我有一个字符串列表,例如:
List<String> locations = Arrays.asList("US:5423","US:6321","CA:1326","AU:5631");
我想将其转换为 Map<String, List<String>>
,就像这样:
AU = [5631]
CA = [1326]
US = [5423, 6321]
我尝试了这段代码,并且它能够正常工作,但是在这种情况下,我必须创建一个新的类GeoLocation.java
。
List<String> locations=Arrays.asList("US:5423", "US:6321", "CA:1326", "AU:5631");
Map<String, List<String>> locationMap = locations
.stream()
.map(s -> new GeoLocation(s.split(":")[0], s.split(":")[1]))
.collect(
Collectors.groupingBy(GeoLocation::getCountry,
Collectors.mapping(GeoLocation::getLocation, Collectors.toList()))
);
locationMap.forEach((key, value) -> System.out.println(key + " = " + value));
GeoLocation.java
private class GeoLocation {
private String country;
private String location;
public GeoLocation(String country, String location) {
this.country = country;
this.location = location;
}
public String getCountry() {
return country;
}
public void setCountry(String country) {
this.country = country;
}
public String getLocation() {
return location;
}
public void setLocation(String location) {
this.location = location;
}
}
但我想知道,是否有办法将 List<String>
转换为 Map<String, List<String>>
而不引入新类。