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Write multiple files with same string without hanging the UI

I am working on an Android App that changes the CPU Frequency when a foreground app changes. The frequencies for the foreground app is defined in my application itself. But while changing the frequencies my app has to open multiple system files and replace the frequency with my text. This makes my UI slow and when I change apps continuously, it makes the systemUI crash. What can I do to write these multiple files all together at the same time?
I have tried using ASynctaskLoader but that too crashes the SystemUI later.
public static boolean setFreq(String max_freq, String min_freq) {
ByteArrayInputStream inputStream = new ByteArrayInputStream(max_freq.getBytes(Charset.forName("UTF-8")));
ByteArrayInputStream inputStream1 = new ByteArrayInputStream(min_freq.getBytes(Charset.forName("UTF-8")));
SuFileOutputStream outputStream;
SuFileOutputStream outputStream1;
try {
if (max_freq != null) {
int cpus = 0;
while (true) {
SuFile f = new SuFile(CPUActivity.MAX_FREQ_PATH.replace("cpu0", "cpu" + cpus));
SuFile f1 = new SuFile(CPUActivity.MIN_FREQ_PATH.replace("cpu0", "cpu" + cpus));
outputStream = new SuFileOutputStream(f);
outputStream1 = new SuFileOutputStream(f1);
ShellUtils.pump(inputStream, outputStream);
ShellUtils.pump(inputStream1, outputStream1);
if (!f.exists()) {
break;
}
cpus++;
}
}
} catch (Exception ex) {
}
return true;
}

I assume SuFile and SuFileOutputStream are your custom implementations extending Java File and FileOutputStream classes.
Couple of points need to be fixed first.
f.exists() check should be before initializing OutputStream, otherwise it will create the file before checking exists or not. This makes your while loop to become an infinite loop.
as #Daryll suggested, use the number of CPUs with while/for loop. I suggest using for loop.
close your streams after pump(..) method call.
If you want to keep the main thread free, then you can do something like this,
see this code segment:
public static void setFreq(final String max_freq, final String min_freq) {
new Thread(new Runnable() {
//Put all the stuff here
}).start();
}
This should solve your problem.

Determine the number of CPUs before hand and use that number in your loop rather than using a while (true) having to do SuFile.exists() every cycle.
I don't know what SuFileOutputStream is but you may need to close those file output streams or find a faster way to write the file if that implementation is too slow.

Read the five score in a textfile then print them back with the new score added to the list - ANDROID

In my program when the player submits a score it gets added to a local text file called localHighScores. This is list of the top five score the player has achieved while on that specific device.
I wasn't sure how to write to a new line using FileOutputStream (if you know please share), so instead I've inputted a space in between each score. Therefore what I am trying to do is when the player clicks submit the program will open the file and read any current data is saved. It will save it to an String Array, each element being one of the five score in the text file and when it hits a 'space' in the fie it will add the score just read to the write array element
The code I currently have is as follows:
String space = " ";
String currentScoreSaved;
String[] score = new String[5];
int i = 0;
try
{
BufferedReader inputReader = new BufferedReader(new InputStreamReader(openFileInput("localHighScore.txt")));
String inputString;StringBuffer stringBuffer = new StringBuffer();
while ((inputString = inputReader.readLine()) != null && i < 6)
{
if((inputString = inputReader.readLine()) != space)
{
stringBuffer.append(inputString + "\n");
i++;
score[i] = stringBuffer.toString();
}
}
currentScoreSaved = stringBuffer.toString();
FileOutputStream fos = openFileOutput("localHighScore.txt", Context.MODE_PRIVATE);
while (i < 6)
{
i++;
fos.write(score[i].getBytes());
fos.write(space.getBytes());
}
fos.write(localHighScore.getBytes());
//fos.newLine(); //I thought this was how you did a new line but sadly I was mistaken
fos.close();
}
catch(Exception e)
{
e.printStackTrace();
}
Now you will notice this doesn't re arrange the score if a new highscore is achieved. That I am planning on doing next. For the moment I am just trying to get the program to do the main thing which is read in the current data, stick it in an Array then print it back to that file along with the new score
Any Ideas how this might work, as currently it's printing out nothing even when I had score in the textfile before hand

