List sumList=new ArrayList(); 
for(int i=0;i<10;i++){
        //执行sql,获取一个包含10W个TxtClass对象 
        Sql1 = .....................100000;
             List tmpList =  10W个TxtClass对象;
             sumList.add(tmpList);
     }
 
for(int i=0;i<10;i++){
        //执行sql,获取一个包含10W个TxtClass对象 
        Sql2 = .....................100000;
             List tmpList =  10W个txtClass对象;
             sumList.add(tmpList);
     } 
 int sumSize = sumList.size();
 StringBuffer _sb = new StringBuffer();
 List finalList=new ArrayList();             
 
 for(int i=0;i<sumSize;i++){
     List tmpList = (List)sumList.get(i);
     int tmpSize = tmpList.size();
     List finaTmplList=new ArrayList();            
     for(int j=0;j<sumSize;j++){
         TxtClass tmpTxtClass = (TxtClass)tmpList.get(i);
         String strId = tmpTxtClass.getId();
         _sb.append(strId+",");
         if(_sb.toString().indexOf(strId+",")<0){
             //如果该ID从来没有存在过则用tmpTxtClass对象内容生成文件
             writeFile(tmpTxtClass);                        
             finaTmplList.add(tmpTxtClass);
         }
     }
     finalList.add(finaTmplList);
     //最后再将合并的List当做对象传给其他方法
     xxxClass.xxxMethod(finalList);
     
 }