### Question:
TopN { public static long[] top(Collection<? extends VectorInterface> vectorItems, int n) { VectorInterface[] vectors = getVectors(vectorItems); return top(vectors, n); }  static long[] top(Collection<? extends VectorInterface> vectorItems, int n);  }### Answer:
@Test public void testTopN() { Map<String, ? extends VectorInterface> vectorMap = getAllVectorMap(); for (int column = -1; column >= 0; column--) { ApiLogger.debug(column); } long[] result = TopN.top(vectorMap.values(), 20); ApiLogger.debug("result length:" + result.length + ", result" + Arrays.toString(result)); result = TopN.top(vectorMap.values(), 30); ApiLogger.debug("result length:" + result.length + ", result" + Arrays.toString(result)); result = TopN.top(vectorMap.values(), CommonConst.TIMELINE_SIZE); ApiLogger.debug("result length:" + result.length + ", result" + Arrays.toString(result)); }