How to test if a value is already in my HashMap while reading a file

I am working currently on a program to find similar sets so i need to map all my items contained in many sets in a HashMap with key,value pairs but i don't want redundant items to have many keys like key=1 value=bread and key=2 value=bread

So I wrote the following code

public static void main(String[] args) throws FileNotFoundException, IOException {
    // HashMap to stock all my items with keys that i will use for minhashing
    HashMap<Integer,String> hmap= new HashMap<>();
    List<List<Integer>> MinHash = new ArrayList<>();

    //to read my sets that i defined 
    FileReader in=new FileReader("C:\\items\\items.txt");
    BufferedReader brr = new BufferedReader(in);
    String item ; 
    int key=1; //for checking value pairs
    while( (item = brr.readLine()) != null)
        {
            System.out.println(hmap.containsValue(item));
            if(hmap.containsValue(item))//problem
                System.out.println("Item already in my map");
            else{
            hmap.put(key, item);
            key++;
            }
        }
    System.out.print(hmap);
}

But this test doesn't seem to return value true even if i have already this value in my HashMap