def _find_java():
        """
        Find location of the java executable (helper for `._launch_server()`).

        This method is not particularly robust, and may require additional tweaking for different platforms...
        :return: Path to the java executable.
        :raises H2OStartupError: if java cannot be found.
        """
        # is java callable directly (doesn't work on windows it seems)?
        java = "java.exe" if sys.platform == "win32" else "java"
        if os.access(java, os.X_OK):
            return java

        # Can Java be found on the PATH?
        for path in os.getenv("PATH").split(os.pathsep):  # not same as os.path.sep!
            full_path = os.path.join(path, java)
            if os.access(full_path, os.X_OK):
                return full_path

        # check if JAVA_HOME is set (for Windows)
        if os.getenv("JAVA_HOME"):
            full_path = os.path.join(os.getenv("JAVA_HOME"), "bin", java)
            if os.path.exists(full_path):
                return full_path

        # check "/Program Files" and "/Program Files (x86)" on Windows
        if sys.platform == "win32":
            # On Windows, backslash on the drive letter is necessary, otherwise os.path.join produces an invalid path
            program_folders = [os.path.join("C:\\", "Program Files", "Java"),
                               os.path.join("C:\\", "Program Files (x86)", "Java"),
                               os.path.join("C:\\", "ProgramData", "Oracle", "Java")]
            for folder in program_folders:
                for dirpath, dirnames, filenames in os.walk(folder):
                    if java in filenames:
                        return os.path.join(dirpath, java)

        # not found...
        raise H2OStartupError("Cannot find Java. Please install the latest JRE from\n"
                              "http://www.oracle.com/technetwork/java/javase/downloads/index.html")
Find location of the java executable (helper for `._launch_server()`).

        This method is not particularly robust, and may require additional tweaking for different platforms...
        :return: Path to the java executable.
        :raises H2OStartupError: if java cannot be found.