Save content of File as String in Java?

Question

I was working a little bit with config files and file reader classes in java. I always read/wrote in the files with arrays because I was working with objects. This looked a little bit like this:

public void loadUserData(ArrayList<User> arraylist) {
 try {
 List<String> lines = Files.readAllLines(path, Charset.defaultCharset());
 for(String line : lines) {
 String[] userParams = line.split(";");
 String name = userParams[0];
 String number= userParams[1];
 String mail = userParams[2];
 arraylist.add(new User(name, number, mail));
 } 
 } catch (IOException e) {
 e.printStackTrace();
 }
}

This works fine, but how can I save the content of a file as only one single string?

When I read a file, the string I use should be the exact same as the content of the file (without the use of arrays or line splits). how can I do that?

Edit:

I try to read a SQL-Statement out of a file to use it with JDBC later on. That's why I need the content of the File as a single String

• muffin: Oh, I'm sorry that I didn't tell above. I try to read a SQL-Statement out of a file to use it with JDBC later on. That's why I need the content of the File as a single String
• Paul: I muffin he means, "How do I save the entire contents of a text file into a single String?".
• rags: stackoverflow.com/questions/326390/…
• marsze: see stackoverflow.com/questions/3402735/… or stackoverflow.com/questions/326390/…

Answer 1

This method will work

public static void readFromFile() throws Exception{
 FileReader fIn = new FileReader("D:\\Test.txt");
 BufferedReader br = new BufferedReader(fIn);
 String line = null;
 StringBuilder sb = new StringBuilder();
 while ((line = br.readLine()) != null) {
 sb.append(line);
 sb.append("\n");
 }
 String text = sb.toString();
 System.out.println(text);
}

Answer 2

I hope this is what you need:

public void loadUserData(ArrayList<User> arraylist) {
 StringBuilder sb = new StringBuilder();
 try {
 List<String> lines = Files.readAllLines(path, Charset.defaultCharset());
 for(String line : lines) {
 // String[] userParams = line.split(";");
 //String name = userParams[0];
 //String number= userParams[1];
 //String mail = userParams[2];
 sb.append(line);
 } 
 String jdbcString = sb.toString();
 System.out.println("JDBC statements read from file: " + jdbcString );
 } catch (IOException e) {
 e.printStackTrace();
 }
}

or maybe this:

String content = new Scanner(new File("filename")).useDelimiter("\\Z").next();
System.out.println(content);

• Paul: Don't you need to add a space (or something) between the lines? The javadoc for readAllLines doesn't specify whether it retains or discards the line ends. If it discards them - which is consistent with the way LineNumberReader, and other Java methods, treat them - you will want to add a space after each appended line, I think.
• Juned Ahsan: @Paul As he mentioned the file contains sql scripts so i assumed them to be delimited by ';'. Also the idea is to help to move things but not to do the entire things for the questioner. I think he is able to move :-)

Answer 3

Just do that:

final FileChannel fc;
final String theFullStuff;
try (
 fc = FileChannel.open(path, StandardOpenOptions.READ);
) {
 final ByteBuffer buf = ByteBuffer.allocate(fc.size());
 fc.read(buf);
 theFullStuff = new String(buf.array(), theCharset);
}

nio for the win! :p

Answer 4

You could always create a Buffered reader e.g.

File anInputFile = new File(/*input path*/);
FileReader aFileReader = new FileReader(anInputFile);
BufferedReader reader = new BufferedReader(aFileReader)
String yourSingleString = "";
String aLine = reader.readLine();
while(aLine != null)
{
 singleString += aLine + " ";
 aLine = reader.readLine();
}

• muffin: Not bad, but the answer of Juned Ahsan is even better... Thanks for your help anyway :)
• Ravi K Thapliyal: Prefer to use a StringBuilder. Then use its toString() method.