listfield with bitmap loaded from server - blackberry

Question

i have made a listfield with images, the listfield is parsed from online xml file.
it seems that downloading the images into the listfield is blocking the process of parsing the content of the listfield "text" , i want to show the content of the listfield "text" and then start to proccess the download of the images and then show the images.
here is the code to call the downloader class:
Thread t = new Thread();
{
String imageFilename = imageurlStrin.substring(imageurlStrin.lastIndexOf('/') + 1);
String saveDire = "file:///store/home/user/pictures/listfield/"+imageFilename;
try {
FileConnection fconn = (FileConnection)Connector.open(saveDire);
if (fconn.exists()) {
// do nothing
}
if (!fconn.exists()) {
UrlToImage bit = new UrlToImage(imageurlStrin);
pic = bit.getbitmap();
}
}catch (Exception ioe) {
System.out.println("error 18");
}
};
t.start();
and this is the downloader class code:
public class UrlToImage implements Runnable{
String imageurlStrin=null;
BitmapDowloadListener listener=null;
public static Bitmap _bmap;
private EncodedImage eih1;
public void run() {
UrlToImage bit = new UrlToImage(imageurlStrin);
}
public UrlToImage(String imageurlStrin)
{
HttpConnection connection = null;
InputStream inputStream = null;
EncodedImage bitmap;
byte[] dataArray = null;
//byte[] data1 = null;
try
{
connection = (HttpConnection) Connector.open(imageurlStrin, Connector.READ, true);
inputStream = connection.openInputStream();
byte[] responseData = new byte[10000];
int length = 0;
StringBuffer rawResponse = new StringBuffer();
while (-1 != (length = inputStream.read(responseData)))
{
rawResponse.append(new String(responseData, 0, length));
}
int responseCode = connection.getResponseCode();
if (responseCode != HttpConnection.HTTP_OK)
{
throw new IOException("HTTP response code: "
+ responseCode);
}
final String result = rawResponse.toString();
dataArray = result.getBytes();
}
catch (final Exception ex)
{ }
finally
{
try
{
inputStream.close();
inputStream = null;
connection.close();
connection = null;
}
catch(Exception e){}
}
bitmap = EncodedImage.createEncodedImage(dataArray, 0,dataArray.length);
// this will scale your image acc. to your height and width of bitmapfield
int multH;
int multW;
int currHeight = bitmap.getHeight();
int currWidth = bitmap.getWidth();
int scrhi = Display.getWidth()/4;
int scrwe = Display.getWidth()/4;
multH= Fixed32.div(Fixed32.toFP(currHeight),Fixed32.toFP(scrhi));//height
multW = Fixed32.div(Fixed32.toFP(currWidth),Fixed32.toFP(scrwe));//width
bitmap = bitmap.scaleImage32(multW,multH);
Bitmap thefinal = bitmap.getBitmap();
//url = StringUtils.replaceAll(url ,"http://u.bbstars.com/i-", "");
final String imageFilename = imageurlStrin.substring(imageurlStrin.lastIndexOf('/') + 1);
String saveDire = "file:///store/home/user/pictures/listfield/"+imageFilename;
String Dire = "file:///store/home/user/pictures/listfield/";
JPEGEncodedImage finalJPEG = JPEGEncodedImage.encode(thefinal, 100);
byte[] raw_media_bytes = finalJPEG.getData();
int raw_length = finalJPEG.getLength();
int raw_offset = finalJPEG.getOffset();
FileConnection filecon = null;
OutputStream out = null;
try {
filecon = (FileConnection) Connector.open(Dire,Connector.READ_WRITE);
if(!filecon.exists()){
filecon.mkdir();
}
filecon = (FileConnection) Connector.open(saveDire,Connector.READ_WRITE);
if(!filecon.exists()){
filecon.create();
}
out = filecon.openOutputStream();
out.write(raw_media_bytes, raw_offset, raw_length);
out.close();
filecon.close();
System.out.println("----------------file saved"+imageFilename);
} catch (IOException e) {
System.out.println("---------------===================- error saving the file");
};
try {
FileConnection fconn = (FileConnection)Connector.open(saveDire);
if (fconn.exists()) {
InputStream input = fconn.openInputStream();
int available = input.available();
final byte[] data1=IOUtilities.streamToBytes(input);
input.read(data1, 0, available);
eih1 = EncodedImage.createEncodedImage(data1,0,data1.length);
}
}catch (Exception ioe) {
System.out.println("error gettin bitmap details from the piture");
}
_bmap=eih1.getBitmap();
}
public Bitmap getbitmap()
{
return _bmap;
}
}
what should i do to prevent UI blocking, i want the perfect why to call that downloader class without stoping the process of parsing the other listfield content?

Answer 1

I think you may just have a simple syntax problem with the way you declared your thread object. See the BlackBerry documentation on Thread here
When you create a Thread, you normally either extend the Thread class with a subclass of your own, that implements the run() method, or you pass a new Runnable object in to the constructor of your Thread object. In your code, you actually declare a Thread instance, and create it, but do not give it a Runnable, or override the default run() method. So, this thread won't do anything in the background.
You have essentially declared a chunk of code within a local scope. That's what happens if you just put some code within a set of curly brackets ({ and }) that are not attached to anything:
Thread t = new Thread();
// this next curly bracket starts a "local scope". it is NOT part of Thread t!
{
String imageFilename = imageurlStrin.substring(imageurlStrin.lastIndexOf('/') + 1);
// The rest of your code here will not be executed on Thread t. It will be executed
// on the thread where you instantiate Thread t, right before you call t.start();
// If this code is called on the main/UI thread (which it probably is), then the
// network request will block the UI thread, which will stop the loading of the rest
// of the list.
};
t.start();
What you probably want is this:
Thread t = new Thread(new Runnable() {
public void run() {
String imageFilename = imageurlStrin.substring(imageurlStrin.lastIndexOf('/') + 1);
String saveDire = "file:///store/home/user/pictures/listfield/"+imageFilename;
try {
FileConnection fconn = (FileConnection)Connector.open(saveDire);
if (fconn.exists()) {
// do nothing
}
if (!fconn.exists()) {
UrlToImage bit = new UrlToImage(imageurlStrin);
pic = bit.getbitmap();
}
} catch (Exception ioe) {
System.out.println("error 18");
}
}
});
t.start();
Try that, and see if that fixes the problem.