Java: a null pointer exception after a null-check

Question

Would anyone be so kind as to help me to understand how can I get a null pointer exception here?

    @Override
    public Collection<? extends GrantedAuthority> getAuthorities() {
        Collection<GrantedAuthority> grantedAuthorityCollection = new ArrayList<>();
        Collection<UserRole> userRoleCollection = user.getUserRoleList();
        if(userRoleCollection != null) {
            if (userDetailsService.getAuthorities(userRoleCollection) != null) {
            // ^^^ it occurs at the line above ^^^
                grantedAuthorityCollection.addAll(userDetailsService.getAuthorities(userRoleCollection));
            }
        }
        return grantedAuthorityCollection;
    }

Here's what I get at run-time:

java.lang.NullPointerException: null
    at ua.tucha.passpass.web.security.UserDetails.getAuthorities(UserDetails.java:31)
    at org.springframework.security.authentication.dao.AbstractUserDetailsAuthenticationProvider.createSuccessAuthentication(AbstractUserDetailsAuthenticationProvider.java:225)
    at org.springframework.security.authentication.dao.DaoAuthenticationProvider.createSuccessAuthentication(DaoAuthenticationProvider.java:137)
    at org.springframework.security.authentication.dao.AbstractUserDetailsAuthenticationProvider.authenticate(AbstractUserDetailsAuthenticationProvider.java:197)
    ...

How can it be? I've just made sure if there's not null in userRoleCollection, the next instruction wouldn't have been executed if there was null, would it?

Thank you very much in advance for your kind help.

Damn! Thank you, it really was `null`, I forgot to make it static! — Volodymyr Melnyk, Mar 20 '19 at 16:08

Java: a null pointer exception after a null-check

0 Answers0