CODEWITHSUNDEEP
javahashmap
user1549861
user1549861

Reputation: 11

iteration over hashmap list

I want to iterate over the HashMap list and retrieve the key and the values (value 1 and value2). There is a error at this line that says "Type mismatch: cannot convert from element type Object to Map.Entry>"

for (Map.Entry<String, List<String>> entry : Map.entrySet())

Am I doing anything wrong. Please help me out. Here is the entire code.

public static void main(String[] args)  {
    Map<String, List<String>> conceptMap = new HashMap<String, List<String>>();
    Map<String, List<String>> PropertyMap = new HashMap<String, List<String>>();
    try{
        Scanner scanner = new Scanner(new FileReader("C:/"));
        while (scanner.hasNextLine()){
            String nextLine = scanner.nextLine();
            String [] column = nextLine.split(":");
            if (column[0].equals ("Property")){
                if (column.length == 4) {
                    PropertyMap.put(column [1], Arrays.asList(column[2], column[3]));    
                }
                else {
                    conceptMap.put (column [1], Arrays.asList (column[2], column[3]));
                }
            }
            for (Map.Entry<String, List<String>> entry : Map.entrySet()) {
                String key = entry.getKey();
                List<String> valueList = entry.getValue();
                System.out.println("Key: " + key);
                System.out.print("Values: ");
                for (String s : valueList) {
                    System.out.print(s + " ");
                }
            }
        }

        scanner.close();
    }    
    catch (Exception e) {
        e.printStackTrace();
    }

Upvotes: 0

Views: 828

Answers (3)

userj19
userj19

Reputation: 1

Map.entrySet() returns a collection view of the map.change it in to conceptMap.entrySet() or propertyMap.entrySet

Upvotes: 0

SteveZissou
SteveZissou

Reputation: 53

Change Map.entrySet() to PropertyMap.entrySet() or conceptMap.entrySet()

Upvotes: 2

Chris Dargis
Chris Dargis

Reputation: 6053

The Map.entrySet() method declared by the Map interface returns a collection-view of the map (returns a Set). Each of these set elements is a Map.Entry object. The only way to obtain a reference to a map entry is from the iterator of this collection-view.

If you want to return a Set you inserted into the map, you have to call it on the Collection you placed it in:

PropertyMap.entrySet() and conceptMap.entrySet() will return Sets.

Map.entrySet() is not calling the method on either of your instantiated Maps.

Upvotes: 1

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