java - 获取 LinkedHashMap 中每个条目的最后一个元素？

Question

我有一个 map ，我想从该 map 中提取每个键的最后一个值，但我无法获取:

import java.util.LinkedHashMap;
import java.util.Map;

class MyTestClass {

    private static final String almacenNombreClase = "Professor";

    private static final String TXT = "TXT";
    private static final String NUM = "NUM";

    public static void main(String[] args) {
        Map<String, Map<String, String>> mapNombreClaseYPropiedades = new LinkedHashMap<>();
        mapNombreClaseYPropiedades.put("Professor", Map.of("texto", TXT, 
                                                            "tipo", TXT, 
                                                            "prueba", NUM, 
                                                            "dificultad", NUM ));
        mapNombreClaseYPropiedades.put("Exam", Map.of("texto", TXT,
                                                      "nivel", NUM ));

        //values of mapNombreClaseYPropiedades
        Map<String, String> valores = mapNombreClaseYPropiedades.get(almacenNombreClase);

        valores.forEach((k, v) -> {
            // Here I want to check the last element of each entry
            if (v instanceof String ) {
                System.out.println("String " + k + ",");
            } else {
                System.out.println("Integer " + k + ",");
            }
        });
        // I want to see output
        "dificultad=NUM"
        "nivel=NUM"
    }
}

摘录:

dificultad=NUM
nivel=NUM

即每个键的最后 NUM 个条目

Answer 1

您可以使用 reduce从 Map<String,String> 中提取最后一个值然后使用 toMap 收集它们进入LinkedHashMap保存广告订单

但作为保留顺序的注释，您必须使用 LinkedHashMap也用于输入和输出

    Map<String,String> valores = mapNombreClaseYPropiedades.values()
            .stream()
            .map(map->map.entrySet().stream().reduce((prev,next)->next))
            .filter(Optional::isPresent)
            .map(Optional::get)
            .collect(Collectors.toMap(Map.Entry::getKey,Map.Entry::getValue, (prev,next)->next,LinkedHashMap::new));