Java – How to read / convert an InputStream into a String in Java?

Java – How to read / convert an InputStream into a String in Java?

Ways to convert an InputStream to a String:

  1. Using IOUtils.toString (Apache Utils)

    String result = IOUtils.toString(inputStream, StandardCharsets.UTF_8);
  2. Using CharStreams (Guava)

    String result = CharStreams.toString(new InputStreamReader(
          inputStream, Charsets.UTF_8));
  3. Using Scanner (JDK)

    Scanner s = new Scanner(inputStream).useDelimiter("\\A");
    String result = s.hasNext() ? s.next() : "";
  4. Using Stream API (Java 8). Warning: This solution converts different line breaks (like \r\n) to \n.

    String result = new BufferedReader(new InputStreamReader(inputStream))
      .lines().collect(Collectors.joining("\n"));
  5. Using parallel Stream API (Java 8). Warning: This solution converts different line breaks (like \r\n) to \n.

    String result = new BufferedReader(new InputStreamReader(inputStream)).lines()
       .parallel().collect(Collectors.joining("\n"));
  6. Using InputStreamReader and StringBuilder (JDK)

    final int bufferSize = 1024;
    final char[] buffer = new char[bufferSize];
    final StringBuilder out = new StringBuilder();
    Reader in = new InputStreamReader(stream, StandardCharsets.UTF_8);
    int charsRead;
    while((charsRead = in.read(buffer, 0, buffer.length)) > 0) {
        out.append(buffer, 0, charsRead);
    }
    return out.toString();
  7. Using StringWriter and IOUtils.copy (Apache Commons)

    StringWriter writer = new StringWriter();
    IOUtils.copy(inputStream, writer, "UTF-8");
    return writer.toString();
  8. Using ByteArrayOutputStream and inputStream.read (JDK)

    ByteArrayOutputStream result = new ByteArrayOutputStream();
    byte[] buffer = new byte[1024];
    int length;
    while ((length = inputStream.read(buffer)) != -1) {
        result.write(buffer, 0, length);
    }
    return result.toString("UTF-8");
  9. Using BufferedReader (JDK). Warning: This solution converts different line breaks (like \n\r) to line.separator system property (for example, in Windows to “\r\n”).

    String newLine = System.getProperty("line.separator");
    BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
    StringBuilder result = new StringBuilder();
    boolean flag = false;
    for (String line; (line = reader.readLine()) != null; ) {
        result.append(flag? newLine: "").append(line);
        flag = true;
    }
    return result.toString();
  10. Using BufferedInputStream and ByteArrayOutputStream (JDK)

    BufferedInputStream bis = new BufferedInputStream(inputStream);
    ByteArrayOutputStream buf = new ByteArrayOutputStream();
    int result = bis.read();
    while(result != -1) {
        buf.write((byte) result);
        result = bis.read();
    }
    return buf.toString("UTF-8");
  11. Using inputStream.read() and StringBuilder (JDK). Warning: This solution has problems with Unicode, for example with Russian text (works correctly only with non-Unicode text)

    int ch;
    StringBuilder sb = new StringBuilder();
    while((ch = inputStream.read()) != -1)
        sb.append((char)ch);
    reset();
    return sb.toString();

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