Basic operations on maps
Map is quite different from the other collections. Let’s learn how to perform the basic operations on Map.
Adding elements to a map
There is no add() method for Map. We can add elements to a Map interface using the put() method:
Map<String, Integer> gfNrMap = new HashMap<>();gfNrMap.put("Ross", 12);
gfNrMap.put("Chandler", 8);
This adds two key-value pairs to Map. Let’s see how we can get the values out again.
Getting elements from a map
We can get elements from a Map interface using the get() method. This is how we can get the Integer value associated with the Ross key:
int rossNrOfGfs = gfNrMap.get("Ross"); We can also use the key to modify the values of the map.
Changing the elements of a map
We can change the elements in a Map interface using the put() method with an existing key:
gfNrMap.put("Chandler", 9); The preceding code changes the value of 8 to 9...