Why is each element of Stream.of(ArrayList).foreach also ArrayList?

Thunfische :

@PostMapping("/countries")
public void createCountry(@Valid @RequestBody List<Country> countries) {

for(Country country: countries){
    countryRepository.save(country);
}

Stream.of(countries)
        .forEach(country -> countryRepository.save((Country)country));

}

I send this through postman

[
    {
        "name": "sweden",
        "cities": [
            {
                "name": "trelleborg"
            },
            {
                "name": "ystad"
            }
        ]
    },
        {
        "name": "japan",
        "cities": [
            {
                "name": "osaka"
            },
            {
                "name": "tokio"
            }
        ]
    }

]

With the for loop above the code works as intented, but with lambda expression below, I get this exception

java.lang.ClassCastException: java.util.ArrayList cannot be cast to com.qweqwe.Models.Country

What is the problem? Thanks

MyTwoCents :

Stream.of is used to build a Stream of Objects.

Since you are passing one object of type list, you get error here (Country)country

Either change Stream like this

Stream.of(countries.get(0), countries.get(1))
            .forEach(country -> countryRepository.save(country));

or

countries.stream().forEach(country -> countryRepository.save(country));

I tried below test data, adding just for Reference

List<UsersDTO> lstUser = new ArrayList<>();
UsersDTO userDto1 = new UsersDTO();
userDto1.setRecordsTotal(1);
userDto1.setRecordsFiltered(3);
UsersDTO userDto2 = new UsersDTO();
userDto2.setRecordsTotal(1);
userDto2.setRecordsFiltered(2);
lstUser.add(userDto1);
lstUser.add(userDto2);

Stream.of(lstUser.get(0), lstUser.get(1))
    .forEach(user -> System.out.println(user.getRecordsFiltered() ));

lstUser.stream().forEach(user -> System.out.println(user.getRecordsFiltered() ));

OUTPUT:
3
2
3
2