优化这段代码 list=map.get(s1[0]); list2=map.get(s1[0]); for(int j=1;j<s1.length;j++) { list1=map.get(s1[j]); for(Integer n:list2) { if(!list1.contains(n)) list.remove(n); } }

可以在代码中加入对 `s2` 是否为 `null` 的判断，如下所示： ``` public static List<Map<String, Object>> hour(List<Map<String, Object>> list) { if (list != null && list.size() > 0) { String item = ""; String[] s1 = null; for (Map<String, Object> m : list) { item = m.get("item_info").toString(); s1 = item.split(";"); for (String s : s1) { String[] s2 = null; s2 = s.split(","); if (s2 != null && s2.length > 2) { m.put(s2[0], s2[2]); m.put(s2[0] + "code", s2[0]); m.put(s2[0] + "detname", s2[3]); if (s2.length >= 5) { m.put(s2[0] + "bzz", s2[4]); } if (s2.length >= 6) { m.put(s2[0] + "yj", s2[5]); } if (s2.length >= 7) { m.put(s2[0] + "bj", s2[6]); } if (s2.length >= 8) { m.put(s2[0] + "dw", s2[7]); } } } } } return list; } ``` 在对 `s2` 进行操作前，加入了 `s2 != null && s2.length > 2` 的判断，确保了 `s2` 不为 `null` 且至少有 3 个元素，避免了空指针异常的发生。

这段代码中有重复的逻辑，可以抽象成一个方法，减少重复代码。同时，可以使用 Java 8 的 Optional 等新特性简化代码。具体来说，可以将以下部分重构： ``` GoodsExplosive explosive = null; List<GoodsExplosive> explosives = new GoodsExplosive().selectList(new LambdaUpdateWrapper<GoodsExplosive>() .eq(GoodsExplosive::getGoodsItemId, goodsItem.getId()) .orderByDesc(GoodsExplosive::getId)); if (explosives.size() > 1) { explosive = explosives.stream().sorted(Comparator.comparing(GoodsExplosive::getGroundingState, (s1, s2) -> { if (s1.equals(s2)) { return 0; } else if (s1 == 1 || s2 == 5) { return -1; } else if (s1 == 5 || s2 == 1) { return 1; } else if (s1 == 2) { return -1; } else if (s2 == 2) { return 1; } else if (s1 == 0) { return -1; } else { return 1; } })).findFirst().orElse(null); } else { explosive = explosives.size() == 1 ? explosives.get(0) : explosive; } ``` 可以抽象成一个方法： ``` private Optional<GoodsExplosive> getGoodsExplosive(GoodsItem goodsItem) { List<GoodsExplosive> explosives = new GoodsExplosive().selectList(new LambdaUpdateWrapper<GoodsExplosive>() .eq(GoodsExplosive::getGoodsItemId, goodsItem.getId()) .orderByDesc(GoodsExplosive::getId)); return explosives.stream().sorted(Comparator.comparing(GoodsExplosive::getGroundingState, (s1, s2) -> { if (s1.equals(s2)) { return 0; } else if (s1 == 1 || s2 == 5) { return -1; } else if (s1 == 5 || s2 == 1) { return 1; } else if (s1 == 2) { return -1; } else if (s2 == 2) { return 1; } else if (s1 == 0) { return -1; } else { return 1; } })).findFirst(); } ``` 然后可以简化 switch 语句： ``` switch (goodsItem.getProductType()) { case 1: //爆品 map.put("productData", getGoodsExplosive(goodsItem).orElse(null)); break; case 2: //精品 map.put("productData", new GoodsExcellent().selectList(new LambdaUpdateWrapper<GoodsExcellent>() .eq(GoodsExcellent::getGoodsItemId, goodsItem.getId()) .orderByDesc(GoodsExcellent::getId)) .stream().findFirst().orElse(null)); break; case 3: //现货 map.put("productData", new GoodsEnjoy().selectList(new LambdaUpdateWrapper<GoodsEnjoy>() .eq(GoodsEnjoy::getGoodsItemId, goodsItem.getId()) .orderByDesc(GoodsEnjoy::getId)) .stream().findFirst().orElse(null)); break; default: throw new IllegalStateException("Unexpected value: " + goodsItem.getProductType()); } ```