Graphics.drawImage NullPointerException with good image J2ME - java-me

Question

Display display = null;
String url = "http://188.2.222.253/screenshot.png";
DataInputStream is = null;
Image img= null;
try
{
HttpConnection c = (HttpConnection) Connector.open(url);
int len = (int)c.getLength();
if (len > 0)
{
is = c.openDataInputStream();
byte[] data = new byte[len];
is.readFully(data);
img = Image.createImage(data, 0, len);
Form f = new Form("Image");
GameCanvas gc = null;
Graphics g = null;
g.drawImage(img, 0, 0, 0); //NullPointerException
gc.paint(g);
display.setCurrent(gc);
}
else
{
showAlert("length is null");
}
is.close();
c.close();
}
catch (Exception e)
{
e.printStackTrace();
showAlert(e.getMessage());
}
g.drawImage(img, 0, 0, 0) throws NullPointerException. That means that img is null (http://docs.oracle.com/javame/config/cldc/ref-impl/midp2.0/jsr118/javax/microedition/lcdui/Graphics.html). I can use img with ImageItem and its NOT null. What is problem?

Answer 1

You are setting Graphics g = null just before you call g.drawImage(img, 0, 0, 0). It is not your img that is null. It is your Graphics object.
You're also setting GameCanvas gc = null 3 lines before you call gc.paint(g) - another NullPointerException.
On top of this, you can't create and draw on a GameCanvas using this approach. GameCanvas is an abstract class. So you need to create your own class which extends GameCanvas - if a GameCanvas is what you want. I'm not sure that's the case either, since you can easily settle for a Form, if all you want is to display a picture.
Try this instead:
img = Image.createImage(data, 0, len);
Form f = new Form("Image");
f.append(img);
display.setCurrent(f);