??????????????java?е?Map????key->value?????洢??????????Map???????????Map?? ??????????Key???????????value?????????????????仰?????????Map??Key??????value????Map???????????????? ??????????Map?????????????????У????????Map?????????HashMap??TreeMap?????????Map???????????????????? Ч?????????????HashMap????????????????????Key????????????TreeMap??????TreeMap????????????????????????????
??????Key????????
??????????????????TreeMap????
????Map<Integer?? Person> map = new TreeMap<Integer?? Person>();
?????????map???????????????????????????????map?????????????????
//????????
for (Iterator<Integer> it = map.keySet().iterator(); it.hasNext();) {
Person person = map.get(it.next());
System.out.println(person.getId_card() + " " + person.getName());
}
????????????????????HashMap????????HashMap???????TreeMap?????￡?
????Map<Integer?? Person> map = new HashMap<Integer?? Person>();
????TreeMap treemap = new TreeMap(map);
??????Value????????
?????????????HashMap????
????Map<String?? Integer> map = new HashMap<String?? Integer>();
???????????????Map?????????List?????У???List???ArrayList????????￡?
????List<Entry<String??Integer>> list =
????new ArrayList<Entry<String??Integer>>(map.entrySet());
?????????Collections.sort(List l?? Comparator c)?????????????????????￡?
Collections.sort(list?? new Comparator<Map.Entry<String?? Integer>>() {
public int compare(Map.Entry<String?? Integer> o1??
Map.Entry<String?? Integer> o2) {
return (o2.getValue() - o1.getValue());
}
});
???????????????map?е?value????????????????????????????????????????????o2.getValue() - o1.getValue()?o1.getValue() - o2.getValue()????