I'm only a first year student in Java programming and I am a new user here at stackoverflow.com, so pardon me if coding for android has some special rules I don't know about, which prevents this simple and humble example from working. But here is how I would read from a file in the simplest of ways.
File tempFile = new File("<SubdirectoryIfAny/name_of_file.txt");
Scanner readFile = new Scanner( tempFile );
// Assuming that you can structure the file as you please with fx each bit of info
// on a new line.
int counter = 0;
while ( readFile.hasNextLine() ) {
score[counter] = readFile.nextLine();
counter++;
}
As for the writing back to the file? Put it in an entirely different method and simply make a simplified toString-like method, that prints out all the values the exact way you want them in the file, then create a "loadToFile" like method and use the to string method to print back into the file with a printstream, something like below.
File tempFile = new File("<SubdirectoryIfAny/name_of_file.txt");
PrintStream write = new PrintStream(tempFile);
// specify code for your particular program so that the toString method gets the
// info from the string array or something like that.
write.print( <objectName/this>.toStringLikeMethod() );
// remember the /n /n in the toStringLikeMethod so it prints properly in the file.
Again if this is something you already know, which is just not possible in this context please ignore me, but if not I hope it was useful. As for the exceptions, you can figure that you yourself. ;)

Since you are a beginner, and I assume you are trying to get things off the ground as quickly as possible, I'd recommend using SharedPreferences. Basically it is just a huge persistent map for you to use! Having said that... you should really learn about all the ways of storage in Android, so check out this document:
http://developer.android.com/guide/topics/data/data-storage.html
The Android docs are awesome! FYI SharedPreferences may not be the best and awesomest way to do this... but I'm all for quick prototyping as a learner. If you want, write a wrapper class around SharedPreferences.

java.lang.nosuchfielderror in j2me app

Hey Hi Friends I am created one j2me app. it runs perfectly in Emulator but in Mobile it showing error like java.lang.nosuchfielderror:No such field HEADERS.[[Ljava/lang/String;.
Why this happening with mobile, it runs good in emulator......
Please help me to remove this error......
public String connectPhoneName() throws Exception{
String url = "http://122.170.122.186/Magic/getPhonetype.jsp";
String phoneType;
if ((conn = connectHttp.connect(url, HEADERS)) != null) {
if ((in = connectHttp.getDataInputStream(conn)) != null) {
byte[] data = connectHttp.readDATA(in, 100);
phoneType = new String(data);
System.out.println("DATA : " + phoneType);
} else {
throw new Exception("ERROR WHILE OPENING INPUTSTREAM");
}
} else {
throw new Exception("COULD NOT ESTABLISH CONNECTION TO THE SERVER");
}
return phoneType;
}
In this code i have used HEADERS.

It looks like your app is using some (I guess) or static final or final field of some library class that does not exist in the profile of Java ME your mobile device implements.
But I can't figure out where that field comes from. Perhaps you should search your codebase for use of "HEADER" as an identifier ...
If the HEADER field is properly declared in your codebase (your MagiDEF interface) and the code you showed is using the HEADER from that interface, then you must have something wrong with your build or deployment process. Specifically, you are not deploying the version of MagiDEF that your code (above) has been compiled against. Maybe you've got an old version of something in some JAR file?
Basically, the error indicates that you have a binary incompatibility between some of the classes / interfaces that make up your app.

How to read and update row in file with Java

currently i creating a java apps and no database required
that why i using text file to make it
the structure of file is like this
unique6id username identitynumber point
unique6id username identitynumber point
may i know how could i read and find match unique6id then update the correspond row of point ?
Sorry for lack of information
and here is the part i type is
public class Cust{
string name;
long idenid, uniqueid;
int pts;
customer(){}
customer(string n,long ide, long uni, int pt){
name = n;
idenid = ide;
uniqueid = uni;
pts = pt;
}
FileWriter fstream = new FileWriter("Data.txt", true);
BufferedWriter fbw = new BufferedWriter(fstream);
Cust newCust = new Cust();
newCust.name = memUNTF.getText();
newCust.ic = Long.parseLong(memICTF.getText());
newCust.uniqueID = Long.parseLong(memIDTF.getText());
newCust.pts= points;
fbw.write(newCust.name + " " + newCust.ic + " " + newCust.uniqueID + " " + newCust.point);
fbw.newLine();
fbw.close();
this is the way i text in the data
then the result inside Data.txt is
spencerlim 900419129876 448505 0
Eugene 900419081234 586026 0
when user type in 586026 then it will grab row of eugene
bind into Cust
and update the pts (0 in this case, try to update it into other number eg. 30)
Thx for reply =D

Reading is pretty easy, but updating a text file in-place (ie without rewriting the whole file) is very awkward.
So, you have two options:
Read the whole file, make your changes, and then write the whole file to disk, overwriting the old version; this is quite easy, and will be fast enough for small files, but is not a good idea for very large files.
Use a format that is not a simple text file. A database would be one option (and bear in mind that there is one, Derby, built into the JDK); there are other ways of keeping simple key-value stores on disk (like a HashMap, but in a file), but there's nothing built into the JDK.

