As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance.
Closed 10 years ago.
I am developing a mobile app, for both Android and BlackBerry.
I've uploaded my latest application for OTA installation by including version code and version name into a plain text file on the server.
Within my app, how do I convert code version and version name from the plain-text format on my server to a string. I want to do this so I can have the app compare it's current version against what is available on the server, so that if a newer version on the server, the user will be offered an update to download.
Let's say you upload a file to your server, that contains a single line:
1.2.3.4
The process is similar for Android and BB:
1- Retrieve the file from the server. You'll probably have a byte array as result.
2- Convert it to a String with the proper encoding. In case the txt only contains numbers and dots, the encoding is not really important since these are ASCII chars, and ASCII chars are compatible with most usual default encodings like UTF-8 and ISO-8859. So we could probably instantiate the string without dealing with the encoding, like this: String fileContent = new String(byte[] downloadedData). Otherwise, make sure you know in advance the txt file encoding and instantiate the string with that encoding.
3- Split the string using the dots as separators. In Android you can do it like this: String[] splitted = String.split(fileContent, '.'), or use a StringTokenizer. In BB, as it is based in CLDC, this method in String is not available so you should code it yourself, or use/port one from a well tested library (like Apache Commons' org.apache.commons.lang3.StringUtils.split). After this step you'll have an array of strings, each string being a number ({"1","2","3","4"} in the example).
4- Now create a int array of the same length, and convert each string in the array to its equivalent int, using Integer.parseInt(splitted[i]) on each element i.
5- Get the version for your app and perform the same steps to get an array of int. In BB, you can call ApplicationDescriptor.currentApplicationDescriptor().getVersion(). In Android, PackageInfo.versionCode or PackageInfo.versionName, depending on what you have specified in the manifest.
6- Notice both arrays don't need to be of the same length. You could have written "1.2.3.4" in your txt, but have "1.2.3" in your AndroidManifest.xml or BlackBerry_App_Descriptor.xml. Normalize both resulting int arrays to have the same length (the lenght of the longer one), and fill the added elements with zeroes. Now you'll have two int arrays (in the example, txtVersion = {1,2,3,4} and appVersion = {1,2,3,0}). Iterate comparing versions one by one. The rule is: if txtVersion[i] > appVersion[i], then you are out of date and an upgrade is needed.
This answer is for the android part only.
To get the app version number and name from your application, you can do the following (as suggested by #ColorWP.com
Getting the app version and name:
String version_number = getPackageManager().getPackageInfo(getPackageName(), 0).versionName;
String version_name = getPackageManager().getPackageInfo(getPackageName(), 0).versionNumber;
To read your file from the net:
URL url = new URL("http://www.your.site/your.txt");
URLConnection connect = url.openConnection();
BufferedReader txtreader = new BufferedReader(new InputStreamReader(connect.getInputStream()));
String line = txtreader.readLine();
while (line != null) {
/* Code to Read your variables in this loop
(let us assume these would be:
server_app_version
server_app_name)
*/
}
Make sure you add Internet permission, as suggested by #ColorWP.com
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
Compare the version:
if (server_app_version.compareTo(version_number) != 0 || server_app_name.compareTo(version_name) != 0){
// Notify user to download the new version
}
Instead of using txt files it is better to output JSON from your server (Android provides some useful JSON decoding and encoding methods).
Setup the URL to the page that outputs the JSON as a static final variable in your Update activity, download it using any method you like. The following answer may be useful.
Afterwards, parse the JSON string by using the code in this answer.
When you get the newest version of the app from your server as string or int you can compare it to the local app's version which you can get using:
PackageInfo pInfo = getPackageManager().getPackageInfo(getPackageName(), 0);
String version = pInfo.versionCode;
// To get the version name use pInfo.versionName
Remember to add the INTERNET permission so your app can connect online:
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
Related
Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 9 years ago.
Improve this question
I have a large file of about 10 MB, I want to search a specific string, and this specific string may be used a lot of times in 10 Mb text file. I need results where this specific string is used. I want to do search like Google. For example when i write a string then google comes with matching Patterns . Your suggestions will be appreciated.
file formate
he is going to school.
we should do best deeds.
we should work hard.
.
.
.
.
Always speak truth.
i have search edit field in my application.
user write "should" in search edit field.and press search button.
a list should be opened in which searched words come with it's complete line.
for example result should be
we should do best deeds.
we should work hard.
A simple way to search a file and get a match "with context" is to use grep. For example, to match every line with "hello", and print one line before and three lines after, you would do
grep -b1 -a3 'hello' myBigFile.txt
You can use grep -E to allow for a wide range of PCRE regex syntax.
Without more detail it would be hard to give you a better answer.
