Develop Reference

Scroll bar not working with my JTextArea

I have written a basic swing code in which I have wrapped a JTextArea into a JScrollPane. But still, the scroll bars won't show up even if the text area content goes out of visible JFrame area.
The code is as follows -
public class TestArea {
private JTextArea area;
private JScrollPane scroll;
private JFrame frame;
public TestArea(){
frame = new JFrame("Testing");
frame.setSize(new Dimension(200, 300));
area = new JTextArea();
area.setEditable(false);
scroll = new JScrollPane(area);
frame.getContentPane().add(scroll);
area.setLayout(new BoxLayout(area, BoxLayout.Y_AXIS));
area.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
area.setBackground(Color.WHITE);
addMessage();
}
private void addMessage() {
area.add(new JLabel("Can you see me..... can you see me"));
for(int i=0; i<30; i++){
area.add(new JLabel(Integer.toString(i)));
System.out.println(Integer.toString(i));
frame.setVisible(true);
}
}
public static void main(String[] args){
new TestArea();
}
}
The reason for using BoxLayout is that I strictly want the output to be aligned in y axis. Here is the link to the output screenshot https://app.box.com/s/rgeyajgvk0ppude399my
As you can see, the scroll bars are not appearing. Can anyone please help me with this?

JTextArea couldn't be container for JComponents, JLabels in this case
JTextArea is designated for plain text
use JPanel as contianer for arrays of JLabels instead of JTextArea

I was using JLabel because in between I intend to display strings in a different color
Then you should probably by using a JTextPane. It supports attributes (like bold, font, color) for each text string you add to the text pane.
Read the section from the Swing tutorial on Text Component Features for more information and examples.

How do I resize JScrollPane after resizing a JTextArea

My JFrame Consists of three main parts a banner at top scrollpane containing a JTextArea center and a JTextField at the bottom. When I re-size the frame I adjust the columns and rows in my JTextArea. When making the frame larger the JTextArea expands visually but removes the scroll-bar. Then if I make the frame smaller the JTextArea stays the same size. This Is where I attempt to re-size my JTextArea.
frame.addComponentListener(new ComponentAdapter() {//Waits for window to be resized by user
public void componentResized(ComponentEvent e) {
uneditTextArea.setRows(((int)((frame.getHeight()-140)/18.8)));//sets Textarea size based on window size
uneditTextArea.setColumns(((int)((frame.getWidth()-100)/10.8)));
frame.revalidate();//refreshes screen
}
});
Why would the ScrollPane not re adjust to the change in size of the TextField.
The Rest of the code is below in case it is needed.
public class window extends JFrame
{
private static JFrame frame = new JFrame("Lillian");
private static JButton inputButton = new JButton("Send");
private static JTextField editTextArea = new JTextField(46);
private static JTextArea uneditTextArea = new JTextArea(26,50);
private static JPanel logoPanel = new JPanel();//Input text window
private static JPanel itextPanel = new JPanel();//Input text window
private static JPanel submitPanel = new JPanel();//Submit Button
private static JPanel bottom = new JPanel();//will contain scrollpane
private static JPanel middle = new JPanel();//willcontain itextpanel & submitbutton
private static JPanel otextPanel = new JPanel();//Text Output
public static void runWindow()
{
ImageIcon logo = new ImageIcon("Lillian_resize.png");//banner
ImageIcon icon = new ImageIcon("Lillian_icon.png");//application icon
frame.setIconImage(icon.getImage());
frame.setSize(660,640);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
logoPanel.setSize(10,10);
JLabel logoLabel = new JLabel(logo);
final JScrollPane scrollPane = new JScrollPane(otextPanel);//adds text to panel will scrollbar
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);//scrollbar only apears when more text than screen
scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);//scrollbar never apears
scrollPane.setBorder(BorderFactory.createEmptyBorder());
logoPanel.add(logoLabel);
submitPanel.add(inputButton);
itextPanel.add(editTextArea);
otextPanel.add(uneditTextArea);
frame.getContentPane().add(logoPanel,"North");
frame.getContentPane().add(middle);
frame.getContentPane().add(bottom,"South");
middle.add(scrollPane,"North");//adds panels to outer panel
bottom.add(itextPanel, "West");
bottom.add(submitPanel, "East");
uneditTextArea.setLineWrap(true);
uneditTextArea.setWrapStyleWord(true);
uneditTextArea.setEditable(false);
uneditTextArea.setCaretPosition(uneditTextArea.getDocument().getLength());
frame.revalidate();//refreshes screen
//---------------wait for action------------
frame.addComponentListener(new ComponentAdapter() {//Waits for window to be resized by user
public void componentResized(ComponentEvent e) {
uneditTextArea.setRows(((int)((frame.getHeight()-140)/18.8)));//sets Textarea size based on window size
uneditTextArea.setColumns(((int)((frame.getWidth()-100)/10.8)));
frame.revalidate();//refreshes screen
}
});
}
}

There should be no need to use a ComponentListener to resize components. That is the job of the layout managers that you use to dynamically resize the components.
You should not be adding the text area to a JPanel first. Instead when using text areas you would generally add the text area directly to the viewport of a JScrollPane by using code like:
JScrollPane scrollPane = new JScrollPane( textArea );
Then you add the scrollpane to the frame with code like:
frame.add(scrollPane, BorderLayout.CENTER);
As you have noticed you should also NOT use hardcoded literals like "Center". Instead use the variables provided by the layout manager. Since you are using a BorderLayout, use the variables defined in the BorderLayout class.
Also, you should NOT be using static variable to create your GUI. I suggest you read the section from the Swing tutorial on Layout Manager. The tutorial will give you more information and the example code will show you how to better structure your program so that you don't need to use static variables.

