java实现一个自定义排序

 

java中List排序 例子
 
package test;
 
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
 
public class Test {
 
    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO 自動生成されたメソッド・スタブ
        List<Map<String,Object>> list = new ArrayList<Map<String,Object>>();
        Map<String,Object> m1 = new HashMap<String,Object>();
        m1.put("NO", 2);
        m1.put("NO1", "2");
        m1.put("NO2", "f");
        list.add(m1);
        Map<String,Object> m2 = new HashMap<String,Object>();
        m2.put("NO", 1);
        m2.put("NO1", "10");
        m2.put("NO2", "z");
        list.add(m2);        
        Map<String,Object> m3 = new HashMap<String,Object>();
        m3.put("NO", 1);
        m3.put("NO1", "10");
        m3.put("NO2", "a");
        list.add(m3);
 
        Test test = new Test();
        test.getSortedList(list,new String[]{"NO","NO1","NO2"});
        System.out.println(list);
        
    }
    
    private void getSortedList(List<Map<String, Object>> list, String[] pros) {
 
        if (pros.length <= 0)
            return;
        for (int i = pros.length - 1; i >= 0; i--) {
            final String pro = pros[i];
            try {
                Collections.sort(list, new Comparator<Map<String, Object>>() {
                    String name = "get";
                    Method method = Map.class.getMethod(name, new Class[] {Object.class});
 
                    public int compare(Map<String, Object> a, Map<String, Object> b) {
                        if (a == null || b == null) {
                            return 0;
                        } else {
                            int flag = 0;
                            try {
 
                                Object as = method.invoke(a, new Object[] {pro});
                                Object bs = method.invoke(b, new Object[] {pro});
                                if (as == null && bs == null)
                                    return 0;
                                else if (as == null)
                                    return -1;
                                else if (bs == null)
                                    return 1;
                                else {
                                    if (as instanceof Integer) {                                        
                                        Integer va = (Integer) as;
                                        Integer vb = (Integer) bs;
                                        flag = va.compareTo(vb);
                                    }else if (as instanceof String) {
                                        String va = (String) as;
                                        String vb = (String) bs;
                                        flag = va.compareTo(vb);
                                    }
                                }
                            } catch (IllegalArgumentException e) {
                                System.out.println("e1");
                            } catch (IllegalAccessException e) {
                                System.out.println("e2");
                            } catch (InvocationTargetException e) {
                                System.out.println("e3");
                            }
                            return flag;
                        }
                    }
                });
            } catch (NoSuchMethodException e) {
                //TODO Auto-generated catch block 
                e.printStackTrace();
            }
        }
    }
}
执行结果：
[{NO=1, NO2=a, NO1=10}, {NO=1, NO2=z, NO1=10}, {NO=2, NO2=f, NO1=2}]