初始化一個Map <富，矢量<Bar>> - Java 7的

Question

我需要初始化一個像Map x<Apartment,Vector<Expense>>它可以讓我，如果我@override地圖方法

Description Resource Path Location Type 
The type new Map<Apartment,Vector<Expense>>(){} must implement the inherited abstract method Map<Apartment,Vector<Expense>>.isEmpty() Repository.java /proj_individual/src/repo line 12 Java Problem 
The type new Map<Apartment,Vector<Expense>>(){} must implement the inherited abstract method Map<Apartment,Vector<Expense>>.size() Repository.java /proj_individual/src/repo line 12 Java Problem 
The type new Map<Apartment,Vector<Expense>>(){} must implement the inherited abstract method Map<Apartment,Vector<Expense>>.keySet() Repository.java /proj_individual/src/repo line 12 Java Problem 
The type new Map<Apartment,Vector<Expense>>(){} must implement the inherited abstract method Map<Apartment,Vector<Expense>>.remove(Object) Repository.java /proj_individual/src/repo line 12 Java Problem 
The type new Map<Apartment,Vector<Expense>>(){} must implement the inherited abstract method Map<Apartment,Vector<Expense>>.entrySet() Repository.java /proj_individual/src/repo line 12 Java Problem 
The type new Map<Apartment,Vector<Expense>>(){} must implement the inherited abstract method Map<Apartment,Vector<Expense>>.putAll(Map<? extends Apartment,? extends Vector<Expense>>) Repository.java /proj_individual/src/repo line 12 Java Problem 
The type new Map<Apartment,Vector<Expense>>(){} must implement the inherited abstract method Map<Apartment,Vector<Expense>>.values() Repository.java /proj_individual/src/repo line 12 Java Problem 
The type new Map<Apartment,Vector<Expense>>(){} must implement the inherited abstract method Map<Apartment,Vector<Expense>>.clear() Repository.java /proj_individual/src/repo line 12 Java Problem 
The type new Map<Apartment,Vector<Expense>>(){} must implement the inherited abstract method Map<Apartment,Vector<Expense>>.get(Object) Repository.java /proj_individual/src/repo line 12 Java Problem 
The type new Map<Apartment,Vector<Expense>>(){} must implement the inherited abstract method Map<Apartment,Vector<Expense>>.containsKey(Object) Repository.java /proj_individual/src/repo line 12 Java Problem 
The type new Map<Apartment,Vector<Expense>>(){} must implement the inherited abstract method Map<Apartment,Vector<Expense>>.containsValue(Object) Repository.java /proj_individual/src/repo line 12 Java Problem 
The type new Map<Apartment,Vector<Expense>>(){} must implement the inherited abstract method Map<Apartment,Vector<Expense>>.put(Apartment, Vector<Expense>) Repository.java /proj_individual/src/repo line 12 Java Problem 

但我在互聯網上閱讀地圖不是接口，它是一個類，我做錯了，或者這是必須完成的方式？

Answer 1

Map<Apartment, Vector<Expense>> map = new HashMap<Apartment, Vector<Expense>>(); 

Map是一個接口（如the javadoc說— javadoc的應該是你的參考，而不是互聯網）。你需要選擇一個實現（HashMap是最常用的實現，但還有其他實現，以及其他特性）。

你也應該忘記Vector。它不應該被使用了。使用List作爲一個類型，和ArrayList作爲實現（也有其他的List實現，但ArrayList中幾乎總是你想要的）：

Map<Apartment, List<Expense>> map = new HashMap<Apartment, List<Expense>>(); 

或者乾脆

Map<Apartment, List<Expense>> map = new HashMap<>(); 

，如果你是下Java 7中

Answer 2

請點擊這裏：http://docs.oracle.com/javase/6/docs/api/java/util/Map.html

您可以使用HashMap實例。

Answer 3

不過，我看到在互聯網上說地圖是不是一個接口

約一門編程語言永遠是官方文檔信息的最佳場所。說到java，只要確保先看看：http://docs.oracle.com/javase/7/docs/

Map是一個接口。從Java文檔API：

將鍵映射到值的對象。地圖不能包含重複的鍵;每個鍵可以映射到最多一個值。 這個接口取代了Dictionary類，它是一個完全抽象的類而不是接口。

我建議您使用其中一個實施類，如HashMap。從Java API文檔：

基於哈希表的Map實現的接口。該實現提供了所有可選的映射操作，並允許使用空值和空鍵。 （HashMap類大致等同於Hashtable，除了它是不同步的並且允許爲空值。）這個類不能保證地圖的順序;特別是，它不能保證訂單會隨着時間的推移保持不變。

您的代碼可以通過簡單地更換Map爲HashMap在被然後是功能：

new HashMap<Apartment,Vector<Expense>> 

我希望它幫助。乾杯