Question

I have a custom renderer in a JTable. When my JTable displays, I get a NullPointerException on JTable.prepareRenderer(). I’m not sure what part of my custom renderer isn’t preparable, but I’m sure it’s my fault.

Condensed version of my renderer (full version at this spot):

public class GradeRenderer extends JLabel implements TableCellRenderer {    
    public Component getTableCellRendererComponent(JTable table, Object grade,
            boolean isSelected, boolean hasFocus, int row, int column) {
        if (grade == null) return new JLabel();
        Grade myself = (Grade) grade;
        int score = myself.getScore();
        setText(String.valueOf(score));
        Assessment thing = myself.getThing();
        GradeStatus status = myself.getStatus();
        AssessmentType type = thing.getType();
        // do some work with status
        // do some work with type
        return this;
    }
}

Code where I add the renderer (full version here):

model = new GradeEntryModel();
table = new JTable(model);
// some work with table
table.setDefaultRenderer(Grade.class, new GradeRenderer(true));

Any pointers as to where I’ve gone wrong?

Answer 1

Turns out some of my data in model is null. That’d do it.