Re: Display image selected from JFileChooser

From:
Lew <noone@lewscanon.com>
Newsgroups:
comp.lang.java.programmer
Date:
Mon, 14 Jun 2010 08:00:35 -0400
Message-ID:
<hv55l0$9gg$1@news.albasani.net>
On 06/14/2010 04:22 AM, jimmy wrote:

Reply to Lew:

Many thanks for your comments on my code. Yes my statement "it doesn't
work" was vague and not informative, apologies. As you can tell I am a
Java novice and could not diagnose the faults myself. From your
comments it is clear that my code contained many problems. I will read
more about EDT and logger (I have left my println statements in for
the time being as I am more concerned with getting the images to
display at the moment).

reply to John B. Matthews:

Many thanks for your comments also. I have read and digested your
code, most of which I can follow, but some is still too advanced for
me. I have read the Action page you posted the link to and have tried
to implement an action in my code.

Heavily influenced by John B. Matthews' code, I have rewritten much of
my code, however it still does not display an image. I cannot identify
the source of the problem, but based on the println statements (which
I will remove in place of a logger) I think that myAction (the action
associated with the button) is not being returned.

I have attached my new code. I would be most grateful if someone could
identify the problem and indicate how I could resolve it.

....

import javax.imageio.ImageIO;


This is an unused import. Didn't your IDE warn you? Does your IDE support an
operation to clean up imports (Ctrl-Shift-O in Eclipse, Ctrl-Shift-I in NetBeans)?

class MyImage extends JPanel{

     private final Window parent;
     BufferedImage img;
     MyAction myAction = new MyAction();

     public MyImage(JFrame parent){
         this.parent = parent;
     }

     public void paintComponent(Graphics g) {
         super.paintComponent(g);
         g.drawImage(img, 0, 0, null);


'img' will always be 'null', since you never assign it a value.

     }

     public Action MyAction(){
         return myAction;
     }
}

import java.awt.event.ActionEvent;

class MyAction extends AbstractAction{

     BufferedImage image;

     public MyAction(){
         super("Open");
     }

     public void actionPerformed(ActionEvent e) {

         JFileChooser fileChooser = new JFileChooser();

         int returnVal = fileChooser.showOpenDialog(fileChooser);
         if (returnVal == JFileChooser.APPROVE_OPTION) {
             File file = fileChooser.getSelectedFile();
             System.out.println("Image selected: " + file.getPath());
             System.out.println("Image about to be loaded to buffer");
             try {
                 System.out.println("Image loaded to buffer");
                 image = ImageIO.read(fileChooser.getSelectedFile());


You create an image then throw it away. That is, if this line were to
compile, which it won't unless you import 'ImageIO'.

                 System.out.println("Image painted");


What in the world makes you think the image was painted here? All you did was
assign a variable. You never passed it to anything to paint anything.

             }
             catch (IOException ex) {
                 System.out.println("problem accessing
file"+file.getAbsolutePath());
             }
         }
         else {
             System.out.println("File access cancelled by user.");
         }
     }
}


--
Lew

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