JPanel fatPanel   = new JPanel();
  JPanel calPanel   = new JPanel();
  JPanel perPanel   = new JPanel();
  
  public percentFatPanel()   
  {  
    fatPanel.add( fatLabel );
    fatPanel.add( inFat );
    calPanel.add( calLabel );
    calPanel.add( inCal );
    perPanel.add( perLabel );
    perPanel.add( outPer );

BoxLayout Layout Manager

Now the three panels are added to the content pane. We want the label, the panels, and the button to be lined up in a vertical column. FlowLayout would do this if the frame is not too wide. But we want it to always be the case. For this, use BoxLayout. BoxLayout puts components in either a vertical column or a horizontal row. Say which arrangement you want in its constructor:

BoxLayout(Container target, int axis) 

    target: the container this layout manager is for
            
    axis: BoxLayout.X_AXIS for left to right
          BoxLayout.Y_AXIS for top to bottom

The target field is a reference to the container (normally the conent pane) which the new layout manager is for.

public class percentFatPan extends JFrame 
  implements ActionListener
{

  
  public percentFatPanel()   
  {  
    getContentPane().setLayout( 
        new BoxLayout( ________, ________ );  
   . . . . .