPreferredSize(new Dimension(200,200));
panel.add(l);
}
JScrollPane scrollPane = new JScrollPane(panel);
scrollPane.setBorder(BorderFactory.createLineBorder(Color.blue));
//**********THIS DOES NOT WORK HOW I WANT IT TO************
if(inpanel){
JPanel holder = new JPanel();
holder.add(scrollPane);
f.getContentPane().add(holder);
}
//************THIS DOES WORK HOW I WANT IT TO****************
else{
f.getContentPane().add(scrollPane);
}
f.pack();
f.setSize(500, 500);
f.setExtendedState(JFrame.MAXIMIZED_BOTH);
f.setVisible(true);
JScrollBar bar = scrollPane.getVerticalScrollBar();
bar.setValue(bar.getMaximum());
bar.setUnitIncrement(50);
}
public static void main(String[] args) {
Runnable r = new Runnable() {
#Override
public void run() {
testScroll(false); //OR TRUE
}
};
SwingUtilities.invokeLater(r);
}
}
In the main method, if I pass false, it works like I mentioned before, but when I pass true it shows up without a scroll bar.
Picture when passing false
Picture when passing true
I need a way to add the JScrollPane to a JPanel and still have it work.
Thanks in advance!
Your problem is the holder JPanel's layout. By default it is FlowLayout which will not re-size its child components when need be. Make it a BorderLayout instead, and your scrollpane will resize when needed. If you need something more complex, check out the layout manager tutorials.
I'm trying to add the ScrollPane to my TextArea, but it doesn't appear.
Here's the code:
import javax.swing.*;
public class PracownikGui extends JFrame {
private JPanel Panelek;
private JTextArea Tekscik;
private JScrollPane Skrol;
public PracownikGui() {
setMinimumSize(new Dimension(600, 600));
setLocationRelativeTo(null);
setContentPane(Panelek);
setResizable(false);
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
Tekscik();
public void Tekscik() {
Tekscik = new JTextArea(2, 10);
Skrol = new JScrollPane( Tekscik );
Tekscik.setSize(300, 300);
Tekscik.setLocation(20, 70);
Tekscik.setEditable(true);
Tekscik.setLineWrap(true);
add(Tekscik);
}}
Any help, please.
You're shooting yourself in the foot by setting a JTextArea's size or preferredSize since this prevents it from expanding into the JScrollPane:
Tekscik.setSize(300, 300);
set its rows and columns only.
Also you need to add the JScrollPane to the GUI, not the JTextArea.
Also, while null layouts and setBounds() or setSize(...) and setLocation(...) might seem to Swing newbies like the easiest and best way to create complex GUI's, the more Swing GUI'S you create the more serious difficulties you will run into when using them. They won't resize your components when the GUI resizes, they are a royal witch to enhance or maintain, they fail completely when placed in scrollpanes, they look gawd-awful when viewed on all platforms or screen resolutions that are different from the original one.
e.g.,
import javax.swing.*;
public class PracownikPanel extends JPanel {
private JTextArea tekscik = new JTextArea(5, 25);
public PracownikPanel() {
tekscik.setLineWrap(true);
tekscik.setWrapStyleWord(true);
JScrollPane skrol = new JScrollPane(tekscik);
skrol.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
add(skrol);
}
private static void createAndShowGui() {
PracownikPanel mainPanel = new PracownikPanel();
JFrame frame = new JFrame("PracownikPanel");
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();
}
});
}
}
I made quite a few changes to your code. Your code wouldn't run.
Here's the GUI I created.
As you can see, there's a vertical scroll bar. The default action for the scroll bar is that it doesn't appear until you've filled the JTextArea with text.
Here are the important changes I made to your code.
Class names start with a capital letter. Method names and variable names start with a lower case letter.
A Swing application must start with a call to the SwingUtilities invokeLater method. This ensures that the Swing components are created and used on the Event Dispatch thread (EDT). Since the invokeLater method requires a Runnable, I had the PracownikGui class implement Runnable.
