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Java - Write content from one file chunk by chunk (e.g. 8 Bytes) alternately into multiple files

So I've been trying to read the content of a text file and write the content chunk by chunk alternately into e.g. 2 new files.
I already tried multiple ways to do that but it won't work (OutputStream and FileOutputStream seems to be the most suitable).
Before i tried to part the file in e.g. 3 Parts and wrote the first part in one file, the second part in another and so on. Which worked perfectly fine with OutputStream and FileOutputStream.
But it won't work when i want to do it alternately.
To do it alternately i use the round robin algorithm, which on its own works fine.
I would be really thankful if you could show me some examples to do it!
public void splitFile(String filePath, int numberOfParts, long sizeOfParts[]) throws FileNotFoundException, IOException, SQLException {
long bytes = 8;
OutputStream partsPath[] = new OutputStream[numberOfParts];
long bytePositition[] = new long[numberOfParts];
long copy_size[] = new long[numberOfParts];
for (int i = 0; i < numberOfParts; i++) {
copy_size[i] = sizeOfParts[i];
partsPath[i] = new FileOutputStream(path); //Gets Path from my Database (works)
//System.out.println(cloudsTable.getCloudsPathsFromDatabase(i) + '\\' + name + (i + 1) + fileType);
}
InputStream file = new FileInputStream(filePath);
while (true) {
boolean done = true;
for (int i = 0; i < numberOfParts; i++) {
if (copy_size[i] > 0) {
done = false;
if (copy_size[i] > bytes) {
copy_size[i] -= bytes;
bytePositition[i] += bytes;
System.out.println("file " + i + " " + bytePositition[i]);
readWrite(file, bytePositition[i], partsPath[i]);
} else {
bytePositition[i] += copy_size[i];
System.out.println("rest file " + i + " " + bytePositition[i]);
readWrite(file, bytePositition[i], partsPath[i]);
copy_size[i] = 0;
}
}
}
if (done == true) {
break;
}
}
file.close();
for (int i = 0; i < partsPath.length; i++) {
partsPath[i].close();
}
}
private void readWrite(InputStream file, long bytes, OutputStream path) throws IOException {
byte[] buf = new byte[(int) bytes];
while (file.read(buf) != -1) {
path.write(buf);
path.flush();
}
}
What the code does is, it only write the content of the Originalfile in the first-copied file and the following files are empty
EDIT:
To clarify what the code should do is write the first 8 bytes to go to file 1, second 8 bytes to go to file 2, third 8 bytes to go to file 3, fourth 8 bytes to go to file 1, and so on, round robin, until file 1 is sizeOfParts[0] long, file 2 is sizeOfParts[1] long, and file 3 is sizeOfParts[2] long.

The main problem is that the readWrite() method is only supposed to copy one 8-byte block of bytes, but has a loop that makes it copy all the remaining bytes in the input file.
In addition, the code should be enhanced to use try-finally to close the files, and to correctly handle end-of-file, in case the input file is shorter than the sum of parts.
I would eliminate the readWrite() method, and consolidate the logic to prevent duplicate code, like this:
public void splitFile(String inPath, long[] sizeOfParts) throws IOException, SQLException {
final int numberOfParts = sizeOfParts.length;
String[] outPath = new String[numberOfParts];
// Gets Paths from Database here
InputStream in = null;
OutputStream[] out = new OutputStream[numberOfParts];
try {
in = new BufferedInputStream(new FileInputStream(inPath));
for (int part = 0; part < numberOfParts; part++)
out[part] = new BufferedOutputStream(new FileOutputStream(outPath[part]));
byte[] buf = new byte[8];
long[] remain = sizeOfParts.clone();
for (boolean done = false; ! done; ) {
done = true;
for (int part = 0; part < numberOfParts; part++) {
if (remain[part] > 0) {
int len = in.read(buf, 0, (int) Math.min(remain[part], buf.length));
if (len == -1) {
done = true;
break;
}
remain[part] -= len;
System.out.println("file " + part + " " + (sizeOfParts[part] - remain[part]));
out[part].write(buf, 0, len);
done = false;
}
}
}
} finally {
if (in != null)
in.close();
for (int part = 0; part < out.length; part++)
if (out[part] != null)
out[part].close();
}
}

String invalid length after writing to StringBuilder and ByteArrayOutputStream from FileInputStream, issue with "null characters"

