"java -version" command result in error stream

Question

i am getting output of following command in error stream instead of input stream

Runtime rt = Runtime.getRuntime();
ProcessBuilder builder = new ProcessBuilder(new String[]{"cmd.exe","/c","java -version"});
Process pr =   builder.start();
BufferedReader input = new BufferedReader(new InputStreamReader(pr.getErrorStream()));
String line=input.readLine();
System.out.println(line);

please explain

Answer 1

Clearly, Java sends the version string into stderr. This is not a very uncommon practice because it is not the output of the client code. Don't be mislead by the name ErrorStream: it is used for much more than errors; it is basically a signalling side-channel beside the main one, which is stdout.

Answer 2

It works file in jdk7

    public static void main(String[] args) throws Exception {
        Runtime rt = Runtime.getRuntime();
        ProcessBuilder builder = new ProcessBuilder(new String[]{"cmd.exe","/c","java -version"});
        Process pr =   builder.start();
        BufferedReader input = new BufferedReader(new InputStreamReader(pr.getErrorStream()));
        String line=input.readLine();
        System.out.println(line);

    }