Table Row Rendering

There are times when you might want to do some custom rendering for an entire row of a table. Based on answers I see in the forums, for most people the first thought is to create a custom renderer. This can be a simple solution in some cases, but are there other alternatives to consider as well?

A renderer is used by a JTable to render a class of data for a given column. So when all the data in the table is of the same class, String for example, then the easiest solution is probably to create a custom String renderer containing your custom row rendering logic.

However, what happens when your table contains multiple classes of data, maybe String, Date, Integer and Boolean? Would you create 4 custom renderers or is there a better way?

In this situation it is possible to write the custom rendering code only once and have it applied to all renderers. The trick is to override the prepareRenderer(…) method of JTable. This method is invoked every time a cell is rendered so it is the perfect place to add row level rendering logic that can be applied to all renderers.

A simple example for overriding this method would be as follows:

JTable table = new JTable(...)
{
    public Component prepareRenderer(
        TableCellRenderer renderer, int row, int column)
    {
        Component c = super.prepareRenderer(renderer, row, column);

        //  Alternate row color 

        if (!isRowSelected(row))
            c.setBackground(row % 2 == 0 ? getBackground() : Color.LIGHT_GRAY);

        return c;
    }
};

 You can use this technique to alternate the background color of each row:

… add a row level Border:

… change the background color based on data in the row:

Although this tip was suggested to be used for row rendering. It can be considered any time you want to add common logic to multiple different renderers.

Get The Code

TableRowRenderingTip.java

Related Reading

Java Tutorials: Concepts – Editor and Renderers