Use ArrayList e HashMap na prática

1import java.util.ArrayList;
2import java.util.HashMap;
3
4ArrayList<String> regions = new ArrayList<>();
5regions.add("north");
6regions.add("south");
7regions.add("north");
8
9HashMap<String, Integer> counts = new HashMap<>();
10for (String region : regions) {
11    counts.put(region, counts.getOrDefault(region, 0) + 1);
12}
13
14System.out.println(counts.get("north"));