public static String toString(boolean[] a) {
    if (a == null) return "null";
    StringBuilder b = new StringBuilder();
    b.append('[');
    for (int i = 0; i < a.length; ++i) {
      b.append(a[i] ? "1" : "0");
    }
    b.append(']');
    return b.toString();
  }
A class that contains debug methods; also allows enabling the logging of various
trace messages with low runtime cost, in order to investigate reproducible bugs.
ql/src/java/org/apache/hadoop/hive/llap/DebugUtils.java