You use Swing components. You don't extend Swing components, or any other Java class, unless you want to override one of the methods in that class.
I removed all of the sizing and positioning statements, except for the statement that defines the rows and columns of the JTextArea. Hovercraft Full Of Eels explained this, but you use Swing layouts to get the arrangement of Swing components you want. The default layout for a JPanel is the FlowLayout. The default layout for a JFrame is the BorderLayout.
I added the JScrollPane to the JPanel. I added the JPanel to the JFrame.
Here's the code.
package com.ggl.testing;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
public class PracownikGui implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new PracownikGui());
}
private JFrame frame;
private JPanel panelek;
private JTextArea tekscik;
private JScrollPane skrol;
#Override
public void run() {
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
panelek = new JPanel();
tekscik(panelek);
frame.setContentPane(panelek);
frame.setResizable(false);
frame.pack();
frame.setVisible(true);
}
public void tekscik(JPanel panelek) {
tekscik = new JTextArea(2, 20);
tekscik.setEditable(true);
tekscik.setLineWrap(true);
skrol = new JScrollPane(tekscik);
panelek.add(skrol);
}
}
I'm making some test code to practice OOP, and I want to append a JTextArea from the "writeToArea" to the "initialize" method where the JTextArea is defined and initialized. I already tried to directly call the "output" variable, but this returns an "output cannot be resolved" error. I want so that whenever I call the "writeToArea" method in the main class, I'll be able to add lines to the "output" JTextArea in the "initialize" method.
Here's the main class:
public class Pangea {
public static void main(String[] args) {
UI.initialize();
UI.writeToArea();
}
}
Here's the initialize class:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
public class UI {
static void initialize() {
System.out.println("Initializing GUI.");
JFrame frame = new JFrame();
Font myFont = new Font("Courier", Font.BOLD, 14);
JTextField input = new JTextField("");
JTextArea output = new JTextArea("Initiated Succesfully.");
output.setWrapStyleWord(true);
output.setLineWrap(true);
input.setFont(myFont);
output.setFont(myFont);
input.setForeground(Color.WHITE);
output.setForeground(Color.WHITE);
input.setBackground(Color.BLACK);
input.setCaretColor(Color.WHITE);
output.setBackground(Color.BLACK);
output.setEditable(false);
JScrollPane jp = new JScrollPane(output);
frame.setTitle("PANGEA RPG [0.01 ALPHA][WIP]");
frame.setResizable(false);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(input, BorderLayout.SOUTH);
frame.add(jp, BorderLayout.CENTER);
frame.pack();
frame.setSize(800, 500);
frame.setVisible(true);
System.out.println("GUI Initialized.");
}
static void writeToArea() {
System.out.println("\"writeToArea\" running.");
output.append("Hello!");
System.out.println("\"writeToArea\" finished.");
}
}
I've tried to do something similar to this: Updating jtextarea from another class but it didn't work. If anyone has any suggestions I'd be very thankful.
The main error in your code is the lack of OOP design. Making all static is poor design.
Also swing is event based, so you should append text to the textArea when an event happens. See the example i write for you.
public class UI {
private JPanel panel;
private JTextArea output;
public UI(){
initialize();
}
private void initialize() {
panel = new JPanel();
Font myFont = new Font("Courier", Font.BOLD, 14);
final JTextField input = new JTextField(""); // must be declared final cause you use it in anonymous class, you can make it instance variable if you want to as textArea
//add an actionListener then when you press enter this will write to textArea
input.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent evt){
writeToArea(input.getText());
}
});
output = new JTextArea("Initiated Succesfully",50,100);// let the component determinate its preferred size.
output.setWrapStyleWord(true);
output.setLineWrap(true);
input.setFont(myFont);
output.setFont(myFont);
input.setForeground(Color.WHITE);
output.setForeground(Color.WHITE);
input.setBackground(Color.BLACK);
input.setCaretColor(Color.WHITE);
output.setBackground(Color.BLACK);
output.setEditable(false);
JScrollPane jp = new JScrollPane(output);
panel.setLayout(new BorderLayout());
panel.add(input, BorderLayout.SOUTH);
panel.add(jp, BorderLayout.CENTER);
}
private void writeToArea(String something) {
System.out.println("\"writeToArea\" running.");
output.append(something);
System.out.println("\"writeToArea\" finished.");
}
public JPanel getPanel(){
return panel;
}
}
And in your client code
public class Pangea {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable(){
#Override
public void run(){
createAndShowGUI();
}
});
}
/**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event dispatch thread.
