1 /** 2      * 按给定对象属性为参数ls分组整理 3      * @param ls 集合 4      * @param propertyName 对象中的某个属性 5      * @return HashMap(key=propertyValue,Value=ArrayList) 6      * @throws IllegalAccessException 7      * @throws InvocationTargetException 8      * @throws NoSuchMethodException 9      */10     @SuppressWarnings("unchecked")11     public static 
     
       HashMap
      
       
        > groupByProperty(List
        
          ls,String propertyName) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException{12         HashMap
         
          
           > result=new HashMap
           
            
             >();13 List
             
               list=null;14 for (Iterator
              
                iter = ls.iterator(); iter.hasNext();) {15 E element = iter.next();16 T proValue=(T)PropertyUtils.getProperty(element, propertyName);17 if(proValue==null)18 throw new NullPointerException("propertyValue is null"); 19 if(result.containsKey(proValue)){20 list=(List
               
                ) result.get(proValue);21 }else{22 list=new ArrayList
                
                 ();23 result.put(proValue, list);24 }25 list.add(element);26 }27 return result;28 }
                
               
              
             
            
           
          
         
        
       
      
     

 

1     /** 2      * 提取集合中的对象的属性,组合成List. 3      *  4      * @param collection 来源集合. 5      * @param propertyName 要提取的属性名. 6      */ 7     @SuppressWarnings({ "unchecked", "rawtypes" }) 8     public static List fetchElementPropertyToList(final Collection collection, final String propertyName) throws Exception {10         List list = new ArrayList();11         for (Object obj : collection) {12             list.add(PropertyUtils.getProperty(obj, propertyName));13         }14 15         return list;16     }