替换掉字符串中重复的词（只保留一个）

            private string allKeywords = "";
        public string outputKeywords(Model.users users)
        {
            allKeywords += (" "+keywordsOfAge(users.age));
            allKeywords += (" " + keywordsOfSex(users.sex));
            allKeywords += (" " + keywordsOfHightAndWeight(users.hight, users.weight, users.sex));
            allKeywords += (" " + keywordsOfJob(users.job));
            allKeywords += (" " + keywordsOfyylx(users.yylx));
            string[] jj = keywordsOfjj(users.jj).Split(' ');
            for(int i =0;i<jj.Length;i++)
            {
                allKeywords = allKeywords.Replace(jj[i],"");
            }

　　　　　　

//allKeywords中是有可能包含重复词的字符串，而且词之间以空格隔开

            allKeywords = Regex.Replace(allKeywords, "\\s+", " ");//替换掉词之间多余的空格（多于1个空格的替换成一个）

            //开始替换掉重复的关键字
            string[] allKeywords2 =allKeywords.Split(' ');
            ArrayList al = new ArrayList();
            for (int i = 0; i < allKeywords2.Length; i++)
            {
                if (!al.Contains(allKeywords2[i]))
                {
                    al.Add(allKeywords2[i]);
                }
            }
            allKeywords = "";//清理原来的字符串
            for (int i = 0; i < al.Count; i++)
            {
                allKeywords += al[i] + " ";
            }
            return allKeywords;
        }

暂时没想到更简洁的方法