排序大汇总

对list按某个属性进行排序

 Collections.sort(list,new Comparator() {
		      public int compare(Object o1, Object o2) {
		    	  Person v1=(Person) o1;
		    	  Person v2=(Person) o2;
		        return v1.getPrice().compareTo(v2.getPrice());
		      }
});

对Map进行排序

	/**
     * 使用 Map按key进行排序
     * @param map
     * @return
     */
    public static Map<String, String> sortMapByKey(Map<String, String> map) {
        if (map == null || map.isEmpty()) {
            return null;
        }

        Map<String, String> sortMap = new TreeMap<String, String>(new MapKeyComparator());

        sortMap.putAll(map);

        return sortMap;
}


Map<String, Integer> map =new TreeMap<String	, Integer>();
map.put("a", 1);
map.put("b", 2);
map.put("c", 3);
System.out.println(map);	//{a=1, b=2, c=3}
Collection<Integer> values = map.values();
System.out.println(values);	//[1, 2, 3]
Set keySet = map.keySet();
System.out.println(keySet);	//[a, b, c]