You can use OpenCSV with custom separators.
Here's a sample method that updates the info for a specified user:
public static void updateUserInfo(
String userId, // user id
String[] values // new values
) throws IOException{
String fileName = "yourfile.txt.csv";
CSVReader reader = new CSVReader(new FileReader(fileName), ' ');
List<String[]> lines = reader.readAll();
Iterator<String[]> iterator = lines.iterator();
while(iterator.hasNext()){
String[] items = (String[]) iterator.next();
if(items[0].equals(userId)){
for(int i = 0; i < values.length; i++){
String value = values[i];
if(value!=null){
// for every array value that's not null,
// update the corresponding field
items[i+1]=value;
}
}
break;
}
}
new CSVWriter(new FileWriter(fileName), ' ').writeAll(lines);
}

Use InputStream(s) and Reader(s) to read file.
Here is a code snippet that shows how to read file.
BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream("c:/myfile.txt")));
String line = null;
while ((line = reader.readLine()) != null) {
// do something with the line.
}
Use OutputStream and Writer(s) to write to file. Although you can use random access files, i.e. write to the specific place of the file I do not recommend you to do this. Much easier and robust way is to create new file every time you have to write something. I know that it is probably not the most efficient way, but you do not want to use DB for some reasons... If you have to save and update partial information relatively often and perform search into the file I'd recommend you to use DB. There are very light weight implementations including pure java implementations (e.g. h2: http://www.h2database.com/html/main.html).

FMJ Webcam capture example

I've been searching for while now and I can't find a simple example of how to capture a webcam stream with FMJ. Are there any tutorials or examples available which could help me?

I have been working with FMJ for a while and I haven't found many examples to start with either. What I would do is to explore the FmjStudio class that has the webcam functionality integrated and its pretty straight forward.
For bob:
What you want is FMJ. FMJ uses an DataSource implementation for civil to use it with JMF. I would recommend you to go to http://fmj-sf.net/ download the latest source and explore FmjStudio aswell since it uses civil to capture.
For theDude:
You are right, you can use JMF aswell but the same code you use for JMF will most likely work with FMJ (maybe with a coupla changes) and the performance will be much better, specially if you want a wide range of different webcams to work with your software.

I know this isn't what you want to hear, but I've used JMF for this task and it works very well. There are enough examples online to get a simple web cam capture app running pretty easily. I'll post more if you're interested.

The following code would get you started.
GlobalCaptureDevicePlugger.addCaptureDevices();
Vector<CaptureDeviceInfo> audioCapDevList = CaptureDeviceManager.getDeviceList(null);
if (audioCapDevList.size() != 0) {
for (int i = 0; i < audioCapDevList.size(); i++) {
audioCapDevInfo = audioCapDevList.elementAt(i);
Format[] videoFormats = audioCapDevInfo.getFormats();
System.out.println(audioCapDevInfo);
if (audioCapDevInfo.getName().startsWith("vfw:")) { // assume the name of the webcam starts with vfw:
for (int j = 0; j < videoFormats.length; j++) {
if (videoFormats[j] instanceof VideoFormat) {
currentFormat = (VideoFormat) videoFormats[i];
break;
}
}
System.out.println(currentFormat);
if (currentFormat == null) {
System.err.println("Search for VideoFormat failed");
System.exit(-1);
}
audioCapDevLoc = audioCapDevInfo.getLocator();
}
}
}
Please make sure the native libraries (civil.dll and jdshow.dll) are loaded into the JVM. Otherwise, you would get an java.lang.UnsatisfiedLinkError. The following code may do the job for you.
System.setProperty("java.library.path", "D:/fmj-sf/native/win32-x86/");
Field fieldSysPath;
try {
fieldSysPath = ClassLoader.class.getDeclaredField("sys_paths");
fieldSysPath.setAccessible(true);
fieldSysPath.set(null, null);
} catch (Exception e) {
e.printStackTrace();
}