JSplitPane does not display items

Question

I am writing a tool take performs a task on text file. The task takes some time to perform so I made a panel that displays the file name and the progress in percentage. The user may run the task on one or on several files, so I need to display a panel for each file.
With help I got here I have this code which displays the text area and adds panels. The problem is that the textarea and the panel list both grow at the expense of each other when new items are added. You can see this happening when adding lines or clicking on the new button and adding panels:

import java.awt.event.*;
import javax.swing.*;
import java.util.*;
import java.util.logging.Logger;

public class FProgressDisplay extends JFrame {
    private final static Logger LOGGER = Logger.getLogger(FProgressDisplay.class.getName());
    private List<PanelTaskProgress> tasks;
    JTextArea txtLog;
    JButton btnNew;
    JButton btnAbort;
    JButton btnClose;
    static int i;
    JPanel taskPanel;

    public static void main(String[] args) {
        try {
            FProgressDisplay frame = new FProgressDisplay();
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setVisible(true);

        } catch (Exception e) {
            e.printStackTrace();
            throw new RuntimeException("Failed to initialize application.");
        }
    }
    /**
     * Create the frame.
     */
    public FProgressDisplay() {
        setTitle("Mask tool - Progress");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        // should be done AFTER components are added
        //pack();
        getContentPane().setLayout(new BoxLayout(getContentPane(), BoxLayout.Y_AXIS));
        taskPanel = new JPanel();
        taskPanel.setLayout(new BoxLayout(taskPanel, BoxLayout.Y_AXIS));

        JPanel panel = new JPanel();
        getContentPane().add(panel);

        btnNew = new JButton("New");
        panel.add(btnNew);
        btnNew.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent ae) {
                addTask(++i, "Task " + i);
            }
        });

        btnAbort = new JButton("Abort");
        panel.add(btnAbort);

        btnClose = new JButton("Close");
        panel.add(btnClose);

        txtLog = new JTextArea(10,0);
        txtLog.setLineWrap(true);
        getContentPane().add(txtLog);

        tasks = new ArrayList<PanelTaskProgress>();

        JScrollPane scrollPane = new JScrollPane(taskPanel);
        getContentPane().add(scrollPane);

        for(i = 0; i < 10; i++) {
            addTask(i, "Task"+i);
        }
        pack();
    }

    public void addTask(long id, String fileName) {
        PanelTaskProgress newTaskPanel = new PanelTaskProgress(id, fileName);
        tasks.add(newTaskPanel);
        taskPanel.add(newTaskPanel);
        validate();
        //repaint();
        LOGGER.info("Added new panel");
    }

    public class PanelTaskProgress extends JPanel {
        private static final long serialVersionUID = 1L;
        JLabel lblTaskDescription;
        JLabel lblProgress;
        private long id;
        /**
         * Create the panel.
         */
        public PanelTaskProgress(long id, String fileName) {
            try {
                //setLayout(null);

                lblTaskDescription = new JLabel(id + " " + fileName);
                //lblTaskDescription.setPreferredSize(new Dimension(632, 14));
                add(lblTaskDescription);

                lblProgress = new JLabel("0%");
                lblProgress.setHorizontalAlignment(SwingConstants.CENTER);
                //lblProgress.setBounds(664, 11, 51, 14);
                add(lblProgress);

                LOGGER.info("Created new panel; Id: " + id + "; File: " + fileName);
            } catch (Exception e) {
                LOGGER.severe("Error creating new panel; " + e.getMessage());
            }
        }
    }
}

I want each to remain in its own area and add scroll if needed. I tried to add a JSplitPane to the example above, but both panes remain empty.

import java.awt.event.*;
import javax.swing.*;
import javax.swing.plaf.SplitPaneUI;

import java.util.*;
import java.util.logging.Logger;

public class FProgressDisplay extends JFrame {
    private final static Logger LOGGER = Logger
            .getLogger(FProgressDisplay.class.getName());
    private List<PanelTaskProgress> tasks;
    JTextArea txtLog;
    JButton btnNew;
    JButton btnAbort;
    JButton btnClose;
    static int i;
    JPanel taskPanel;

    private JSplitPane splitPane;

    public static void main(String[] args) {
        try {
            FProgressDisplay frame = new FProgressDisplay();
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setVisible(true);

        } catch (Exception e) {
            e.printStackTrace();
            throw new RuntimeException("Failed to initialize application.");
        }
    }

    /**
     * Create the frame.
     */
    public FProgressDisplay() {
        setTitle("Mask tool - Progress");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        // should be done AFTER components are added
        // pack();
        getContentPane().setLayout(
                new BoxLayout(getContentPane(), BoxLayout.Y_AXIS));
        taskPanel = new JPanel();
        taskPanel.setLayout(new BoxLayout(taskPanel, BoxLayout.Y_AXIS));

        JPanel panel = new JPanel();
        getContentPane().add(panel);

        btnNew = new JButton("New");
        panel.add(btnNew);
        btnNew.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent ae) {
                addTask(++i, "Task " + i);
            }
        });

        btnAbort = new JButton("Abort");
        panel.add(btnAbort);

        btnClose = new JButton("Close");
        panel.add(btnClose);

        txtLog = new JTextArea(10, 0);
        txtLog.setLineWrap(true);
        //getContentPane().add(txtLog);

        tasks = new ArrayList<PanelTaskProgress>();

