Java tutorial
//package com.java2s; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.IOException; public class Main { private static boolean isRootOk(DataOutputStream output, DataInputStream input, final DataInputStream errInput) { if (output != null) { try { output.writeBytes("id\n"); output.flush(); String a = input.readLine(); if (a.contains("root") || a.contains("uid=0")) { return true; } new Thread() { @Override public void run() { try { errInput.read(); } catch (IOException e) { e.printStackTrace(); } }; }.start(); } catch (IOException e) { e.printStackTrace(); } } return false; } }