How do I create a Java string from the contents of a file?


I've been using the idiom below for some time now. And it seems to be the most wide-spread, at least on the sites I've visited.

Is there a better/different way to read a file into a string in Java?

private String readFile(String file) throws IOException {
    BufferedReader reader = new BufferedReader(new FileReader (file));
    String         line = null;
    StringBuilder  stringBuilder = new StringBuilder();
    String         ls = System.getProperty("line.separator");

    try {
        while((line = reader.readLine()) != null) {

        return stringBuilder.toString();
    } finally {
9/12/2018 5:54:58 PM

If you're willing to use an external library, check out Apache Commons IO (200KB JAR). It contains an method that allows you to read an entire File into a String with one line of code.


import java.nio.charset.*;

public String readFile() throws IOException {
    File file = new File("data.txt");
    return FileUtils.readFileToString(file, StandardCharsets.UTF_8);

A very lean solution based on Scanner:

Scanner scanner = new Scanner( new File("poem.txt") );
String text = scanner.useDelimiter("\\A").next();
scanner.close(); // Put this call in a finally block

Or, if you want to set the charset:

Scanner scanner = new Scanner( new File("poem.txt"), "UTF-8" );
String text = scanner.useDelimiter("\\A").next();
scanner.close(); // Put this call in a finally block

Or, with a try-with-resources block, which will call scanner.close() for you:

try (Scanner scanner = new Scanner( new File("poem.txt"), "UTF-8" )) {
    String text = scanner.useDelimiter("\\A").next();

Remember that the Scanner constructor can throw an IOException. And don't forget to import and java.util.

Source: Pat Niemeyer's blog


import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;

String content = new String(Files.readAllBytes(Paths.get("readMe.txt")), StandardCharsets.UTF_8);

since java 7 you can do it this way.


If you're looking for an alternative that doesn't involve a third-party library (e.g. Commons I/O), you can use the Scanner class:

private String readFile(String pathname) throws IOException {

    File file = new File(pathname);
    StringBuilder fileContents = new StringBuilder((int)file.length());        

    try (Scanner scanner = new Scanner(file)) {
        while(scanner.hasNextLine()) {
            fileContents.append(scanner.nextLine() + System.lineSeparator());
        return fileContents.toString();

Guava has a method similar to the one from Commons IOUtils that Willi aus Rohr mentioned:


// ...

String text = Files.toString(new File(path), Charsets.UTF_8);

EDIT by PiggyPiglet
Files#toString is deprecated, and due for removal Octobor 2019. Instead use Files.asCharSource(new File(path), StandardCharsets.UTF_8).read();

EDIT by Oscar Reyes

This is the (simplified) underlying code on the cited library:

InputStream in = new FileInputStream(file);
byte[] b  = new byte[file.length()];
int len = b.length;
int total = 0;

while (total < len) {
  int result =, total, len - total);
  if (result == -1) {
  total += result;

return new String( b , Charsets.UTF_8 );

Edit (by Jonik): The above doesn't match the source code of recent Guava versions. For the current source, see the classes Files, CharStreams, ByteSource and CharSource in package.


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