- /*
- Map集合被使用是因为具备映射关系。
- */
- import java.util.*;
- class Province
- {
- private int id;
- private String name;
- Province(int id,String name)
- {
- this.id =id;
- this.name =name;
- }
- public String getInfo()
- {
- return id+":::"+name;
- }
- }
- class Test
- {
- public static void main(String [] args)
- {
- HashMap<Integer,List<Province>> hm =new HashMap<Integer,List<Province>>();
-
- List<Province> CHN =new ArrayList<Province>();
- List<Province> USA =new ArrayList<Province>();
- List<Province> ENG =new ArrayList<Province>();
-
- hm.put(1,CHN);
- hm.put(2,USA);
- hm.put(3,ENG);
- CHN.add(new Province(1,"cd"));
- CHN.add(new Province(2,"cs"));
- CHN.add(new Province(3,"cj"));
- USA.add(new Province(2,"us"));
- USA.add(new Province(3,"ub"));
- USA.add(new Province(1,"ua"));
- ENG.add(new Province(3,"ee"));
- ENG.add(new Province(1,"ea"));
- ENG.add(new Province(2,"ez"));
-
- //entrySet():返回此映射所包含的映射关系的 Set 视图。
- //Set<Map.Entry<Integer,String>> me =hm.entrySet(); Set<Map.Entry<K,V>>
- /*for (Iterator<Map.Entry<Integer,List<Province>>> it =hm.entrySet().iterator();it.hasNext() ; )
- {
- Map.Entry<Integer,List<Province>> me =it.next();
- Integer key=me.getKey();
- List<Province> value =me.getValue();
-
- sop(getCountryInfo(value));
- }
- //keySet();返回此映射中所包含的键的 Set 视图。 Set<K>
- /*for (Iterator<Integer> it =hm.keySet().iterator(); it.hasNext(); )
- {
- Integer key =it.next();
- String value =hm.get(key);
- sop(key+"::::"+value);
- }
- */
- for (Iterator<Integer> it =hm.keySet().iterator(); it.hasNext(); )
- {
- Integer key =it.next();
- List<Province> value=hm.get(key);
- sop(getCountryInfo(value));
- }
-
- }
- public static String getCountryInfo(List<Province> value)
- {
- StringBuffer sb =new StringBuffer();
- Iterator<Province> it =value.iterator();
- for (;it.hasNext() ; )
- {
- Province p =it.next();
- sb.append(p.getInfo()+"\t");
- }
- return sb.toString();
- }
- public static void sop(Object obj)
- {
- System.out.println(obj);
- }
- }
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