The goal is to read a file name from a file, which is a max of 100 bytes, and the actual name is the file name filled with "null-bytes".
Here is what it looks like in GNU nano
Where .PKGINFO is the valid file name, and the ^# represent "null bytes".
I tried here with StringBuilder
package falken;
import java.io.*;
public class Testing {
public Testing() {
try {
FileInputStream tarIn = new FileInputStream("/home/gala/falken_test/test.tar");
final int byteOffset = 0;
final int readBytesLength = 100;
StringBuilder stringBuilder = new StringBuilder();
for ( int bytesRead = 1, n, total = 0 ; (n = tarIn.read()) != -1 && total < readBytesLength ; bytesRead++ ) {
if (bytesRead > byteOffset) {
stringBuilder.append((char) n);
total++;
}
}
String out = stringBuilder.toString();
System.out.println(">" + out + "<");
System.out.println(out.length());
} catch (Exception e) {
/*
This is a pokemon catch not used in final code
*/
e.printStackTrace();
}
}
}
But it gives an invalid String length of 100, while the output on IntelliJ shows the correct string passed withing the >< signs.
>.PKGINFO<
100
Process finished with exit code 0
But when i paste it here on StackOverflow I get the correct string with unknown "null-characters", whose size is actually 100.
>.PKGINFO <
What regex can i use to get rid of the characters after the valid file name?
The file I am reading is ASCII encoded.
I also tried ByteArrayOutputStream, with the same result
package falken;
import java.io.*;
import java.nio.charset.StandardCharsets;
public class Testing {
public Testing() {
try {
FileInputStream tarIn = new FileInputStream("/home/gala/falken_test/test.tar");
final int byteOffset = 0;
final int readBytesLength = 100;
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
for ( int bytesRead = 1, n, total = 0 ; (n = tarIn.read()) != -1 && total < readBytesLength ; bytesRead++ ) {
if (bytesRead > byteOffset) {
byteArrayOutputStream.write(n);
total++;
}
}
String out = byteArrayOutputStream.toString();
System.out.println(">" + out + "<");
System.out.println(out.length());
} catch (Exception e) {
/*
This is a pokemon catch not used in final code
*/
e.printStackTrace();
}
}
}
What could be the issue here?

Well, it seems to be reading null characters as actual characters, spaces in fact. If it's possible, see if you can read the filename, then, cut out the null characters. In your case, you need a data.trim(); and a data2 = data.substring(0,(data.length()-1))

You need to stop appending to the string buffer once you read the first null character from the file.
You seem to want to read a tar archive, have a look at the following code which should get you started.
byte[] buffer = new byte[500]; // POSIX tar header is 500 bytes
FileInputStream is = new FileInputStream("test.tar");
int read = is.read(buffer);
// check number of bytes read; don't bother if not at least the whole
// header has been read
if (read == buffer.length) {
// search for first null byte; this is the end of the name
int offset = 0;
while (offset < 100 && buffer[offset] != 0) {
offset++;
}
// create string from byte buffer using ASCII as the encoding (other
// encodings are not supported by tar)
String name = new String(buffer, 0, offset,
StandardCharsets.US_ASCII);
System.out.println("'" + name + "'");
}
is.close();
You really shouldn't use trim() on the filename, this will break whenever you encounter a filename with leading or trailing blanks.

Android Socket continue reading till a specific String sequence

I want to read from a socket till a specific String sequence like <END>. The problem is the server sometimes returns me the data in chunks that is when the text (JSON) is too long to be sent in packets. I want to make a logic where the socket keeps appending a String Builder until the stream ends at <END> and after that continue appending another message.
InputStreamReader inr = new InputStreamReader(socket.getInputStream());
BufferedReader br = new BufferedReader(inr);
byte[] resultBuff = new byte[0];
byte[] buff = new byte[99999];
int k;
StringBuilder sb = new StringBuilder();
while ((k = in .read(buff, 0, buff.length)) > -1) {
byte[] tbuff = new byte[resultBuff.length + k]; // temp buffer size = bytes already read + bytes last read
System.arraycopy(resultBuff, 0, tbuff, 0, resultBuff.length); // copy previous bytes
System.arraycopy(buff, 0, tbuff, resultBuff.length, k); // copy current lot
resultBuff = tbuff; // call the temp buffer as your result buff
System.out.println(resultBuff.length + " bytes read.");
String s = new String(resultBuff);
sb.append(s);
if (s.endsWith(DELIMITER)) {
String response = sb.toString().replace(DELIMITER, "").replace("\n", "").replace("\r", "");
System.out.println(response);
if (listener != null) {
listener.onMessageReceived(params[0], response);
} else {
Log.e(TAG, "Response :: listener.onMessageReceived null ");
}
resultBuff = new byte[0];
sb = new StringBuilder();
} else {
sb.append(s);
}
}
The goal here is to keep the while loop running so that the socket can keep reading whenever something comes in stream.

