import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import javax.swing.JComponent;

/**
   A component that shows a colored square.
*/
public class ColoredSquareComponent extends JComponent
{  
   /**
      Constructs a component that shows a colored square.
      @param aColor the fill color for the square
   */
   public ColoredSquareComponent(Color aColor)
   {  
      fillColor = aColor;
   }
   
   public void paintComponent(Graphics g)
   {  
      Graphics2D g2 = (Graphics2D) g;

      // Select color into graphics context
   
      g2.setColor(fillColor);
      
      // Construct and fill a square whose center is
      // the center of the window

      final int SQUARE_LENGTH = 100;
      
      Rectangle square = new Rectangle(
            (getWidth() - SQUARE_LENGTH) / 2,
            (getHeight() - SQUARE_LENGTH) / 2,
            SQUARE_LENGTH,
            SQUARE_LENGTH);
         
      g2.fill(square);
   }
   
   private Color fillColor;
}