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(","); 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; } 会报空指针异常 如何改正

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。