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Combined Xml String Split Java

I am trying to split a combined text file. The combined text file has multiple xml files inside. I want to split on <?xml version='1.0'?> which is the start of every new xml inside the combined text file. Not sure what is the best way to do this. Currently this is what I have which does not split correctly.
Updated Code Working (fixed quotation in quotes problem added Pattern.quote):
Scanner scanner = new Scanner( new File("src/main/resources/Flume_Sample"), "UTF-8" );
String combinedText = scanner.useDelimiter("\\A").next();
scanner.close(); // Put this call in a finally block
String delimiter = "<?xml version=\"1.0\"?>";
String[] xmlFiles = combinedText.split("(?="+Pattern.quote(delimiter)+")");
for (int i = 0; i < xmlFiles.length; i++){
File file = new File("src/main/resources/output_"+i);
FileWriter writer = new FileWriter(file);
writer.write(xmlFiles[i]);
System.out.println(xmlFiles[i]);
writer.close();
}

The split method takes a regular expression string, so you may want to escape your delimiter String to a valid regex :
String[] xmlFiles = combinedText.split(Pattern.quote(delimiter));
See the Pattern.quote method .

Be also aware that you will load the entire initial file in memory if you proceed this way.
A streamed approach would perform better if the input file is large...

I would use something like this if you want to parse the data manually.
public static void parseFile(File file) throws AttributeException, LineException{
BufferedReader br = null;
String s = "";
int counter = 0;
if(file != null){
try{
br = new BufferedReader(new FileReader(file));
while((s = br.readLine()) != null){
if(s.contains("<?xml version='1.0'?>")){
//Write in new file with Stringbuffer and Filewritter.
}
}
br.close();
}catch (IOException e){
System.out.println(e);
}
}
}

Java/JSP: Preserve line breaks while writing to a local file from string variables

I need help to create read-write methods that write to a file and preserve the line breaks. The contents of the file are stored in a variable.
I use the following code to read a local HTML file:
public String scanLocalPage(String filePath) throws IOException
{
try{
BufferedReader reader = new BufferedReader(new FileReader(filePath));
StringBuilder sb = new StringBuilder();
String line;
while((line = reader.readLine())!= null){
sb=sb.append(line);
}
reader.close();
return sb.toString();
}
catch (Exception ee)
{
return "";
}
}
and the following method to write to a file:
public void writeToFile (String fileName, String fileContents) throws IOException
{
File outFile = new File (fileName);
try (FileWriter fw = new FileWriter(outFile)) {
fw.write(fileContents);
fw.close();
}
}
I use the above methods to read and write to a HTML file and a text file from String variables. The contents of the HTML file are generated in the code and the text file from a text area input field.
After writing to the file and then reading it again, the file contents are missing the line breaks. Any help to read/write with line breaks is appreciated.

You should use the system-dependent line separator string:
On UNIX systems, it returns "\n"; on Microsoft Windows systems it returns "\r\n".
String newLine = System.getProperty("line.separator");
sb = sb.append(line).append(newLine);
If you are using Java 7 or greater, you can use the System.lineSeparator() method.
String newLine = System.lineSeparator();
sb = sb.append(line).append(newLine);

When you use readline() the line breaks are removed. You have to re-insert them with
sb = sb.append(line).append("\n");

Cannot read first line of a file

I want to read the content of /etc/passwd file and get some data:
public void getLinuxUsers()
{
try
{
// !!! firstl line of the file is not read
BufferedReader in = new BufferedReader(new FileReader("/etc/passwd"));
String str;
str = in.readLine();
while ((str = in.readLine()) != null)
{
String[] ar = str.split(":");
String username = ar[0];
String userID = ar[2];
String groupID = ar[3];
String userComment = ar[4];
String homedir = ar[5];
System.out.println("Usrname " + username +
" user ID " + userID);
}
in.close();
}
catch (IOException e)
{
System.out.println("File Read Error");
}
}
I noticed two problems:
first line of the file is not read with root account information. I starts this way:
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
And how I can modify the code to use Java 8 NIO? I want to check first the existing of the file and then to proceed with reading the content.

The problem is that the first readLine() is outside the loop where the string is being processed, you should delete this:
str = in.readLine();
… Because in the next line (the one with the while) you're reassigning the str variable, that's why the first line is lost: the loop's body starts processing from the second line. Finally, to use Java nio, do something like this:
if (new File("/etc/passwd").exists()) {
Path path = Paths.get("/etc/passwd");
List<String> lines = Files.readAllLines(path, Charset.defaultCharset());
for (String line : lines) {
// loop body, same as yours
}
}

with nio:
Path filePath = Paths.get("/etc/passwd");
List<String> fileLines = Files.readAllLines(filePath);
Note that Files.readAllLines without 2nd parameter treats the file encoding as UTF-8, instead of system encoding (property "file.encoding")

BufferedReader: read multiple lines into a single string

I'm reading numbers from a txt file using BufferedReader for analysis. The way I'm going about this now is- reading a line using .readline, splitting this string into an array of strings using .split
public InputFile () {
fileIn = null;
//stuff here
fileIn = new FileReader((filename + ".txt"));
buffIn = new BufferedReader(fileIn);
return;
//stuff here
}
public String ReadBigStringIn() {
String line = null;
try { line = buffIn.readLine(); }
catch(IOException e){};
return line;
}
public ProcessMain() {
initComponents();
String[] stringArray;
String line;
try {
InputFile stringIn = new InputFile();
line = stringIn.ReadBigStringIn();
stringArray = line.split("[^0-9.+Ee-]+");
// analysis etc.
}
}
This works fine, but what if the txt file has multiple lines of text? Is there a way to output a single long string, or perhaps another way of doing it? Maybe use while(buffIn.readline != null) {}? Not sure how to implement this.
Ideas appreciated,
thanks.

