New to Java

Hello.
I display some Double values represented as String in a JTable, but I want to align them RIGHT. Is there no easy way of doing this?

My structure is something like:

public class DataStructure extends AbstractTableModel {
  //Overrides standard methods
}

public class DataWindow {
  //Creates the JTable here
  JTable jt = new JTable(dataVectorVector,  columnNamesVector);

  // I have tried creating a custom tablecellrenderer, but error see below.
  CustomDataRenderer custom = new CustomDataRenderer();
  // and tries to implement it with. Fails, see below
  jt.getColumn(0).setCellRenderer(custom);
}

public class CustomDataRenderer extends DefaultTableCellRenderer {
  // This is copied in; I dont really understand it..:)
 public Component getTableCellRendererComponent( JTable jt ,Object value, boolean isSelected, 
						    boolean hasFocus, int row, int column) {
	System.out.println("i customhbvrenderer");
	Component comp = super.getTableCellRendererComponent(jt ,value,isSelected,hasFocus,row,column);
	JLabel label = (JLabel)comp;
	
	if(value.getClass().equals(new Double("2").getClass())){
	    label.setHorizontalAlignment(JLabel.RIGHT);
	}

	
	if( ((Double)value).isNaN() ) {
	    label.setBackground(Color.RED);
	}
	else {
	    label.setBackground(Color.WHITE);
	}
	return label;                   
    }
}

JWM breaks execusion with :

Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: Identifier not found
at javax.swing.table.DefaultTableColumnModel.getColumnIndex(Unknown Source)
at javax.swing.JTable.getColumn(Unknown Source)



Am I on the right track, and can anyone help me further?

Also: How can I verify an objects class? Referring to above, I would like to render cells with a Double inside one way, Strings other way etc, and need to check the class of the Objects.


Regards
JT