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Converting a set of characters into a different string array using java

I am trying to read a data from a file. I have following code.
public void ReadFile()
{
File sdcard = android.os.Environment.getExternalStorageDirectory();
File directory = new File(sdcard.getAbsolutePath()+ "/MyDirectory");
File file = new File(directory,"textfile1.txt");
try (FileInputStream fis = new FileInputStream(file)) {
char stringComma = new Character(',');
System.out.println("Total file size to read (in bytes) : "+ fis.available());
int content;
while ((content = fis.read()) != -1) {
// convert to char and display it
Log.d(TAG, "reading a file");
System.out.print((char) content);
}
} catch (IOException e) {
e.printStackTrace();
}
}
I have file format as follows [textfile1.txt]
[12],84359768069 //some numbers
[34],56845745740
[44],36344679992
[99],46378467467
When i am reading this file each character will read at a time. I want to split this and store in different string arrays like
str1 = [12]
str2 = 84359768069
How i can achieve this?

You're currently reading a byte at a time, because you're using InputStream. That's the first thing to fix - you should be using a Reader for text data. The best approach is to wrap your InputStream in an InputStreamReader.
Next, it sounds like you want to read a line at a time rather than just a character at a time. The easiest way of doing that is to use a BufferedReader wrapping an InputStreamReader.
(If you were using Java 7+, all of this could be achieved very nicely using Files.newBufferedReader - you just need to supply the Path and the Charset. Until Android supports that, you'll need to just do the wrapping manually. It's not too painful though.)
One you're reading a line at a time, you then need to split the line by comma - look at using String.split for this. I would then suggest you create a class to store these two separate values. So each line will be transformed into an instance of your class.
Finally, create a List<YourCustomClass> and add to it as you read the file.
That's given an overview of how to achieve each step - hopefully enough detail to enable you to get going, but not spoon-feeding you enough to hamper you actually learning from the experience.

A simple solution would be to parse the readed characters:
public void ReadFile()
{
File sdcard = android.os.Environment.getExternalStorageDirectory();
File directory = new File(sdcard.getAbsolutePath()+ "/MyDirectory");
File file = new File(directory,"textfile1.txt");
try (FileInputStream fis = new FileInputStream(file)) {
char stringComma = new Character(',');
System.out.println("Total file size to read (in bytes) : "+ fis.available());
int content;
String str1="";
String str2 = "";
boolean commaFound=false;
while ((content = fis.read()) != -1) {
// convert to char and display it
Log.d(TAG, "reading a file");
if ((char)content==',')
{
commaFound = true;
}
else if ((char)content=="\n")
{
System.out.printlnt("str1="+str1+"\nstr2="+str2);
commaFound = false;
str1 = "";
str2 = "";
}
else
{
if (commaFound)
{
str2 += (char)content;
}
else
{
str1 += (char)content;
}
}
System.out.print((char) content);
}
} catch (IOException e) {
e.printStackTrace();
}
}

Lists and Files

How to write a list in a file using JAVA?
I am writing a program to search files in a directory and display it. I also have a condition that I should store the search result in a log file. So please help me doing this.
From comments:
public void saveSearchResult(List<String> SearchResult) throws FileNotFoundException {
File file1 = new File("D://result.log");
FileInputStream in = new FileInputStream("D://result.log");
FileOutputStream out = new FileOutputStream(file1);
DataInputStream din = new DataInputStream(in);
DataOutputStream dout = new DataOutputStream(out);
for (String search : getSearchResult()) {
//Not getting hw to do this
}
}

Place your results into a string. Then load it into the file as follows...
StringBuilder s = new StringBuilder();
for (String search : getSearchResult()) {
s.append(search); //add formatting here as desired
}
try (FileWriter t = new FileWriter(new File("result.log"))) {
t.write(s.toString());
} catch (Exception e) {
System.out.println(e.getMessage());
}
You should always use a try with resources statement as above because it will insure the resources are released. http://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html
For a growing string you should use StringBuilder.
You probably want to create multiple new log files in which case I would suggest replacing "result.log" with this following code
new SimpleDateFormat("YYYY-MM-dd_hh-mm-ss").format(new Date(
System.currentTimeMillis())) + ".log"
This will output your log files so it looks like this...
result_2014-02-13_5-19-44.log
year/month/day/hour/minute/second

Reading bytes from a file?

