How do I convert an InputStream to a String in Java?

Question

Suppose I have an InputStream that contains text data, and I want to convert this to a String (for example, so I can write the contents of the stream to a log file).

What is the easiest way to take the InputStream and convert it to a String?

public String convertStreamToString(InputStream is) { 
    // ???
}

Answer 1

You can use a BufferedReader to read the stream into a StringBuilder in a loop, and then get the full contents from the StringBuilder:

public String convertStreamToString(InputStream is) { 
  BufferedReader reader = new BufferedReader(new InputStreamReader(is)); 
  StringBuilder sb = new StringBuilder(); 

  String line = null; 

  try { 
    while ((line = reader.readLine()) != null) { 
    sb.append(line + "\n"); 
    } 
  } catch (IOException e) { 
    e.printStackTrace(); 
  } finally { 
    try { 
      is.close(); 
    } catch (IOException e) { 
      e.printStackTrace(); 
    } 
  }

  return sb.toString(); 
}

Full disclosure: This is a solution I found on KodeJava.org. I am posting it here for comments and critique.

Answer 2

If you want to do it simply and reliably, I suggest using the Apache Jakarta Commons IO library IOUtils.toString(java.io.InputStream) method.

Answer 3

This is my version,

public static String readString(InputStream inputStream) throws IOException {

    ByteArrayOutputStream into = new ByteArrayOutputStream();
    byte[] buf = new byte[4096];
    for (int n; 0 < (n = inputStream.read(buf));) {
        into.write(buf, 0, n);
    }
    into.close();
    return new String(into.toByteArray(), "UTF-8"); // Or whatever encoding
}

Answer 4

String text = new Scanner( inputStream).useDelimiter("\\A").next();

more here