public static void writeString(String s, DataOutput out) throws IOException {
        if(s != null) {
            out.write(1);
            out.writeUTF(s);
        }
        else
            out.write(0);
    }
public static void writeString ( String s , DataOutput out ) throws IOException { if ( s != null ) { out . write ( 1 ) ; out . writeUTF ( s ) ; } else out . write ( 0 ) ; }
Writes a string to buf. The length of the string is written first, followed by the chars (as single-byte values).
Multi-byte values are truncated: only the lower byte of each multi-byte char is written, similar to
{@link DataOutput#writeChars(String)}.
@param s the string
@param out the output stream