EDIT 2
Now that you have explained your problem more clearly, here is a possible approach:
InputStream fileIn;
BufferedReader bufRd;
String line, pattern;
pattern = "should"; // get the pattern from the user, do not hard code. Example only
fileIn = new FileInputStream("myBigTextfile.txt");
bufRd = new BufferedReader(new InputStreamReader(fis, Charset.forName("UTF-8")));
while ((line = bufRd.readLine()) != null) {
if(line.contains(pattern)) {
System.out.println(line); // echo matching line to output
}
}
// Done with the file
br.close();
If you need to match with wildcards, then you might replace the line.contains with something that is a little more "hard core regex" - for example
matchPattern = Pattern.compile("/should.+not/");
(only need to do that once - after getting input, and before opening file) and change the condition to
if (matchPattern.matcher(line).find())
Note - code adapted from / inspired by https://stackoverflow.com/a/7413900/1967396 but not tested.
Note there are no for loops... maybe the boss will be happy now.
By the way - if you edit your original question with all the information you provided in the comments (both to this answer and to the original question) I think the question can be re-opened.
If you expect the user to do many searches it may be faster to read the entire file into memory once. But that's outside of the scope of your question, I think.
Thanks for reading this question. I am sure the experts on this site will be able to provide the help I need.
I am trying to write an app which allows users to edit the exif information of the photos on their Android Phone.
As a part of improved user experience, I want to apply data validation where ever possible.
For the Exif Tag - TAG_GPS_PROCESSING_METHOD I am not able to apply the validation correctly.
Here is the part of code that I have applied :
String strGPSProc = etGPSProc.getText().toString();
if(strGPSProc.equalsIgnoreCase("GPS") || strGPSProc.equalsIgnoreCase("CELLID") || strGPSProc.equalsIgnoreCase("WLAN") || strGPSProc.equalsIgnoreCase("MANUAL") ) {
returnValue = true;
}else {
returnValue=false;
showToast("Incorrect value for GPS Processing Method. Correct value options are GPS, CELLID, WLAN or MANUAL.");
etGPSProc.requestFocus();
}
This code checks if the value entered in the EditText meant for GPSProcessingMethod, has any one of the four prescribed value as described in the documentation of EXIF.
But when I try to save this using setAttribute() and saveAttributes() functions, a non catch-able exception appears in logcat.
Unsupported encoding for GPSProcessingMethod
I understand from Exif Documentation that values for GPSProcessingMethod needs to be stored with some header information.
I need some expert advise on how to implement this correctly, with out using any other 3rd part classes.
Accoridng to the Exif specification:
GPSProcessingMethod
A character string recording the name of the method used for location finding. The first byte indicates the character
code used (Table 6､Table 7), and this is followed by the name of the method. Since the Type is not ASCII, NULL
termination is not necessary
Atually, Table 6 lists the character codes as 8 byte sequences, so the above should probably read "The first bytes indicate...". Anyway, the character code designation for ASCII is defined as 41.H, 53.H, 43.H, 49.H, 49.H, 00.H, 00.H, 00.H., Unicode is (unsurprisingly) 55.H, 4E.H, 49.H, 43.H, 4F.H, 44.H, 45.H, 00.H. I guess these should be all you need.
Hope that helps.
EDIT:
Just discovered that ExifInterface.setAttribute() only supports String values... You could try encoding the value at the beginning of your string, but I doubt that would work. Sounds like the encoding should be handled by the setAttribute() or saveAttributes() method. Could it be a bug in the API? I had a look at the source code, but the actual writing of values is done by native code so I stopped digging further.
This question already has an answer here:
How to extract this string variable in android?
(1 answer)
Closed 9 years ago.
String test=["1","Low-level programming language",true]
Here i want to extract this string value and as i need to get only second value like "Low-level programming language".How to get this value using string functions in android?
Per your comment, I'm assuming that you have a single string that contains the entire text (including the brackets). In general, splitting comma-separated values is a fairly tricky process. For your specific string, though, it's kind of easy:
String test = "[\"1\",\"Low-level programming language\",true]";
String[] pieces = test.split(",");
String middle = pieces[1];
// now strip out the quotes:
middle = middle.substring(1, middle.length() - 1);
In general, you might want to look at using a general CSV parser like Apache Commons CSV or openCSV.
Alternatively, if this is JSON data (which looks more likely than CSV), take a look at using one of the Java JSON libraries listed here (scroll down the page to see the list).
First, I have researched this question a lot. I learned how to read from my text file in the assets folder. The problem is that I don't want to end up with a string because the file is actually an arraylist written using json and inside that arraylist are objects. I need to access one object only. Here's what I mean:
I have a Book class, which has an int called chapter, an int called title, and an int called pageNum. I created several Book objects and added them to an ArrayList. Then I used the following code to write my ArrayList to a text file (in a regular java project):
ArrayList<Book> aList = new ArrayList<Book>();
aList.add(book1);
//etc...add more Book objects here...