Why is the window too small if I don't resize it?

I am wondering why when I enter this code without resizing the window, I cannot see anything:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class GolfScoresGUI
{
public static void main(String[] args)
{
JFrame frame = new JFrame("GolfScoresGUI");
JLabel label = new JLabel("Did you score it? ");
JTextField textField = new JTextField(10);
frame.setVisible(true);
frame.getContentPane().add(textField);
}
}

add your components to a panel on which you call setPreferredSize, add the panel to the frame and call JFrame.pack().
JFrame.pack() updates the size of the frame to take the minimum possible size, given the size on its contained elements.
If you don't call it, the size will be something like 0x0, explaining why you don't see anything.
JFrame frame = new JFrame("GolfScoresGUI");
JPanel panel=new JPanel();
panel.setPreferredSize(new Dimension(600,400)); // Not mandatory. Without this, the frame will take the size of the JLabel + JTextField
frame.add(panel);
JLabel label = new JLabel("Did you score it? ");
JTextField textField = new JTextField(10);
panel.add(label);
panel.add(textField);
frame.setVisible(true);
frame.pack();
EDIT
btw, you should also add this line so that your application stops when you close the frame :
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

Everything is fine but you are not specifying any size for that JFrame. That is the problem. Try giving frame.setSize(width,height), or frame.pack(). By using one of this your problem will be solved.
http://docs.oracle.com/javase/tutorial/uiswing/components/frame.html
have a look at this to know about using JFrame in detailed.
Be carefull while using setVisible(true). Try to place setVisible(true) at the end of your GUI code, i.e: use it after adding all the GUI components to the container, because some times when you are adding more components it will not display some components until the frame is resized.

How can I size a Java Swing JTextArea

I am trying to put a text area onto a dialog box using Java Swing. I have a problem of setting the size of this JTextArea. The width of the text area is always equal to the whole width of the window and stretches with the window if I resize it.
private void arrangeComponents() {
JTextArea textArea = new JTextArea();
JPanel outerPanel = new JPanel();
outerPanel.setLayout(new BoxLayout(outerPanel, BoxLayout.PAGE_AXIS));
JScrollPane scrollPane = new JScrollPane(textArea);
outerPanel.add(scrollPane, BorderLayout.CENTER);
Container contentPane = getContentPane();
contentPane.add(outerPanel, BorderLayout.CENTER);
}
I want the JTextArea to be horizontally aligned to the centre of the window and does not change its size.
What did I do wrong?

Use the JTextArea(int rows, int columns) constructor that specifies rows and columns, as shown here, and don't neglect to pack() the enclosing Window.

outerPanel.add(scrollPane, BorderLayout.CENTER);
A BoxLayout doesn't take constraints, so the BorderLayout.CENTER is unnecessary.
The problem is that a BoxLayout respects the maximum size of the component which for a scrollpane is set very large.
Instead of using a BoxLayout, just use a panel with a FlowLayout.
Run the example below to see what you are currently doing. Then comment out the setLayout(...) statement and run again. By default the panel uses a FlowLayout so you will get what you want.
import java.awt.*;
import javax.swing.*;
import javax.swing.text.*;
public class SSCCE extends JPanel
{
public SSCCE()
{
setLayout( new BoxLayout(this, BoxLayout.PAGE_AXIS));
JTextArea textArea = new JTextArea(5, 30);
JScrollPane scrollPane = new JScrollPane(textArea);
//scrollPane.setMaximumSize( scrollPane.getPreferredSize() );
add(scrollPane);
}
private static void createAndShowUI()
{
JFrame frame = new JFrame("SSCCE");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add( new SSCCE() );
frame.pack();
frame.setLocationRelativeTo( null );
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowUI();
}
});
}
}
Or if you really want to keep the BoxLayout then leave keep the setLayout(...) statement and then set the maximum size equal to the preffered size. Many people will say you should never invoke a "setXXX()" method directly and instead you should override the setMaximumSize() method of the scrollpane to just return the preferred size.
Note, when testing these two solutions make sure you make the window smaller than the scrollpane to see how each layout works differently.

