Question

I have a ScrollPane and JTable that should only have one row of data.

String[] daysOfWeek = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
        String[][] data = {{"None","None","None","None","None","None","None"}};

        JTable mTable = new JTable(data, daysOfWeek);

        JScrollPane scrollPane = new JScrollPane(mTable);
        mTable.setFillsViewportHeight(false);

I want the ScrollPane to fit around the borders of the table but at the moment the height of the Scrollpane takes up the entirety of the container, making it look really ugly. I don’t understand why, since I set mTable.setFillsViewportHeight(false).

Any help how to achieve a ScrollPane that doesn’t stretch beyond the size of the table would be welcome.

Answer 1

you can use table.setPreferredScrollableViewportSize(table.getPreferredSize());

edit

import java.awt.*;
import java.awt.event.ActionEvent;
import java.util.Random;
import java.util.concurrent.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.DefaultTableModel;

public class ChangeNotifiersOnEvent extends JFrame implements Runnable {

    private static final long serialVersionUID = 1L;
    private boolean runProcess = true;
    private Random random = new Random();
    private javax.swing.Timer timerRun;
    private Executor executor = Executors.newCachedThreadPool();
    private String[] columnNames = {"Source", "Hit", "Last", "Ur_Diff"};
    private JTable table;
    private Object[][] data = {{"Swing Timer", 2.99, 5, 1.01},
        {"Swing Worker", 7.10, 5, 1.010}, {"TableModelListener", 25.05, 5, 1.01}};
    private DefaultTableModel model = new DefaultTableModel(data, columnNames);

    public ChangeNotifiersOnEvent() {
        table = new JTable(model) {

            private static final long serialVersionUID = 1L;

            @Override
            public Class getColumnClass(int column) {
                return getValueAt(0, column).getClass();
            }
        };
        model.addTableModelListener(new TableModelListener() {

            @Override
            public void tableChanged(TableModelEvent tme) {
                if (tme.getType() == TableModelEvent.UPDATE) {
                    if (tme.getColumn() == 1 && tme.getLastRow() == 2) {
                        double dbl = ((Double) table.getModel().getValueAt(2, 1))
                                - ((Integer) table.getModel().getValueAt(2, 2));
                        table.getModel().setValueAt(dbl, 2, 3);
                    } else if (tme.getColumn() == 1 && tme.getLastRow() == 0) {
                        prepareUpdateTableCell();
                    } else if (tme.getColumn() == 1 && tme.getLastRow() == 1) {
                        executor.execute(new MyTask(MyTask.UPDATE_TABLE_COLUMN));
                    }
                }
            }
        });
        table.setRowHeight(30);
        table.setFont(new Font("Serif", Font.BOLD, 20));
        table.getColumnModel().getColumn(0).setPreferredWidth(180);
        table.setPreferredScrollableViewportSize(table.getPreferredSize());
        JScrollPane scrollPane = new JScrollPane(table);
        add(scrollPane, BorderLayout.CENTER);
        new Thread(this).start();
    }

    private void prepareUpdateTableCell() {
        timerRun = new javax.swing.Timer(10, UpdateTableCell());
        timerRun.setRepeats(false);
        timerRun.start();
    }

    private Action UpdateTableCell() {
        return new AbstractAction("Update Table Cell") {

            private static final long serialVersionUID = 1L;

            @Override
            public void actionPerformed(ActionEvent e) {
                double dbl = ((Double) table.getModel().getValueAt(0, 1))
                        - ((Integer) table.getModel().getValueAt(0, 2));
                table.getModel().setValueAt(dbl, 0, 3);
            }
        };
    }

    @Override
    public void run() {
        while (runProcess) {
            try {
                Thread.sleep(330);
            } catch (Exception e) {
                e.printStackTrace();
            }
            changeTableValues();
        }
    }

    private void changeTableValues() {
        Runnable doRun = new Runnable() {

            @Override
            public void run() {
                table.getModel().setValueAt(random.nextInt(128) + random.nextDouble(), 0, 1);
                table.getModel().setValueAt(random.nextInt(256) + random.nextDouble(), 1, 1);
                table.getModel().setValueAt(random.nextInt(512) + random.nextDouble(), 2, 1);

                table.getModel().setValueAt(random.nextInt(128), 0, 2);
                table.getModel().setValueAt(random.nextInt(128), 1, 2);
                table.getModel().setValueAt(random.nextInt(128), 2, 2);
            }
        };
        SwingUtilities.invokeLater(doRun);
    }

    private class MyTask extends SwingWorker<Void, Integer> {

        private static final String UPDATE_TABLE_COLUMN = "update";
        private String namePr;
        private double dbl;

        MyTask(String str) {
            this.namePr = str;
        }

        @Override
        protected Void doInBackground() throws Exception {
            dbl = ((Double) table.getModel().getValueAt(1, 1))
                    - ((Integer) table.getModel().getValueAt(1, 2));
            return null;
        }

        @Override
        protected void done() {
            SwingUtilities.invokeLater(new Runnable() {

                @Override
                public void run() {
                    table.getModel().setValueAt(dbl, 1, 3);
                }
            });
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                ChangeNotifiersOnEvent frame = new ChangeNotifiersOnEvent();
                frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
                frame.setLocation(150, 150);
                frame.pack();
                frame.setVisible(true);
            }
        });
    }
}