I need to read some data until file is opened at different times, but I'm not sure if pointer to data that have not been read yet is automatic increased?
My method:
//method for copy binary data from file to binaryDataBuffer
void readcpy(String fileName, int pos, int len) {
try {
File lxDirectory = new File(Environment.getExternalStorageDirectory().getPath() + "/DATA/EXAMPLE/");
File lxFile = new File(lxDirectory, (fileName);
FileInputStream mFileInputStream = new FileInputStream(lxFile);
mFileInputStream.read(binaryDataBuffer, pos, len);
}
catch (Exception e) {
Log.d("Exception", e.getMessage());
}
}
So, if I call this method first time and read and save 5 bytes for example, will be on next call of the method read out bytes from 5th byte? I don't close file after reading.

When you create an InputStream (because a FileInputStream is an InputStream), the stream is created anew each time, and starts at the beginning of the stream (therefore the file).
If you want to read from where you left off the last time, you need to retain the offset and seek -- or retain the initial input stream you have opened.
While you can seek into a stream (using .skip()), it is in any event NOT recommended to reopen each time, it is costly; also, when you are done with a stream, you should close it:
// with Java 7: in automatically closed
try (InputStream in = ...;) {
// do stuff
} catch (WhateverException e) {
// handle exception
}
// with Java 6
InputStream in = ...;
try {
// do stuff
} catch (WhateverException e) {
// handle exception
} finally {
in.close();
}

Try this code:
public String getStringFromFile (String filePath) throws Exception {
File fl = new File(filePath);
FileInputStream fin = new FileInputStream(fl);
BufferedReader reader = new BufferedReader(new InputStreamReader(fin));
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line).append("\n");
}
String ret = sb.toString();
//Make sure you close all streams.
fin.close();
reader.close();
return ret;
}

I find RandomAccessFile, it has offset which I need in my case.

Reading file and adding text to random character location

I have a text file with a sequence of 4194304 letters ranging from A-D all on one line (4 MB).
How would I randomly point to a character and replace the following set of characters to another file that is 100 characters long and write it out to a file?
I'm actually currently able to do this, but I feel it's really inefficient when I iterate it several times.
Here's an illustration of what I mentioned above:
Link to Imageshack
Here's how I'm currently achieving this:
Random rnum = new Random();
FileInputStream fin = null;
FileOutputStream fout = null;
int count = 10000;
FileInputStream fin1 = null;
File file1 = new File("fileWithSet100C.txt");
int randChar = 0;
while(cnt > 0){
try {
int c = 4194304 - 100;
randChar = rnum.nextInt(c);
File file = new File("file.txt");
//seems inefficient to initiate these guys over and over
fin = new FileInputStream(file);
fin1 = new FileInputStream(file1);
//would like to remove this and have it just replace the original
fout = new FileOutputStream("newfile.txt");
int byte_read;
int byte_read2;
byte[] buffer = new byte[randChar];
byte[] buffer2 = new byte[(int)file1.length()]; //4m
byte_read = fin.read(buffer);
byte_read2 = fin1.read(buffer2);
fout.write(buffer, 0, byte_read);
fout.write(buffer2, 0, byte_read2);
byte_read = fin.read(buffer2);
buffer = new byte[4096]; //4m
while((byte_read = (fin.read(buffer))) != -1){
fout.write(buffer, 0, byte_read);
}
cnt--;
}
catch (...) {
...
}
finally {
...
}
try{
File file = new File("newfile.txt");
fin = new FileInputStream(file);
fout = new FileOutputStream("file.txt");
int byte_read;
byte[] buffer = new byte[4096]; //4m
byte_read = fin.read(buffer);
while((byte_read = (fin.read(buffer))) != -1){
fout.write(buffer, 0, byte_read);
}
}
catch (...) {
...
}
finally {
...
}
Thanks for reading!
EDIT:
For those curious, here's the code I used to solve the aforementioned problem:
String stringToInsert = "insertSTringHERE";
byte[] answerByteArray = stringToInsert.getBytes();
ByteBuffer byteBuffer = ByteBuffer.wrap(answerByteArray);
Random rnum = new Random();
randChar = rnum.nextInt(4194002); //4MB worth of bytes
File fi = new File("file.txt");
RandomAccessFile raf = null;
try {
raf = new RandomAccessFile(fi, "rw");
} catch (FileNotFoundException e1) {
// TODO error handling and logging
}
FileChannel fo = null;
fo = raf.getChannel();
// Move to the beginning of the file and write out the contents
// of the byteBuffer.
try {
outputFileChannel.position(randChar);
while(byteBuffer.hasRemaining()) {
fo.write(byteBuffer);
}
} catch (IOException e) {
// TODO error handling and logging
}
try {
outputFileChannel.close();
} catch (IOException e) {
// TODO error handling and logging
}
try {
randomAccessFile.close();
} catch (IOException e) {
// TODO error handling and logging
}

You probably want to use Java's random-access file features. Sun/Oracle has a Random Access Files tutorial that will probably be useful to you.
If you can't use Java 7, then look at RandomAccessFile which also has seek functionality and has existed since Java 1.0.