        JScrollPane scrollPane = new JScrollPane(taskPanel);
        //getContentPane().add(scrollPane);
        splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT, txtLog, scrollPane);
        splitPane.setDividerLocation(150);

        for (i = 0; i < 10; i++) {
            addTask(i, "Task" + i);
        }
        pack();
    }

    public void addTask(long id, String fileName) {
        PanelTaskProgress newTaskPanel = new PanelTaskProgress(id, fileName);
        tasks.add(newTaskPanel);
        taskPanel.add(newTaskPanel);
        validate();
        // repaint();
        LOGGER.info("Added new panel");
    }

    public class PanelTaskProgress extends JPanel {
        private static final long serialVersionUID = 1L;
        JLabel lblTaskDescription;
        JLabel lblProgress;
        private long id;

        /**
         * Create the panel.
         */
        public PanelTaskProgress(long id, String fileName) {
            try {
                // setLayout(null);

                lblTaskDescription = new JLabel(id + " " + fileName);
                // lblTaskDescription.setPreferredSize(new Dimension(632, 14));
                add(lblTaskDescription);

                lblProgress = new JLabel("0%");
                lblProgress.setHorizontalAlignment(SwingConstants.CENTER);
                // lblProgress.setBounds(664, 11, 51, 14);
                add(lblProgress);

                LOGGER.info("Created new panel; Id: " + id + "; File: "
                        + fileName);
            } catch (Exception e) {
                LOGGER.severe("Error creating new panel; " + e.getMessage());
            }
        }
    }
}

Here is the solution:

package layout.sscce;

import java.awt.BorderLayout;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
import java.util.logging.Logger;

public class FProgressDisplay extends JFrame {
    private final static Logger LOGGER = Logger
            .getLogger(FProgressDisplay.class.getName());
    private List<PanelTaskProgress> tasks;
    JTextArea txtLog;
    JButton btnNew;
    JButton btnAbort;
    JButton btnClose;
    static int i;
    JPanel taskPanel;

    private JSplitPane splitPane;

    public static void main(String[] args) {
        try {
            FProgressDisplay frame = new FProgressDisplay();
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setVisible(true);

        } catch (Exception e) {
            e.printStackTrace();
            throw new RuntimeException("Failed to initialize application.");
        }
    }

    /**
     * Create the frame.
     */
    public FProgressDisplay() {
        setTitle("Mask tool - Progress");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        // should be done AFTER components are added
        // pack();
//        getContentPane().setLayout(
//                new BoxLayout(getContentPane(), BoxLayout.Y_AXIS));
        getContentPane().setLayout(
                new BorderLayout());

        taskPanel = new JPanel();
        taskPanel.setLayout(new BoxLayout(taskPanel, BoxLayout.Y_AXIS));

        JPanel buttonPanel = new JPanel();
        getContentPane().add(buttonPanel);

        btnNew = new JButton("New");
        buttonPanel.add(btnNew);
        btnNew.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent ae) {
                addTask(++i, "Task " + i);
            }
        });

        btnAbort = new JButton("Abort");
        buttonPanel.add(btnAbort);

        btnClose = new JButton("Close");
        buttonPanel.add(btnClose);

        txtLog = new JTextArea(10, 30);
        txtLog.setLineWrap(true);
        //getContentPane().add(txtLog);

        tasks = new ArrayList<PanelTaskProgress>();

        JScrollPane taskScrollPane = new JScrollPane(taskPanel);
        JScrollPane textScrollPane = new JScrollPane(txtLog);

        splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT, textScrollPane, taskScrollPane);
        splitPane.setDividerLocation(150);

        for (i = 0; i < 10; i++) {
            addTask(i, "Task" + i);
        }



        getContentPane().add(buttonPanel, BorderLayout.NORTH);
        getContentPane().add(splitPane, BorderLayout.CENTER);

        pack();
    }

    public void addTask(long id, String fileName) {
        PanelTaskProgress newTaskPanel = new PanelTaskProgress(id, fileName);
        tasks.add(newTaskPanel);
        taskPanel.add(newTaskPanel);
        validate();
        // repaint();
        LOGGER.info("Added new panel");
    }

    public class PanelTaskProgress extends JPanel {
        private static final long serialVersionUID = 1L;
        JLabel lblTaskDescription;
        JLabel lblProgress;
        private long id;

        /**
         * Create the panel.
         */
        public PanelTaskProgress(long id, String fileName) {
            try {
                // setLayout(null);

                lblTaskDescription = new JLabel(id + " " + fileName);
                // lblTaskDescription.setPreferredSize(new Dimension(632, 14));
                add(lblTaskDescription);

                lblProgress = new JLabel("0%");
                lblProgress.setHorizontalAlignment(SwingConstants.CENTER);
                // lblProgress.setBounds(664, 11, 51, 14);
                add(lblProgress);

                LOGGER.info("Created new panel; Id: " + id + "; File: "
                        + fileName);
            } catch (Exception e) {
                LOGGER.severe("Error creating new panel; " + e.getMessage());
            }
        }
    }
}

Answer 1

The problem is the BoxLayout. It does wierd things as it tries to allocate the space between components. Maybe a BorderLayout would be better. Add the buttons to the NORTH and the scrollPane to the CENTER.

Or using your code you can do the following:

        txtLog = new JTextArea(10, 30); // changed
        txtLog.setLineWrap(true);
        getContentPane().add(txtLog);

        tasks = new ArrayList<PanelTaskProgress>();

        JScrollPane scrollPane = new JScrollPane(taskPanel);
        scrollPane.setPreferredSize( txtLog.getPreferredSize() ); // added