JAVA的split的用法

public List<Object[]> getRepertoryList(String tid){
    StringBuffer bf=new StringBuffer();
    bf.append("select t.id,t.name from Reper where 1=1") ;  
    if(StringUtils.isNotEmpty(tid)&&tid!="undefined"){
         String ids="";
         String [] sp=tid.split(",");
         for(int i=0;i<sp.length;i++) {  
             if(i==sp.length-1){
                   ids+="'"+sp[i]+"'";
              }else{
                  ids+="'"+sp[i]+"',";
             }
           }
           bf.append(" and t.Demp in(" +ids+")")
    }
     
      List<Object[]> list =(List<Object[]>)baseDAO.getListBySql(bf.toString());

if(list !=null && list.size()>0){
  return list; 
}
   return null;

}