public Object[][] randomRows(int n) {

    final Object[][] result = new Object[n][];
    for (int i = 0; i < n; i++) {
      result[i] = randomRow();
    }
    return result;
  }
Generate object inspector and random row object[].
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/VectorRandomRowSource.java