CODEWITHSUNDEEP
java
aquib nawaz
aquib nawaz

Reputation: 89

Map as a function parameter in java

I am writing a function which takes two map as argument
Here is my code

    public static Map<String, ArrayList<String> > getFavouriteGenres(Map<String, ArrayList<String> > userMovies, Map<String, ArrayList<String> > movieGenres)
    {
        
        Map<String, ArrayList<String>> genreMovies = new HashMap<String, ArrayList<String>>();

        for (Map.Entry m:movieGenres.entrySet()){
            //ArrayList<String> list = m.getValue();  
            for (String mov:m.getValue()){
                ArrayList<String> l = genreMovies.containsKey(mov) ? genreMovies.get(mov):new ArrayList<String>();
                genreMovies.put(mov, l.add(m.getKey()));
            }                            
        }
    //other implementation

On compilation I am getting following error

StreamingApp.java:17: error: for-each not applicable to expression type
            for (String mov:m.getValue()){
                                      ^
  required: array or java.lang.Iterable
  found:    Object
StreamingApp.java:19: error: incompatible types: Object cannot be converted to String
                genreMovies.put(mov, l.add(m.getKey()));

How to solve it ?

Upvotes: 0

Views: 121

Answers (2)

Monis
Monis

Reputation: 1008

Change

for (Map.Entry m:movieGenres.entrySet()){

TO

for (Map.Entry<String, ArrayList<String>> m:movieGenres.entrySet()){

AND

genreMovies.put(mov, l.add(m.getKey()));

TO

l.add(m.getKey());
genreMovies.put(mov, l);

Upvotes: 1

rzwitserloot
rzwitserloot

Reputation: 103263

You are using Map.Entry as a raw type. That means all generics of it and anything derived from it are also blank. Thus, m.getValue() returns Object and not ArrayList<String>.

The solution is to add the generics appropriately:

for (Map.Entry<String, ArrayList<String>> m : movieGenres.entrySet()) {
    List<String> list = m.getValue();
   ...
}

that's a mouthful. Fortunately, you can write that a lot more simply:

for (var m : movieGenries.entrySet()) {
    List<String> list = m.getValue();
    ...
}

Upvotes: 3

Related Questions