java list 排序,null 情况,通用

转载：http://www.cnblogs.com/Bob-FD/archive/2012/09/21/2697275.html

//SortList.java
package test;

import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;
/**
* @author jardot
* @version 1.0
* 通用排序
*/
public class SortList<E>{    
    public void Sort(List<E> list, final String method, final String sort){
        Collections.sort(list, new Comparator() {            
            public int compare(Object a, Object b) {
                int ret = 0;
                try{
                    Method m1 = ((E)a).getClass().getMethod(method, null);
                    Method m2 = ((E)b).getClass().getMethod(method, null);
                    if(sort != null && "desc".equals(sort))//倒序
                        ret = m2.invoke(((E)b), null).toString().compareTo(m1.invoke(((E)a), null).toString());    
                    else//正序
                        ret = m1.invoke(((E)a), null).toString().compareTo(m2.invoke(((E)b), null).toString());
                }catch(NoSuchMethodException ne){
                    System.out.println(ne);
                }catch(IllegalAccessException ie){
                    System.out.println(ie);
                }catch(InvocationTargetException it){
                    System.out.println(it);
                }
                return ret;
            }
         });
    }
}

 

  Collections.sort(users, new Comparator<ActiveUser>() {
            @Override
            public int compare(ActiveUser o1, ActiveUser o2) {
                return CompareToBuilder.reflectionCompare(o1, o2, new String[] {"userId","name"});
            }
            
        });

 

 

调用方法：

//Test.java
package test;

import java.util.ArrayList;
import java.util.List;
import java.text.SimpleDateFormat;

public class Test {

    public static void main(String[] args)throws Exception{
        List<UserInfo> list = new ArrayList<UserInfo>();
        
        SimpleDateFormat formater = new SimpleDateFormat("yyyy-MM-dd");
        
        list.add(new UserInfo(3,"b",formater.parse("1980-12-01"),11));
        list.add(new UserInfo(1,"c",formater.parse("1980-10-01"),30));
        list.add(new UserInfo(2,"a",formater.parse("1973-10-01"),11));
                    
        System.out.println("-------原来序列-------------------");
        for(UserInfo user : list){
            System.out.println(user.toString());
        }        
        
        //调用排序通用类
        SortList<UserInfo> sortList = new SortList<UserInfo>();
        
        //按userId排序
        sortList.Sort(list, "getUserId", "desc");
        System.out.println("--------按userId倒序------------------");
        for(UserInfo user : list){
            System.out.println(user.toString());
        }
        
        //按username排序
        sortList.Sort(list, "getUsername", null);
        System.out.println("---------按username排序-----------------");        
        for(UserInfo user : list){
            System.out.println(user.toString());
        }
        
        //按birthDate排序
        sortList.Sort(list, "getBirthDatestr", null);
        System.out.println("---------按birthDate排序-----------------");        
        for(UserInfo user : list){
            System.out.println(user.toString());
        }
    }

}