Question

I need to initialize a like Map x<Apartment,Vector<Expense>> it allows me if I @override the Map methods

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

But I read on the internet that Map isn’t a interface, it is a class, am I doing it wrong, or this is the way it has to be done?

Answer 1

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

Map is an interface (as the javadoc says — javadoc should be your reference, rather than the Internet). You need to choose an implementation (HashMap being the most often used one, but there are other implementations, with other characteristics).

You should also forget about Vector. It shouldn’t be used anymore. Use List as a type, and ArrayList as an implementation (there are also other List implementations, but ArrayList is almost always what you want):

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

or simply

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

if you’re under Java 7.