How to reduce memory when loading image from website? - memory

Question

I am using this Utility
public class Util_ImageLoader {
public static Bitmap _bmap;
Util_ImageLoader(String url) {
HttpConnection connection = null;
InputStream inputStream = null;
EncodedImage bitmap;
byte[] dataArray = null;
try {
connection = (HttpConnection) Connector.open(url + Util_GetInternet.getConnParam(), 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);
int multH;
int multW;
int currHeight = bitmap.getHeight();
int currWidth = bitmap.getWidth();
multH = Fixed32.div(Fixed32.toFP(currHeight), Fixed32.toFP(currHeight));// height
multW = Fixed32.div(Fixed32.toFP(currWidth), Fixed32.toFP(currWidth));// width
bitmap = bitmap.scaleImage32(multW, multH);
_bmap = bitmap.getBitmap();
}
public Bitmap getbitmap() {
return _bmap;
}
}
When I call it in a listfield which contains 10 childs, then the log keeps saying failed to allocate timer 0: no slots left.
This means the memory is being used up and no more memory to allocate again and as a result my main screen cannot start.

Answer 1

At the same time you have the following objects in memory:
// A buffer of about 10KB
byte[] responseData = new byte[10000];
// A string buffer which will grow up to the total response size
rawResponse.append(new String(responseData, 0, length));
// Another string the same length that string buffer
final String result = rawResponse.toString();
// Now another buffer the same size of the response.
dataArray = result.getBytes();
It total, if you downloaded n ascii chars, you have simultaneously 10KB, plus 2*n bytes in the first unicode string buffer, plus 2*n bytes in the result string, plus n bytes in dataArray. If I'm not wrong, that sums up to 5n + 10k. There's room for optimization.
Some improvements would be:
Check response code first, and then read the stream if response code is HTTP 200. No need to read if server returned an error.
Get rid of strings. No need to convert to string if after that you are converting again to bytes.
If images are large, don't store them in RAM while downloading. Instead, open a FileOutputStream and write to a temporary file as you read from input stream. Then, if temporary images are still large enough to be displayed, downscale them.