//1.建立Map集合
Map persons=new HashMap(16);//HashMap的預設初始化容量是16，預設載入因子是0.75

//2.儲存鍵值對
persons.put("10000","JACK");
persons.put("10011","JACK");
persons.put("10002","SUN");
persons.put("10003","COOK");
persons.put("10004","KING");
persons.put("10000","LUCY");

//3.判斷鍵值對的個數
//Map中的key是無序不可重複的。和HashSet相同
System.out.println(persons.size());

//4.判斷集合中是否包含這樣的key
System.out.println(persons.containsKey("10000"));//true

//5.判斷結合中是否包含這樣的value
//注意：Map中如果key重複了，value採用的是“覆蓋”
System.out.println(persons.containsValue("LUCY"));//true

//6.通過key獲取value
String k="10001";
Object v=persons.get(k);
System.out.println(v);//SUN

//7.通過key刪除鍵值對
persons.remove("10002");
System.out.println(persons.size());//4

//8.獲取所有的value
Collection values=persons.values();
Iterator it=values.iterator();
while (it.hasNext()){
    System.out.println(it.next());
}

//9.獲取所有的key
//以下程式演示如何遍歷Map集合
Set keys=persons.keySet();
Iterator it2=keys.iterator();
while (it2.hasNext()){
    Object id =it2.next();
    Object name =persons.get(id);
    System.out.println(id+"-->"+name);
}

//10.entrySet
//將Map轉換成Set集合
Set entrySet=persons.entrySet();
Iterator it3=entrySet.iterator();
while (it3.hasNext()){
    System.out.println(it3.next());
}