*/
private static void createAndShowGUI() {
//Create and set up the window.
System.out.println("Initializing GUI.");
JFrame frame = new JFrame();
frame.setTitle("PANGEA RPG [0.01 ALPHA][WIP]");
frame.setResizable(false);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Add contents to the window.
frame.add(new UI().getPanel());
frame.pack();//sizes the frame
frame.setVisible(true);
System.out.println("GUI Initialized.");
}
}
Here you have a tutorial with better examples than this How to Use Text Areas
I remove your setSize and use pack()
The pack method sizes the frame so that all its contents are at or
above their preferred sizes. An alternative to pack is
to establish a frame size explicitly by calling setSize or setBounds
(which also sets the frame location). In general, using pack is
preferable to calling setSize, since pack leaves the frame layout
manager in charge of the frame size, and layout managers are good at
adjusting to platform dependencies and other factors that affect
component size.
Read the section from the Swing tutorial on How to Use Text Areas. It will show you how to better structure your code so that you don't use static methods and variables everywhere.
Once you have a panel that has a reference to the text area you can add methods that allow you to update the text area on the panel.
I have following problem. Is there a way to scroll Jframe content without using scrollbars, just to do it programatically in code. I have Japplet inside and I can't find a way to scroll its content without showing scrolls. Whole scrolling action should be performed not on user action, but when my thread wants to do so. Waiting for help, thanks.
I can't find any way to do that. I was trying to add my component (Applet) to Jscrollpane and that to jframe, but it causes situation, when only white screen is displayed.
JFrame class:
public class SimulationFrame extends JFrame {
private SimulationWindow simulationWindow;
public SimulationFrame() throws HeadlessException {
super(PropertiesHelper.getWindowTitle());
simulationWindow = new SimulationWindow();
JScrollPane scrollPane = new JScrollPane(simulationWindow);
this.getContentPane().add(scrollPane);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.pack();
this.setVisible(true);
}
}
JComponent:
public SimulationWindow() {
setLayout(new BorderLayout());
graph = GraphHelper.provideGraphInstance();
Dimension layoutSize = new Dimension(PropertiesHelper.getGraphHolderWidth(),
PropertiesHelper.getGraphHolderHeight());
graphLayout = new StaticLayout<Checkpoint, Route>(graph, new CheckpointPositionTransformer());
graphLayout.setSize(layoutSize);
visualizationViewer = new VisualizationViewer<Checkpoint, Route>(graphLayout, new Dimension(
PropertiesHelper.getWindowWidth(), PropertiesHelper.getWindowHeight()));
visualizationViewer.getRenderContext().setVertexLabelTransformer(new CheckpointLabelTransformer());
visualizationViewer.getRenderer().getVertexLabelRenderer().setPosition(Renderer.VertexLabel.Position.CNTR);
visualizationViewer.getRenderContext().setVertexFillPaintTransformer(new CheckpointColorTransformer());
visualizationViewer.getRenderContext().setEdgeDrawPaintTransformer(new RouteColorTransformer());
visualizationViewer.getRenderContext().setEdgeLabelTransformer(new RouteLabelTransformer());
final ImageIcon mapBackground = createMapBackground();
if (mapBackground != null) {
mapBackgroundImagePaintable = new BackgroundImagePaintable(visualizationViewer, mapBackground);
visualizationViewer.addPreRenderPaintable(mapBackgroundImagePaintable);
}
add(visualizationViewer);
scrollRectToVisible(new Rectangle(1000,100));
}
VisualizationViewer is a class that extends JPanel. Placing scrollRectToVisible in this constructor didn't works.