i found this from a simple coding site. This code sample may be useful for you.
import java.awt.Dimension;
import java.awt.FlowLayout;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public class JTextAreaTest {
public static void main(String[] args) {
JFrame.setDefaultLookAndFeelDecorated(true);
JFrame frame = new JFrame("JTextArea Test");
frame.setLayout(new FlowLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
String text = "A JTextArea object represents a multiline area for displaying text. "
+ "You can change the number of lines that can be displayed at a time, "
+ "as well as the number of columns. You can wrap lines and words too. "
+ "You can also put your JTextArea in a JScrollPane to make it scrollable.";
JTextArea textAreal = new JTextArea(text, 5, 10);
textAreal.setPreferredSize(new Dimension(100, 100));
JTextArea textArea2 = new JTextArea(text, 5, 10);
textArea2.setPreferredSize(new Dimension(100, 100));
JScrollPane scrollPane = new JScrollPane(textArea2,
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
textAreal.setLineWrap(true);
textArea2.setLineWrap(true);
frame.add(textAreal);
frame.add(scrollPane);
frame.pack();
frame.setVisible(true);
}
}

Just call that method for ur text area: setLineWrap(true);

If JTextArea is initializated
JTextArea text = new JTextArea(int rows, int columns)
you just call the method text.setLineWrap(true)
then text'size is fixed.

JScrollBar Vertical/Horizontal setting problem- Java Swing

I am just trying to add a vertical scroll bar to my TextField and TextArea.
I am using a ScrollPane and it should create avertical/horizontal scroll bar by default.
Problem:
I need a vertical scroll bar to see the data which is not visible.
In the start a vertical scrollbar appears but when the data increases the vertical scrollbar changes to a horizontal scroll bar.
Also the TextField disappears and only a horizontal scrollbar appears in its place.
I guess it is because how I have set the bounds but I tried changing the bounds and it ends up completely doing away with the TextField.
My code snippet:
public JTextField inputField = new JTextField();
public JTextArea talkArea = new JTextArea();
public JScrollPane inputFieldScroll = new JScrollPane(inputField);
public JScrollPane talkAreaScroll = new JScrollPane(talkArea);
talkArea.setEditable(false);
talkArea.setBackground(Color.white);
talkAreaScroll.setBounds(new Rectangle(TALK_LEFT, TALK_TOP, TALK_WIDTH, TALK_HEIGHT));
this.getContentPane().add(talkAreaScroll, null);
//set input area
inputField.setBackground(Color.white);
inputField.setBounds(new Rectangle(INPUT_LEFT, INPUT_TOP, INPUT_WIDTH, INPUT_HEIGHT));
inputFieldScroll.setVerticalScrollBar(new JScrollBar());
inputFieldScroll.setBounds(new Rectangle(INPUT_LEFT, INPUT_TOP, INPUT_WIDTH, INPUT_HEIGHT));
Question:
Is there some parameter I need to set so that it remains a vertical scroll bar?
Why does the input scroll bar occupy the whole inputfield when the data becomes a huge line? It appears as a proper vertical scrollbar in the start.
Any advice appreciated.
Thanks

Below is a small compilable code snippet I mentioned above. I agree with camickr that you should not be using absolute positioning but rather use the layout managers. If you absolutely need to have a horizontal scrollbar for the JTextField, then one way to get it to work is to have it show up always, using the JScrollPane constructor that allows for this. i.e,
JScrollPane inputPane = new JScrollPane(inputField, JScrollPane.VERTICAL_SCROLLBAR_NEVER,
JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
For e.g.,
import java.awt.*;
import javax.swing.*;
public class FuSwing1b extends JPanel {
private static final int TA_ROWS = 25;
private static final int TA_COLS = 60;
private JTextField inputField = new JTextField();
private JTextArea talkArea = new JTextArea(TA_ROWS, TA_COLS);
public FuSwing1b() {
talkArea.setEditable(false);
talkArea.setFocusable(false);
talkArea.setBackground(Color.white);
//talkArea.setPreferredSize(new Dimension(TALK_WIDTH, TALK_HEIGHT));
JScrollPane talkPane = new JScrollPane(talkArea, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
JScrollPane inputPane = new JScrollPane(inputField, JScrollPane.VERTICAL_SCROLLBAR_NEVER,
JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
int gap = 10;
setLayout(new BorderLayout(gap, gap));
add(talkPane, BorderLayout.CENTER);
add(inputPane, BorderLayout.SOUTH);
setBorder(BorderFactory.createEmptyBorder(gap , gap, gap, gap));
}
private static void createAndShowUI() {
JFrame frame = new JFrame("FuSwing1b");
frame.getContentPane().add(new FuSwing1b());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
createAndShowUI();
}
});
}
}

Don't play with the bounds. Use a layout manager and you won't have to worry about this.
When you create the text field use something like:
JTextField textField = new JTextField(10);
This will create a text field that will hold a minimum of 10 characters. If the number of characters exceeds the display width of the text field the use can see the remaining characters by using the right/left arrow keys. That is the normal UI used by all applications I have ever seen. Don't try to create your own UI by using a horizontal scrollbar. Users are not accustomed to that.
for the text area you can create it using:
JTextArea textArea = new JTextArea(5, 30);
JScrollPane scrollPane = new JScrollPane( textArea );
to create a text area with 5 rows and approximately 30 character per row.
Now add the text field and the scrollpane to your frame "using layout managers" and then pack the frame. The layout managers will determine the best size for the compoents. Scrollbars will automatically appear on the text area as you add text to it and the text exceeds 5 lines.