Develop Reference

Android Protected variable storage even after factory reset

I'm working on Aosp. I want to keep a variable in the system but When I use a shared preference, the variable is deleted when I perform a Factory reset. I need to change and save the variable I want to keep. Think like a Mac address

You can put all the variables you want to save into a json and save it in internal storage
and you can retrive it whenever you want
example code for read and write
private void saveConfig(String data) {
try {
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(openFileOutput("config.txt", Context.MODE_PRIVATE));
outputStreamWriter.write(data);
outputStreamWriter.close();
}
catch (IOException e) {
Log.e("Exception", "File write failed: " + e.toString());
} }
private String readConfig() {
String data = "";
try {
InputStream inputStream = context.openFileInput("config.txt");
if ( inputStream != null ) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
String receiveString = "";
StringBuilder stringBuilder = new StringBuilder();
while ( (receiveString = bufferedReader.readLine()) != null ) {
stringBuilder.append(receiveString);
}
inputStream.close();
data = stringBuilder.toString();
}
}
catch (FileNotFoundException e) {
Log.e("Error", "File not found: " + e.toString());
} catch (IOException e) {
Log.e("Error", "Can not read file: " + e.toString());
}
return data;
}
and your json can be
{
"variable1": "Value",
"variable2": false
}

Asynctask return null in SDK 23 and below device

I'm using Asynctask to pass the parameters of API. The Asynctask executing but the String Response in Asynctask PostExecute giving me a null for a device with SDK 23 and below. But when the device is equal or higher to SDK24(Nougat), it works perfectly and the data are being sent to the API however when the SDK is 23 and lower data are not being sent to API. Does anyone encounter this problem? Please enlighten me what I miss in my code or I do wrong code. Massive thank you.
private class sendToServerOfficial extends AsyncTask<String,Void,String> {
int statusCodeone;
String convert_txt_et_username = et_username.getText().toString();
String convert_txt_content = et_content.getText().toString();
#Override
protected String doInBackground(String... strings) {
try {
urlURL = new URL("http://www.testingsite.com/api/sendServer?/ip="+getIPAddress+"&phone_num="+getMobilePhoneNumber+"&user_text="+convert_txt_et_username+"&content_text="+convert_txt_content);
HttpURLConnection httpURLConnection = (HttpURLConnection) urlURL.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setRequestProperty("Content-Type","UTF-8");
httpURLConnection.connect();
statusCodeone = httpURLConnection.getResponseCode();
if (statusCodeone == 200) {
InputStream it = new BufferedInputStream(httpURLConnection.getInputStream());
InputStreamReader read = new InputStreamReader(it);
BufferedReader buff = new BufferedReader(read);
StringBuilder dta = new StringBuilder();
String chunks;
while ((chunks = buff.readLine()) != null) {
dta.append(chunks);
}
buff.close();
read.close();
return dta.toString();
}
}
catch (ProtocolException e) { e.printStackTrace(); }
catch (MalformedURLException e) { e.printStackTrace(); }
catch (IOException e) { e.printStackTrace(); }
return null;
}
#Override
protected void onPostExecute(String response) {
Toast.makeText(MainActivity.this, response + "Form is submitted already" + urlURL, Toast.LENGTH_LONG).show();
txt_inputURL.setEnabled(true);
btnClick.setClickable(true);
txt_inputURL.getText().clear();
}
}

A connection was leaked

I have a HTTP handler class that will handle the calls to a ASYNC method. Everything works fine, I am able to gather information from the json and display it inside of the application, however, I have noticed that I sometimes get the following in my log.
A connection to http://www.abc123.com/ was leaked. Did you forget to close a response body?
Is there any specific reason why I would be getting this. I am closing in within the try method in convertStreamToString.
public class HttpHandler {
private static final String TAG = HttpHandler.class.getSimpleName();
public HttpHandler() {
}
public String makeServiceCall(String reqUrl) {
String response = null;
try {
URL url = new URL(reqUrl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
// read the response
InputStream in = new BufferedInputStream(conn.getInputStream());
response = convertStreamToString(in);
} catch (MalformedURLException e) {
Log.e(TAG, "MalformedURLException: " + e.getMessage());
} catch (ProtocolException e) {
Log.e(TAG, "ProtocolException: " + e.getMessage());
} catch (IOException e) {
Log.e(TAG, "IOException: " + e.getMessage());
} catch (Exception e) {
Log.e(TAG, "Exception: " + e.getMessage());
}
return response;
}
private String convertStreamToString(InputStream is) {
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line;
try {
while ((line = reader.readLine()) != null) {
sb.append(line).append('\n');
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
}