Any tips? Perhaps this implementation is wrong, where Jcomponent contains Jpanel itself?
Use method
public void scrollRectToVisible(Rectangle aRect)
of the JComponent added in JScrollPane
If I add a JTable to a JPanel and then add that JPanel to a JScrollPane, whenever that JTable gains focus, the scroll pane automatically scrolls to the very bottom, which is bad.
I have many reasons for doing it like this, so I'm hoping for some kind solution to stop this auto-scrolling.
OH, and here's the kicker...It only seems to happen when running the app through JNLP/WebStart, and it does NOT do it in Eclipse, which is even more frustrating.
Here's a quick example that if you launch through JLNP, click the text field, click the table, then it auto-scrolls to the bottom:
import java.awt.*;
import javax.swing.*;
public class ScrollDemo extends JPanel{
private static final long serialVersionUID = 1L;
public ScrollDemo()
{
this.setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS));
JTable table = new JTable(100,6);
this.add(new JTextField());
JPanel panel = new JPanel();
panel.add(table);
JScrollPane scroll = new JScrollPane(panel);
this.add(scroll);
}
/**
* Create the GUI and show it. For thread safety, this method should be
* invoked from the event-dispatching thread.
*/
private static void createAndShowGUI() {
// Create and set up the window.
JFrame frame = new JFrame("ScrollDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Create and set up the content pane.
JComponent newContentPane = new ScrollDemo();
newContentPane.setOpaque(true); // content panes must be opaque
frame.setContentPane(newContentPane);
frame.setPreferredSize(new Dimension(500, 500));
// Display the window.
frame.pack();
frame.setVisible(true);
}
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() {
createAndShowGUI();
}
});
}
}
I am unable to reproduce the problem, but I can offer a few observations:
The frame's add() method forwards the component to the contentPane automatically.
Instead of setting the frame's preferred size, use setPreferredScrollableViewportSize() on the table.
If the unwanted scrolling is due to updating the table's model, see this example of how to temporarily suspend scrolling.
Kudos for using the event dispatch thread.
Addendum: The nested panel having a (default) FlowLayout is superfluous.
import java.awt.*;
import javax.swing.*;
/** #see https://stackoverflow.com/questions/8319388 */
public class ScrollDemo extends JPanel {
public ScrollDemo() {
this.setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS));
JTable table = new JTable(100, 6);
table.setPreferredScrollableViewportSize(new Dimension(320, 240));
this.add(new JTextField());
this.add(new JScrollPane(table));
}
private static void createAndShowGUI() {
// Create and set up the window.
JFrame frame = new JFrame("ScrollDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Create and set up the content pane.
frame.add(new ScrollDemo());
frame.pack();
// Display the window.
frame.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
createAndShowGUI();
}
});
}
}
Just in case anyone cares, the problem was that the eclipse launcher and the JNLP launcher for the app had a different KeyboardFocusManager, and the JNLP one had some quirks.
I was unaware of a custom KeyboardFocusManager being added on the JLNP side, but at least it explains things.
Thanks everyone.
I have had auto scrolling issue on JTables when I place them on an intermediary JPanel instead of placing them directly as the JScrollPane's viewport. In those cases, removing the extraneous panel and putting the table directly on the scrollpane has solved my issues.
Well, I ended up having to rework how I was adding my objects to the scroll pane to avoid this issue. Specifically, if the table is going to be taller than the viewport height, then I just have to add the table directly to the scrollpane then change how I was using the intermediary panel.
Thanks to everyone for your input!
According to this, to change the selection for your JTable you need to change the selection model. Try using the following to set the selected item to the very first one.
ListSelectionModel selectionModel = table.getSelectionModel();
selectionModel.setSelectionInterval(start, end);
See if that gives the focus to the top of the JTable?
EDIT: I have not done this before, so not sure what start and end will need to be, try 0,0 or 0,1 maybe?