New frames vs. resetting documents

Question

Hi everybody,
I'm fairly certain this is a conceptual thing I'm not getting--if I'm wrong, I'd be glad to post a SSCCE with my problem in it. But anyway, here goes, hopefully, I'm right about it being a conceptual thing. I have a JTextPane inside a JScrollPane, and when I hit a button, the JTextPane refreshes with new text. The only way I can get the JScrollPane to work with the current text, and not the text the pane was initialized to, is to make a new JFrame every time I hit that button. Now, what it seems is happening to me is that calling a new JFrame wipes out all the memory and allows the new data to work, and there must be some sort of memory that stays around if I don't do that. Am I right, conceptually, that creating the new JFrame is the only way to completely erase the JTextPane, and resetting documents doesn't actually erase it?
Thanks,
Jezzica85

Answer 1

Hi everybody,
Thanks for trying to help so far; here's my SSCCE. I know that there are problems with incrementing in the page buttons; that's just a function of the test program--it works fine in my real program, but the real issue, how the text pane doesn't stay right at scrolling, is still intact. If anyone could help me figure this out with the SSCCE, I'd really appreciate it.
Thanks again,
Jezzica85
PS-- Oh, I forgot to say, I know it looks like my second argument to "display" doesn't do anything; it does something in my real program, and it just isn't necessary for the test. I didn't want to change the method signature, just in case.
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextPane;
import javax.swing.text.StyledDocument;
public class Test {
     // need a 2D String array for input; usually I have it from an input file
     // but for the test this should be OK
     private static String[][] array = {
          { "test1", "test1b", "test1c", "test1d", "test1", "test1b", "test1c", "test1d", "test1", "test1b", "test1c", "test1d", "test1", "test1b", "test1c", "test1d", },
          { "test2", "test2b", "test2c", "test2d", "test2", "test2b", "test2c", "test2d", "test2", "test2b", "test2c", "test2d", "test2", "test2b", "test2c", "test2d", },
          { "test3", "test3b", "test3c", "test3d", "test3", "test3b", "test3c", "test3d", "test3", "test3b", "test3c", "test3d", "test3", "test3b", "test3c", "test3d", }
     private static int previous, next;
     public static void main(String[] args) {
          display( new JFrame(), "", array[0], 1 );
     private static void display( JFrame frame, String type, String[] lines, Integer page ) {
          try {
               final JFrame frameCopy = frame;
               JPanel panel = new JPanel( new GridLayout( 0, 2 ) );
               String[] buttons = { "Previous Page", "Next Page" };
               for( int i = 0; i < 2; i++ ) {
                    JButton button = new JButton( buttons[i] );
                    if( i == 0 ) {
                         previous = page - 1;
                         button.addActionListener( new ActionListener() {
                              public void actionPerformed( ActionEvent e ) {
                                   display( frameCopy, "", array[previous], previous );
                    } else {
                         next = page + 1;
                         button.addActionListener( new ActionListener() {
                              public void actionPerformed( ActionEvent e ) {
                                   display( frameCopy, "", array[next], next );
                    panel.add( button );
               frame.add( panel, BorderLayout.NORTH );
               // Populate document
               JTextPane pane = new JTextPane();
               StyledDocument doc = pane.getStyledDocument();
               for( String element: lines ) {
                    doc.insertString( doc.getLength(), element + "\n", null );
               doc.remove( doc.getLength() - 1, 1 );
               pane.setDocument( doc );
               pane.setCaretPosition( 0 );
               JScrollPane scroller = new JScrollPane( pane );
               scroller.setVerticalScrollBarPolicy( JScrollPane.VERTICAL_SCROLLBAR_ALWAYS );
               frame.add( scroller );
               frame.setSize( 770, 150 );
               frame.setLocationRelativeTo( null );
               frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
               frame.setVisible( true );
          } catch( Exception e ) {
               e.printStackTrace();
               System.exit( -1 );
}