I am making a multiplayer drawing application for android and I need to send the drawings that every user made to one player. I am using a server socket for this.
First thing I do is convert the Bitmap to a byte array, so I can send it to the Host with host.write(byteArray);
Bitmap bitmapImage = drawView.getBitmap();
byte[] byteArray = getByteArray(bitmapImage);
byteArrayLength = byteArray.length;
MainWifiActivity.SendReceive host = MainWifiActivity.sendReceiveHost;
if (host != null) {
host.write(byteArray);
}
The following code is my SendReceive class, which listenes to the inputStream and then starts a Handler, that is supposed to save the Bitmap to Internal Storage
public class SendReceive extends Thread {
private Socket socket;
private InputStream inputStream;
private OutputStream outputStream;
public SendReceive(Socket s) {
socket = s;
try {
inputStream = s.getInputStream();
outputStream = s.getOutputStream();
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void run() {
byte[] buffer = new byte[1024];
int bytes;
int filesize;
while (socket != null) {
try {
filesize = DrawingActivity.byteArrayLength;
if(buffer.length != filesize && filesize > 0){
buffer = new byte[filesize];
}
bytes = inputStream.read(buffer,0 ,buffer.length);
if (bytes > 0) {
Message mesg = handler.obtainMessage(IMAGE_MSG, bytes, -1, buffer);
mesg.sendToTarget();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
And the Handler:
Handler handler = new Handler(new Handler.Callback() {
@Override
public boolean handleMessage(Message msg) {
switch (msg.what) {
case IMAGE_MSG:
byte[] byteArray = (byte[]) msg.obj;
Bitmap bitmap = BitmapFactory.decodeByteArray(byteArray, 0, byteArray.length);
saveBitmapToInternalStorage(bitmap);
}
return false;
}
});
In the saveBitmapToInternalStorage Method I get a java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.graphics.Bitmap.compress(android.graphics.Bitmap$CompressFormat, int, java.io.OutputStream)' on a null object reference
private void saveBitmapToInternalStorage(Bitmap bmp) {
File directory = getApplicationContext().getDir("imageDir", Context.MODE_PRIVATE);
File myPath = new File(directory, UUID.randomUUID().toString() + ".png");
FileOutputStream fos = null;
try {
fos = new FileOutputStream(myPath);
bmp.compress(Bitmap.CompressFormat.PNG, 100, fos);
} catch (Exception e) {
Log.d("HELLO", "MY ERROR: " + e);
} finally {
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
I know that BitmapFactory.decodeByteArray returns the decoded bitmap, or null if the image could not be decoded.
But why could it not be decoded?
