判断是不是重复

判断是否重复
一个集合中是否有重复数据

public String getCdbmj(List<Xmfp> lis)
  {
    Map map = new HashMap();
    String mp = null;
    for (int i = 0; i < lis.size(); ++i) {
      Xmfp xmfp = (Xmfp)lis.get(i);
      String[] cds = xmfp.getCdbmj().split(",");
      for (int j = 0; j < cds.length; ++j)
        if (!(map.containsKey(cds[j])))
          map.put(cds[j], cds[j]);


    }

    Set keys = map.keySet();
    for (Iterator iter = keys.iterator(); iter.hasNext(); ) {
      String val = (String)iter.next();
      if (mp == null) {
        mp = val;
      }else{
      mp = mp + "," + val;
      }
    
    }

    return mp;
  }