You can do something like this.
String str = "";
byte[] b = new byte[1024];
for(int r = 0; (r = is.read(b))!=-1;){
str += new String(b,0,r);
if(str.contains(DELIMITER)){
String message = str.substring(0,str.indexOf(DELIMITER));
str = str.substring(str.indexOf(DELIMITER)+DELIMITER.length());
//process message.
}
}
if(!str.isEmpty()){
//the JSON object was sent in a single chunk, porcess it
}
What this does is to store all the data read from the InputStream into the str String and when the str contains the DELIMITER it will extract the message from the str so it can be processed. This will fail if the buffer contains more then one message. You can use String[] messages = str.split(DELIMITER) to deal with that.
A better solution will be to use a Scanner, here is an example:
Scanner sc = new Scanner(in);
sc.useDelimiter(DELIMITER);
while(sc.hasNext()){
String message = sc.next();
// process message.
}

BufferedReader directly to byte[]

is there any possibility my following BufferedReader is able to put the input directly into a byte[]?
public static Runnable reader() throws IOException {
Log.e("Communication", "reader");
din = new DataInputStream(sock.getInputStream());
brdr = new BufferedReader(new InputStreamReader(din), 300);
boolean done = false;
while (!done) {
try {
char[] buffer = new char[200];
int length = brdr.read(buffer, 0, 200);
String message = new String(buffer, 0, length);
btrar = message.getBytes("ISO-8859-1");
int i=0;
for (int counter = 0; counter < message.length(); counter++) {
i++;
System.out.println(btrar[counter] + " = " + " btrar " + i);
}
...
thats the part of the reader, pls have a look.
I want the input directly to btrar,

is there any possibility my following BufferedReader is able to put the input directly into a byte[]?
Any Reader is designed to let you read characters, not bytes. To read binary data, just use an InputStream - using BufferedInputStream to buffer it if you want.
It's not really clear what you're trying to do, but you can use something like:
BufferedInputStream input = new BufferedInputStream(sock.getInputStream());
while (!done) {
// TODO: Rename btrar to something more meaningful
int bytesRead = input.read(btrar);
// Do something with the data...
}

Java: Read up to x chars from a file into array

I want to read a text file and store its contents in an array where each element of the array holds up to 500 characters from the file (i.e. keep reading 500 characters at a time until there are no more characters to read).
I'm having trouble doing this because I'm having trouble understanding the difference between all of the different ways to do IO in Java and I can't find any that performs the task I want.
And will I need to use an array list since I don't initially know how many items are in the array?

It would be hard to avoid using ArrayList or something similar. If you know the file is ASCII, you could do
int partSize = 500;
File f = new File("file.txt");
String[] parts = new String[(f.length() + partSize - 1) / partSize];
But if the file uses a variable-width encoding like UTF-8, this won't work. This code will do the job.
static String[] readFileInParts(String fname) throws IOException {
int partSize = 500;
FileReader fr = new FileReader(fname);
List<String> parts = new ArrayList<String>();
char[] buf = new char[partSize];
int pos = 0;
for (;;) {
int nRead = fr.read(buf, pos, partSize - pos);
if (nRead == -1) {
if (pos > 0)
parts.add(new String(buf, 0, pos));
break;
}
pos += nRead;
if (pos == partSize) {
parts.add(new String(buf));
pos = 0;
}
}
return parts.toArray(new String[parts.size()]);
}
Note that FileReader uses the platform default encoding. To specify a specific encoding, replace it with new InputStreamReader(new FileInputStream(fname), charSet). It bit ugly, but that's the best way to do it.

An ArrayList will definitely be more suitable as you don't know how many elements you're going to have.
There are many ways to read a file, but as you want to keep the count of characters to get 500 of them, you could use the read() method of the Reader object that will read character by character. Once you collected the 500 characters you need (in a String I guess), just add it to your ArrayList (all of that in a loop of course).
The Reader object needs to be initialized with an object that extends Reader, like an InputStreamReader (this one take an implementation of an InputStream as parameter, a FileInputStream when working with a file as input).

Not sure if this will work, but you might want to try something like this (Caution: untested code):
private void doStuff() {
ArrayList<String> stringList = new ArrayList<String>();
BufferedReader in = null;
try {
in = new BufferedReader(new FileReader("file.txt"));
String str;
int count = 0;
while ((str = in.readLine()) != null) {
String temp = "";
for (int i = 0; i <= str.length(); i++) {
temp += str.charAt(i);
count++;
if(count>500) {
stringList.add(temp);
temp = "";
count = 0;
}
}
if(count>500) {
stringList.add(temp);
temp = "";
count = 0;
}
}
} catch (IOException e) {
// handle
} finally {
try {
in.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}