Question

I’m working with the following code that contains a JProgressBar inside of an AbstractTableModel. The JProgressBar progress value is updated in “case 5: ” of the getValueAt() function by returning a Float. What I’m trying to figure out is how to access the underlying JProgressBar instance so I can modify some of it’s properties other than the progress value (such as setVisible()).

package org.jdamico.jhu.runtime;

import java.util.*;
import javax.swing.*;
import javax.swing.table.*;

// This class manages the upload table's data.
class TransfersTableModel extends AbstractTableModel implements Observer {

    /**
     * 
     */
    private static final long serialVersionUID = 2740117506937325535L;

    // These are the names for the table's columns.
    private static final String[] columnNames = { "Type","Name", "UUID","Status",
            "Stage","Progress","Total Start Time","Total End Time" };

    // These are the classes for each column's values.
    private static final Class[] columnClasses = { String.class,String.class,String.class, 
            String.class,String.class, JProgressBar.class, String.class, String.class};

    // The table's list of uploads.
    private ArrayList<ParentEntry> transferList = new ArrayList<ParentEntry>();

    // Add a new upload to the table.
    public void addTransfer(ParentEntry pe) {

        // Register to be notified when the upload changes.
        pe.addObserver(this);

        transferList.add(pe);

        // Fire table row insertion notification to table.
        fireTableRowsInserted(getRowCount(), getRowCount());
    }

    // Get a upload for the specified row.
    public ParentEntry getTransfer(int row) {
        return transferList.get(row);
    }

    // Remove a upload from the list.
    public void clearTransfer(int row) {
        transferList.remove(row);

        // Fire table row deletion notification to table.
        fireTableRowsDeleted(row, row);
    }

    // Get table's column count.
    public int getColumnCount() {
        return columnNames.length;
    }

    // Get a column's name.
    public String getColumnName(int col) {
        return columnNames[col];
    }

    // Get a column's class.
    public Class getColumnClass(int col) {
        return columnClasses[col];
    }

    // Get table's row count.
    public int getRowCount() {
        return transferList.size();
    }

    // Get value for a specific row and column combination.
    public Object getValueAt(int row, int col) {

        ParentEntry pe = transferList.get(row);
        switch (col) {
        case 0:
            return pe.getType();
        case 1: // URL
            return pe.getUrl();
        case 2: //UUID
            return pe.getUUID() + "";
        case 3: // Status
            return pe.getStatus().getDisplay();
        case 4: // Stage
            return pe.getStage().getDisplay();
        case 5: //Progress
            return new Float(pe.getProgress());
        case 6:
            if (pe.getTotalStartTime() != null)
                return pe.getTotalStartTime().getTime().toString();
            else
                return "";
        case 7:
            if (pe.getTotalEndTime() != null)
                return pe.getTotalEndTime().getTime().toString();
            else
                return "";
        }
        return "";
    }

    /*
     * Update is called when a Upload notifies its observers of any changes
     */
    public void update(Observable o, Object arg) {
        int index = transferList.indexOf(o);

        // Fire table row update notification to table.
        fireTableRowsUpdated(index, index);
    }
}

Update: This wasn’t originally my code and I’m still familiarizing myself with it, but I just discovered that there was a ProgressRenderer class that extends JProgressBar and implements TableCellRenderer. This is what is being used to render the progress bar in the table. So I’m going to alter this code to alter how the progress bar is being displayed:

package org.jdamico.jhu.runtime;

import java.awt.*;
import javax.swing.*;
import javax.swing.table.*;

/*import org.jdamico.jhu.components.Controller;
import org.jdamico.jhu.components.FilePartition;
import org.vikulin.utils.Constants;*/

// This class renders a JProgressBar in a table cell.
class ProgressRenderer extends JProgressBar implements TableCellRenderer {




    // Constructor for ProgressRenderer.
    public ProgressRenderer(int min, int max) {
        super(min, max);
    }

    /*
     * Returns this JProgressBar as the renderer for the given table cell.
     */
    public Component getTableCellRendererComponent(JTable table, Object value,
            boolean isSelected, boolean hasFocus, int row, int column) {
        // Set JProgressBar's percent complete value.
        Float tmp = ((Float) value).floatValue();
        if (tmp == -1) {
            this.setVisible(false);
        }
        else {
            setValue((int) ((Float) value).floatValue());
            if (this.isVisible() == false)
                this.setVisible(true);
        }
        return this;
    }



}

Answer 1

You could add a method to the class that allows you to get the JProgressBar associated with the row of interest, something like:

   public JProgressBar getProgressBar(int row) {
      ParentEntry pe = transferList.get(row);
      return pe.getProgress();
   }

It seems kind of funny to me that the model would hold a JProgressBar rather than a simple int representing percentage complete. It would make more sense to me to have any code for progress bar display be in the JTable’s cell renderer.

Edit 1
In reply to opike’s comment below:

Does it really make the code that much more efficient to use the JProgressBar outside of the model vs inside of it? Is the gain enough so to expend time rewriting the code? The existing code works the way I need it to for the most part so I would prefer just tweaking it vs a more significant rewrite.

My question and my concern is, is your cell renderer using the JProgressBar held by the model? If so, how can it if there is no way for it to obtain the JProgressBar? If it’s only using the Float value obtained, it simply makes no sense for the model to hold information and resources that are not used. And yes, this could slow your program down noticeably.