如何在Java中返回经过过滤的Hashmap的值？

Question

因此，我创建了此Hashmap，并使用lambda和Stream对其进行了过滤

public class engineMain {

    public static void main(String[] args) {

        CarEngine engineOne = new CarEngine("A named Engine", 2000, 8, "E10");
        CarEngine engineTwo = new CarEngine("Another named Engine", 2200, 6, "E10");

        String a = "Another named Engine";

        HashMap<String, CarEngine> hmap = new HashMap();


        hmap.put(engineOne.getEngineName(), engineOne);
        hmap.put(engineTwo.getEngineName(), engineTwo);


        hmap.entrySet().stream().filter(e -> e.getValue().getEngineName().contains(a)).forEach(e -> System.out.println(e));



    }

}

如何改善我的最后一行代码，使其返回过滤后的值？现在它返回Another named Engine=javaapplication40.CarEngine@6ce253f1

我也尝试过这种方式

    HashMap<String, CarEngine> map = new HashMap<>();
  map.entrySet().stream().filter(x -> x.getKey().equals(a)).flatMap(x -> ((Map<String,CarEngine>) x.get(a)).values().stream() 
    .forEach(System.out::println);

谢谢

Answer 1

似乎您正在搜索：

CarEngine find = hmap.entrySet().stream()
        .filter(e -> e.getValue().getEngineName().contains(a))
        .map(Map.Entry::getValue)
        .findFirst()
        .orElse(null);