具有来自List<List<String>>的频率计数的唯一值

import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class FrequencyCounter {
    public static Map<String, Integer> getUniqueValueFrequency(List<List<String>> data) {
        Map<String, Integer> frequencyMap = new HashMap<>();

        for (List<String> subList : data) {
            for (String value : subList) {
                frequencyMap.put(value, frequencyMap.getOrDefault(value, 0) + 1);
            }
        }

        return frequencyMap;
    }

    public static void main(String[] args) {
        List<List<String>> data = List.of(
                List.of("a", "b", "c"),
                List.of("a", "b", "d"),
                List.of("c", "d", "e")
        );

        Map<String, Integer> frequencyMap = getUniqueValueFrequency(data);

        for (Map.Entry<String, Integer> entry : frequencyMap.entrySet()) {
            System.out.println("Value: " + entry.getKey() + ", Frequency: " + entry.getValue());
        }
    }
}