Android HTTP connection and stream "gathering"

I "wrote" some code which should execute http request + stream download, however it does not seem to be working with the second part. It connects to the server, but without getting the expected data from it. The first few times it evena worked out, it displayed the html data from google, but afterwards,
I tried to optimize my code and threw something away, added something here and there, extended it by a class etc., which probably caused the "error". Here is my code:
public class MainActivity extends ActionBarActivity {
private static final String TAG = null;
TextView httpStuff;
public static String info;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
try {
AsyncDownload data = (AsyncDownload) new AsyncDownload().execute();
info = data.get();
httpStuff.setText(info);
} catch (Exception e){
e.printStackTrace();
}
}
public class AsyncDownload extends AsyncTask<Void, Void, String> {
protected String doInBackground(Void... params) {
Log.v(TAG, "Final Requsting URL is : :" + "google.com");
String line = "";
String responseData = null;
try {
StringBuilder sb = new StringBuilder();
String x = "";
URL httpurl = new URL("http://www.google.com");
URLConnection tc = httpurl.openConnection();
BufferedReader in = new BufferedReader(
new InputStreamReader(tc.getInputStream()));
while ((line = in.readLine()) != null) {
sb.append(line + "\n");
x = sb.toString();
}
responseData = new String(x);
}
catch (UnknownHostException uh){
Log.v("NewWebHelper", "Unknown host :");
uh.printStackTrace();
}
catch (FileNotFoundException e) {
Log.v("NewWebHelper", "FileNotFoundException :");
e.printStackTrace();
}
catch (IOException e) {
Log.v("NewWebHelper", "IOException :");
e.printStackTrace();
}
catch (Exception e) {
Log.v("NewWebHelper", "Exception :");
e.printStackTrace();
}
return responseData;
}
}
I just don't know what's the missing thing. I've been trying to solve this for hours with a big variety of data-passing versions of this, but nothing seems to be working. I'm counting on you, brainiacs.

Android: java.net.protocolException does not support output

I was previously using HttpClient and BasicNameValuePairs, for some reason i have to shift to HttpUrlConnection.
Hence this code, to make a HttpPost request with certain parameters:
public class MConnections {
static String BaseURL = "http://www.xxxxxxxxx.com";
static String charset = "UTF-8";
private static String result;
private static StringBuilder sb;
private static List<String> cookies = new ArrayList<String>();
public static String PostData(String url, String sa[][]) {
HttpURLConnection connection = null;
try {
connection = (HttpURLConnection) new URL(BaseURL + url)
.openConnection();
} catch (MalformedURLException e1) {
} catch (IOException e1) {
}
cookies = connection.getHeaderFields().get("Set-Cookie");
try{
connection.setDoOutput(true); // Triggers POST.
connection.setRequestProperty("Accept-Charset", charset);
connection.setRequestProperty("Content-Type",
"application/x-www-form-urlencoded;charset=" + charset);
}catch (Exception e) {
//Here i get Exception that "java.lang.IllegalStateException: Already connected"
}
OutputStream output = null;
String query = "";
int n = sa.length;
for (int i = 0; i < n; i++) {
try {
query = query + sa[i][0] + "="
+ URLEncoder.encode(sa[i][1], "UTF-8");
} catch (UnsupportedEncodingException e) {
}
}
try {
output = connection.getOutputStream();
output.write(query.getBytes(charset));
} catch (Exception e) {
//Here i get Exception that "android: java.net.protocolException: Does not support output"
} finally {
if (output != null)
try {
output.close();
} catch (IOException e) {
}
}
InputStream response = null;
try {
response = connection.getInputStream();
} catch (IOException e) {
//Here i get Exception that "java.io.IOException: BufferedInputStream is closed"
} finally {
//But i am closing it here
connection.disconnect();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
response, "iso-8859-1"), 8);
sb = new StringBuilder();
sb.append(reader.readLine());
String line = "0";
while ((line = reader.readLine()) != null) {
sb.append("\n" + line);
}
response.close();
result = sb.toString();
} catch (Exception e) {
}
return result;
}
}
But i get such Exceptions as commented in the code.
Actually i am calling MConnections.PostData() twice from my Activity using a AsyncTask. This might cause the Exception: Already Connected but i am using connection.disconnect. But why am i still getting that Exception?
Am i using it the wrong way?
Thank You

For the protocol exception, try adding the following before you call getOutputStream():
connection.setDoOutput(true);
Discovered this answer thanks to Brian Roach's answer here: https://stackoverflow.com/a/14026377/387781
Side note: I was having this issue on my HTC Thunderbolt running Gingerbread, but not on my Nexus 4 running Jelly Bean.