java - JProgressBar in JTable not updating

Question

Why don't the progress bars in the following code update and how would I get them to?

import java.awt.event.{ActionListener, ActionEvent}
import javax.swing.table.{TableCellRenderer, AbstractTableModel}
import javax.swing.{Timer, JTable, JProgressBar, JFrame}

object TestProgressBar {
  val frame = new JFrame()
  val model = new TestModel()
  val table = new JTable(model)

  class TestModel extends AbstractTableModel {
    def getColumnCount = 4

    def getRowCount = 4

    def getValueAt(y: Int, x: Int) = "%d,%d".format(x, y)

    override def setValueAt(value: Any, row: Int, col: Int) {
      if (col == 0) {
        model.fireTableCellUpdated(row, col);
      }
    }
  }

  class TestCellRenderer extends TableCellRenderer with ActionListener {
    val progressBar = new JProgressBar()
    val timer = new Timer(100, this)

    progressBar.setIndeterminate(true)
    timer.start()

    override def getTableCellRendererComponent(tbl: JTable, value: AnyRef,
                                               isSelected: Boolean,
                                               hasFocus: Boolean,
                                               row: Int, column: Int) = {
      progressBar
    }

    override def actionPerformed(e: ActionEvent) {
      val model = table.getModel
      for (row <- 0 to model.getRowCount) {
        model.setValueAt(0, row, 0)
      }
    }
  }

  def main(args: Array[String]) {
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)

    table.getColumnModel.getColumn(0).setCellRenderer(new TestCellRenderer())

    frame.add(table)

    frame.pack()
    frame.setVisible(true)
  }
}

Answer 1

As @Robin notes, the renderer in only evoked when the model is updated. You need to periodically change the value in the desired row(s). This example uses javax.swing.Timer.

private class TestCellRenderer implements TableCellRenderer, ActionListener {

    JProgressBar bar = new JProgressBar();

    Timer timer = new Timer(100, this);

    public TestCellRenderer() {
        bar.setIndeterminate(true);
        timer.start();
    }

    @Override
    public Component getTableCellRendererComponent(JTable table,
        Object value, boolean isSelected, boolean hasFocus, int row, int column) {
        return bar;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        TableModel model = table.getModel();
        for (int row = 0; row < model.getRowCount(); row++) {
            table.getModel().setValueAt(0, row, 0);
        }
    }
}

You may also want to implement setValueAt(), as the AbstractTableModel implementation is empty:

@Override
public void setValueAt(Object aValue, int row, int col) {
    if (col == 1) {
        // update your internal model and notify listeners
        this.fireTableCellUpdated(row, col);
    }
}

Addendum: For reference, here's a corresponding Java implementation to complement the Scala.

Code:

import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.Timer;
import javax.swing.table.AbstractTableModel;
import javax.swing.table.TableCellRenderer;
import javax.swing.table.TableModel;

/**
* @see http://stackoverflow.com/a/10491290/230513
*/
public class TestProgressBar extends JPanel {

    private JTable table = new JTable(new TestModel());
    public TestProgressBar() {
        table.getColumnModel().getColumn(0).setCellRenderer(new TestCellRenderer());
        table.setPreferredScrollableViewportSize(new Dimension(320, 120));
        this.add(new JScrollPane(table));
    }

    private class TestModel extends AbstractTableModel {

        @Override
        public int getRowCount() {
            return 4;
        }

        @Override
        public int getColumnCount() {
            return 4;
        }

        @Override
        public Object getValueAt(int row, int col) {
            return String.valueOf(row) + ", " + String.valueOf(col);
        }

        @Override
        public void setValueAt(Object aValue, int row, int col) {
            // update internal model and notify listeners
            fireTableCellUpdated(row, col);
        }
    }

    private class TestCellRenderer implements TableCellRenderer, ActionListener {

        JProgressBar bar = new JProgressBar();
        Timer timer = new Timer(100, this);

        public TestCellRenderer() {
            bar.setIndeterminate(true);
            timer.start();
        }

        @Override
        public Component getTableCellRendererComponent(JTable table,
            Object value, boolean isSelected, boolean hasFocus, int row, int column) {
            return bar;
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            TableModel model = table.getModel();
            for (int row = 0; row < model.getRowCount(); row++) {
                table.getModel().setValueAt(0, row, 0);
            }
        }
    }

    private void display() {
        JFrame f = new JFrame("TestProgressBar");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(this);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

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

            @Override
            public void run() {
                new TestProgressBar().display();
            }
        });
    }
}