What are the main methods and operations that can be performed on Map data structures?

In Android (and Java in general), the Map data structure represents a collection of key-value pairs. The main methods and operations on Map include:

• put(K key, V value) — adds or updates a key-value pair.
• get(Object key) — returns the value for the key or null if the key is absent.
• remove(Object key) — removes the pair by key.
• containsKey(Object key) — checks for the presence of a key.
• containsValue(Object value) — checks for the presence of a value.
• keySet() — returns a set of all keys.
• values() — returns a collection of all values.
• entrySet() — returns a set of all key-value pairs.
• size() — the number of elements in the Map.
• clear() — clears the Map.

Example usage:

Map<String, Integer> map = new HashMap<>();
map.put("apple", 3);
map.put("banana", 5);

int count = map.get("apple"); // 3

if (map.containsKey("banana")) {
    map.remove("banana");
}

for (String key : map.keySet()) {
    System.out.println(key + ": " + map.get(key));
}