You are right, a loop would be needed here.
The usual idiom (using only plain Java) is something like this:
public String ReadBigStringIn(BufferedReader buffIn) throws IOException {
StringBuilder everything = new StringBuilder();
String line;
while( (line = buffIn.readLine()) != null) {
everything.append(line);
}
return everything.toString();
}
This removes the line breaks - if you want to retain them, don't use the readLine() method, but simply read into a char[] instead (and append this to your StringBuilder).
Please note that this loop will run until the stream ends (and will block if it doesn't end), so if you need a different condition to finish the loop, implement it in there.

I would strongly advice using library here but since Java 8 you can do this also using streams.
try (InputStreamReader in = new InputStreamReader(System.in);
BufferedReader buffer = new BufferedReader(in)) {
final String fileAsText = buffer.lines().collect(Collectors.joining());
System.out.println(fileAsText);
} catch (Exception e) {
e.printStackTrace();
}
You can notice also that it is pretty effective as joining is using StringBuilder internally.

If you just want to read the entirety of a file into a string, I suggest you use Guava's Files class:
String text = Files.toString("filename.txt", Charsets.UTF_8);
Of course, that's assuming you want to maintain the linebreaks. If you want to remove the linebreaks, you could either load it that way and then use String.replace, or you could use Guava again:
List<String> lines = Files.readLines(new File("filename.txt"), Charsets.UTF_8);
String joined = Joiner.on("").join(lines);

Sounds like you want Apache IO FileUtils
String text = FileUtils.readStringFromFile(new File(filename + ".txt"));
String[] stringArray = text.split("[^0-9.+Ee-]+");

If you create a StringBuilder, then you can append every line to it, and return the String using toString() at the end.
You can replace your ReadBigStringIn() with
public String ReadBigStringIn() {
StringBuilder b = new StringBuilder();
try {
String line = buffIn.readLine();
while (line != null) {
b.append(line);
line = buffIn.readLine();
}
}
catch(IOException e){};
return b.toString();
}

You have a file containing doubles. Looks like you have more than one number per line, and may have multiple lines.
Simplest thing to do is read lines in a while loop.
You could return null from your ReadBigStringIn method when last line is reached and terminate your loop there.
But more normal would be to create and use the reader in one method. Perhaps you could change to a method which reads the file and returns an array or list of doubles.
BTW, could you simply split your strings by whitespace?
Reading a whole file into a single String may suit your particular case, but be aware that it could cause a memory explosion if your file was very large. Streaming approach is generally safer for such i/o.

This creates a long string, every line is seprateted from string " " (one space):
public String ReadBigStringIn() {
StringBuffer line = new StringBuffer();
try {
while(buffIn.ready()) {
line.append(" " + buffIn.readLine());
} catch(IOException e){
e.printStackTrace();
}
return line.toString();
}

Read XML, Replace Text and Write to same XML file via Java

Currently I am trying something very simple. I am looking through an XML document for a certain phrase upon which I try to replace it. The problem I am having is that when I read the lines I store each line into a StringBuffer. When I write the it to a document everything is written on a single line.
Here my code:
File xmlFile = new File("abc.xml")
BufferedReader br = new BufferedReader(new FileReade(xmlFile));
String line = null;
while((line = br.readLine())!= null)
{
if(line.indexOf("abc") != -1)
{
line = line.replaceAll("abc","xyz");
}
sb.append(line);
}
br.close();
BufferedWriter bw = new BufferedWriter(new FileWriter(xmlFile));
bw.write(sb.toString());
bw.close();
I am assuming I need a new line character when I prefer sb.append but unfortunately I don't know which character to use as "\n" does not work.
Thanks in advance!
P.S. I figured there must be a way to use Xalan to format the XML file after I write to it or something. Not sure how to do that though.

The readline reads everything between the newline characters so when you write back out, obviously the newline characters are missing. These characters depend on the OS: windows uses two characters to do a newline, unix uses one for example. To be OS agnostic, retrieve the system property "line.separator":
String newline = System.getProperty("line.separator");
and append it to your stringbuffer:
sb.append(line).append(newline);

Modified as suggested by Brel, your text-substituting approach should work, and it will work well enough for simple applications.
If things start to get a little hairier, and you end up wanting to select elements based on their position in the XML structure, and if you need to be sure to change element text but not tag text (think <abc>abc</abc>), then you'll want to call in in the cavalry and process the XML with an XML parser.
Essentially you read in a Document using a DocuemntBuilder, you hop around the document's nodes doing whatever you need to, and then ask the Document to write itself back to file. Or do you ask the parser? Anyway, most XML parsers have a handful of options that let you format the XML output: You can specify indentation (or not) and maybe newlines for every opening tag, that kinda thing, to make your XML look pretty.

Sb would be the StringBuffer object, which has not been instantiated in this example. This can added before the while loop:
StringBuffer sb = new StringBuffer();

Scanner scan = new Scanner(System.in);
String filePath = scan.next();
String oldString = "old_string";
String newString = "new_string";
String oldContent = "";
BufferedReader br = null;
FileWriter writer = null;
File xmlFile = new File(filePath);
try {
br = new BufferedReader(new FileReader(xmlFile));
String line = br.readLine();
while (line != null) {
oldContent = oldContent + line + System.lineSeparator();
line = br.readLine();
}
String newContent = oldContent.replaceAll(oldString, newString);
writer = new FileWriter(xmlFile);
writer.write(newContent);
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
scan.close();
br.close();
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
}