Re: JScrollPane Scrollbar issues

Michael,

  I saw what you meant. Sorry for the sloppy code. Here is another
version more tightly coupled to my code. The only difference is that I
removed the validate() call from my code and it still displays the same
way. If you click the update button at the bottom of the window, watch
the scrollbars, they jump to the middle and stay there. My GUI loads
that way, which is odd to me because I removed the validate() call.

import java.awt.Dimension;
import javax.swing.*;
import javax.swing.border.*;

import java.awt.*;
import java.awt.event.*;

public class Test {

    public static final void main( String args[] ) {

        Box displayPane = new Box(BoxLayout.PAGE_AXIS);
        Dimension d = new Dimension(500,500);
        int idx = 0;
        TestPanel viewport = new TestPanel(idx);
        displayPane.add(viewport);

        JButton update = new JButton("update");
        update.addActionListener(viewport);
        displayPane.add(update);
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation( JFrame.DISPOSE_ON_CLOSE );
        frame.setContentPane( displayPane );
        frame.pack();
        frame.setVisible(true);
    }
}
// Creates the ViewPort panel
class TestPanel extends JPanel implements ActionListener {

    Dimension dfltSize = new Dimension(400, 150);
    int offset = 36;
    int og;
    Dimension d = new Dimension(1200, 225);
    Dimension vpSize = new Dimension(500,500);
    JScrollPane scrollPane;
    JPanel viewport;

    public TestPanel(int idx) {
        og = idx+1;
        scrollPane = new
JScrollPane(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
        viewport = createPanel(idx);
        add(scrollPane);
        scrollPane.setPreferredSize(vpSize);
        scrollPane.setMaximumSize(vpSize);
        scrollPane.setMinimumSize(vpSize);
        scrollPane.setViewportView(viewport);
        scrollPane.validate();
    }

    public JPanel createPanel(int idx){
        JPanel view = new JPanel();
        view.setLayout(new GridLayout(0, 6));
        for (int i = idx; i < idx+offset; i++) {
            // add new repeated panels
            RepeatedPanel tmp = new RepeatedPanel(i);
            tmp.setPreferredSize(dfltSize);
            tmp.setMaximumSize(dfltSize);
            tmp.setMinimumSize(dfltSize);
            view.add(new RepeatedPanel(i));
        }
        return view;
    }

    public void actionPerformed(ActionEvent e) {
     update();
    }
    public void update(){
        viewport = createPanel(og++);
        scrollPane.setViewportView(viewport);
        scrollPane.validate();
    }
}

class RepeatedPanel extends JPanel {
    JTextField singleLine1;
    JTextField singleLine2;
    JTextArea multiLine;
    Border txtAreaBorder;
    Dimension txtAreaSize = new Dimension(100, 100);

    public RepeatedPanel(int idx) {
        singleLine1 = new JTextField(Integer.toString(idx));
        add(singleLine1);

        singleLine2 = new JTextField(Integer.toString(idx));
        add(singleLine2);

        multiLine = new JTextArea(Integer.toString(idx));
        multiLine.setLineWrap(true);
        multiLine.setPreferredSize(txtAreaSize);
        multiLine.setMaximumSize(txtAreaSize);
        multiLine.setMinimumSize(txtAreaSize);
        add(multiLine);

        setBorder(BorderFactory.createLoweredBevelBorder());
    }
}