First off, for your files you could have the Files as global variables. This would all you to use the file when ever you needed without reading it again. Also note that if you keep making new files then you will lose the data that you have already acquired.
For example:
public class Foo {
// Gloabal Vars //
File file;
public Foo(String location) {
// Do Something
file = new File(location);
}
public add() {
// Add
}
}
Answering your question, I would first read both files and then make all the changes you want in memory. After you have made all the changes, I would then write the changes to the file.
However, if the files are very large, then I would make all the changes one by one on the disk... it will be slower, but you will not run out of memory this way. For what you are doing I doubt you could use a buffer to help counter how slow it would be.
My overall suggestion would be to use arrays. For example I would do the following...
public char[] addCharsToString(String str, char[] newChars, int index) {
char[] string = str.toCharArray();
char[] tmp = new char[string.length + newChars.length];
System.arraycopy(string, 0, tmp, 0, index);
System.arraycopy(newChars, index, tmp, index, newChars.length);
System.arraycopy(string, index + newChars.length, tmp, index + newChars.length, tmp.length - (newChars.length + index));
return tmp;
}
Hope this helps!

How can I read a .txt file into a single Java string while maintaining line breaks?

Virtually every code example out there reads a TXT file line-by-line and stores it in a String array. I do not want line-by-line processing because I think it's an unnecessary waste of resources for my requirements: All I want to do is quickly and efficiently dump the .txt contents into a single String. The method below does the job, however with one drawback:
private static String readFileAsString(String filePath) throws java.io.IOException{
byte[] buffer = new byte[(int) new File(filePath).length()];
BufferedInputStream f = null;
try {
f = new BufferedInputStream(new FileInputStream(filePath));
f.read(buffer);
if (f != null) try { f.close(); } catch (IOException ignored) { }
} catch (IOException ignored) { System.out.println("File not found or invalid path.");}
return new String(buffer);
}
... the drawback is that the line breaks are converted into long spaces e.g. " ".
I want the line breaks to be converted from \n or \r to <br> (HTML tag) instead.
Thank you in advance.

What about using a Scanner and adding the linefeeds yourself:
sc = new java.util.Scanner ("sample.txt")
while (sc.hasNext ()) {
buf.append (sc.nextLine ());
buf.append ("<br />");
}
I don't see where you get your long spaces from.

You can read directly into the buffer and then create a String from the buffer:
File f = new File(filePath);
FileInputStream fin = new FileInputStream(f);
byte[] buffer = new byte[(int) f.length()];
new DataInputStream(fin).readFully(buffer);
fin.close();
String s = new String(buffer, "UTF-8");

You could add this code:
return new String(buffer).replaceAll("(\r\n|\r|\n|\n\r)", "<br>");
Is this what you are looking for?

The code will read the file contents as they appear in the file - including line breaks.
If you want to change the breaks into something else like displaying in html etc, you will either need to post process it or do it by reading the file line by line. Since you do not want the latter, you can replace your return by following which should do the conversion -
return (new String(buffer)).replaceAll("\r[\n]?", "<br>");

StringBuilder sb = new StringBuilder();
try {
InputStream is = getAssets().open("myfile.txt");
byte[] bytes = new byte[1024];
int numRead = 0;
try {
while((numRead = is.read(bytes)) != -1)
sb.append(new String(bytes, 0, numRead));
}
catch(IOException e) {
}
is.close();
}
catch(IOException e) {
}
your resulting String: String result = sb.toString();
then replace whatever you want in this result.

I agree with the general approach by #Sanket Patel, but using Commons I/O you would likely want File Utils.
So your code word look like:
String myString = FileUtils.readFileToString(new File(filePath));
There is also another version to specify an alternate character encoding.

You should try org.apache.commons.io.IOUtils.toString(InputStream is) to get file content as String. There you can pass InputStream object which you will get from
getAssets().open("xml2json.txt") *<<- belongs to Android, which returns InputStream*
in your Activity. To get String use this :
String xml = IOUtils.toString((getAssets().open("xml2json.txt")));
So,
String xml = IOUtils.toString(*pass_your_InputStream_object_here*);