如何在 recyclerview 上计算相同的值？

Question

Is there any method for counting the occurrence of each item on recyclerview?

Lets say I have recyclerview items:

String[] array = {"item1","item1","item2","item2", "item3", "item4"};

expected output:-

item1  2
item2  2
item3  1
item4  1

I already create recycleview adapter, but i don't know how to count the same item. please help

Answer 1

Here is the function you are looking for

public void countEntries(String[] items) {
    HashMap itemToCountMap = new HashMap<String, Integer>();
    for (String item : items) {
        if (itemToCountMap.containsKey(item)) {
            Integer current = (Integer) itemToCountMap.get(item);
            itemToCountMap.put(item, current + 1);
        } else {
            itemToCountMap.put(item, 1);
        }
    }

    // Key - is the string
    // Value - is the number of repetitions
    itemToCountMap.forEach((key, value) -> System.out.println("key: "+key+" value:"+value));
}

Now you only need to get items from the recyclerView.adapter (if your items are public)

String[] items = recyclerView.getAdapter().getItems()
countEntries(items)