File aFile = new File("books.txt");
FileOutputStream aFileStream = new FileOutputStream(aFile);
JSONOutputStream jsonOut = new JSONOutputStream(aFileStream);
jsonOut.writeObject(aList);
jsonOut.close();
That code creates a text file which I then put into the /assets folder in my Android project because I want it included with the app. In a non-Android java project I could simply use the following code to repopulate an ArrayList so that I could parse Book obects from specific indexes:
File bFile = new File("books.txt");
FileInputStream bFileStream = new FileInputStream(bFile);
JSONInputStream jsonIn = new JSONInputStream(bFileStream);
Arraylist<Book> bList = (ArrayList<Book>) jsonIn.readObject();
Book aBook = bList.get(253); //some arbitrary index
The json code I'm using comes from quickconnectfamily.org. You have to add a file called qc_json.jar to the build path of your project. http://www.quickconnectfamily.org/qcjson/more.html
The problem in Android is when I read the file using InputStream, I can only get the entire file into a string, the code above doesn't work in Android. I can't wrap JSONInputStreams around an InputStream, only around a FileInputStream. But it seems I am unable to use
FileInputStream.
So what I need is a way to create an ArrayList rather than a string in my Android app.
Without giving away too much about my app, the app basically generates a random number and creates a Book object from that index in the ArrayList. Then the user is quizzed with info from that specific book. Sounds silly, but the real app is much cooler.
I'm open to solutions, alternative methods of storing objects in a text file, etc. Please don't simply post criticism about my grammar, syntax, or application idea. I'm pretty new to app development and I couldn't care less about personal opinions. If anyone wants to see
more code I can upload it, but it doesn't seem necessary at this point. Thanks.
I figured out the solution. I connected my Evo 4G and tested the app and it worked. Here's what I did:
I used the following method to read from the file, which is what I was doing before:
InputStream is = appContext.getAssets().open("books.txt");
int size = is.available();
buffer = new byte[size];
is.read(buffer);
is.close();
String bufferString = new String(buffer);
When you do this, you end up with a String of the entire file. This is what I was able to do before, but what I wanted was a way to convert the String to an ArrayList of Book objects. Here's how I accomplished this:
//convert string to JSONArray
jsonArray = new JSONArray(bufferString);
//parse an Object from a random index in the JSONArray
JSONObject anObject = jsonArray.getJSONObject(randomNum);
Book aBook = new Book();
aBook.setTitle((String) anObject.get("title"));
//you can continue to set the different attributes of the Book object using key/value pairs from the Book class (e.g. setPageNum, setChapter, etc).
I don't know, maybe that was obvious to some people, but I really couldn't find any examples that did this. In a different question someone mentioned using the json library native to Android org.json and so I tried that and it worked.
I want to know a good way to create a list in my android app. I have all info in my DB and want to load data from it each time I start the app and make a list from it (id and title).
What is the best approach?
Should I make a PHP-script that responds with a JSON encoded array with all list items or should I make an XML-file that generates each time the data in the DB changes that I import to the app each time it starts? or any other good way to do it?
Since all stuff are made by XML-files in android it feels like importing a XML would be a good thing, is it? And how do I import an XML-file from a web server into the app?
// Daniel
You can use either JSON or XML.
You can use the web service approach or you can include your db with your application.
In fact, I most often choose to create a sqlite3 database of my data and include it in the assets folder, which can be copied to the app's data folder on startup.
As for copying your sqlite3 database from assets/ to the db data directory, I found these instructions helpful.
In your situation I would pick JSON over XML for all the reason's stated in the following post: http://ajaxian.com/archives/json-vs-xml-the-debate
Plus, in android, there are JSON Array's built in by default so you don't have to do any extra passing of the code.
return new JSONArray("my json string goes here...");
Since we are talking about a mobile device, I would always generate changes in your php script rather than have a full sync as this will be a lot smaller in size that a full sync. However, you will need to give your user a option to do a full re-sync if this is applicable to your app. I would use a SQLite database to store the data and only update the changes in that.
To also make the stream smaller, you can gzip compress your output from php as this can be natively read by the android device. In my app, I compress 500kb down to ~110kb before transmitting, a huge saving on performance. Here a partial example of how to read the stream:
InputStream in = null;
HttpURLConnection httpConn = null; // you will have to write your on code for this bit.
if (httpConn.getContentEncoding() != null)
{
String contentEncoding = httpConn.getContentEncoding().toString();
if (contentEncoding.contains("gzip"))
{
in = new GZIPInputStream(httpConn.getInputStream());
}
}
else
{
in = httpConn.getInputStream();
}
I hope that this all makes sense, it's been a long day programming :)
Stu