Re: newbie:this program gives error on compiling

From:

Roedy Green <see_website@mindprod.com.invalid>

Newsgroups:

comp.lang.java.help

Date:

Sun, 23 Dec 2007 04:27:37 GMT

Message-ID:

<0fkrm39q5a6s4csa0msmrh9o8pggbki83s@4ax.com>

Here is how to make it easier for others to help:

Display the listing like this with the error messages embedded:

public class OvalButton extends JButton
   {

   public OvalButton(String text)
      {
      super(text);
      setOpaque(false);
      }
   public Shape getShape()
      {
      return new Ellipse2D.Float(0,0,getWidth()/2,getHeight());

-----------------------------------------------------------------------------------
ERROR
OvalButton.java:16: package Ellipse2D does not exist
      return new Ellipse2D.Float(0,0,getWidth()/2,getHeight());
                          ^
-----------------------------------------------------------------------------------
COMMENTARY
For some reason Javac thinks Ellipse is a package that Float lives.
Packages always start with a lower case letter so a red flag goes up.
Float is an inner class of Ellipse2D. It has a constructor
Ellipse2D.Float(float x, float y, float w, float h)

I like to import classes explicitly, rather than using * notation,
e.g.
import java.awt.geom.Ellipse2D;
import java.awt.geom.Ellipse2D.Float;

When I did that he error went away.

You could also do just:
import java.awt.geom.Ellipse2D;
or
import java.awt.geom.*;
Since inner classes are imported automatically.

I like to use IntelliJ or other IDE to tidy the imports. It does a
much better job than you can manually.

The easy way to solve this is to look the error message up at
http://mindprod.com/jgloss/compileerrormessages.html#PACKAGEDOESNTEXIST
-----------------------------------------------------------------------------------
      }
   public void paint(Graphics g)
      {
      Graphics2D g2=(Graphics2D) g;
      g2.getClip(getShape());
-----------------------------------------------------------------------------------
ERROR
OvalButton.java:21: getClip() in java.awt.Graphics cannot be applied
to (java.awt.Shape)
      g2.getClip(getShape());
        ^
-----------------------------------------------------------------------------------
COMMENTARY
I could not find a method Graphics2.getClip( Shape), just inherited
Graphics.getClip(). One of the first things to do is check the
Javadoc to make sure there is a method with the signature you think
SHOULD be there.

The easy way to solve this is to look the error message up at
http://mindprod.com/jgloss/compileerrormessages.html#CANTBEAPPLIED
-----------------------------------------------------------------------------------
      super.paint(g2);
      }
   public boolean contains(int x,int y)
      {
      return getShape().contains(x,y);
      }
   }

--
Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com