Android-如何将FirebaseUid保存到SharedPreferences？

试试这样:

private SharedPreferences sharedPref;
FirebaseAuth auth = FirebaseAuth.getInstance();
FirebaseAuth.AuthStateListener authListener = new FirebaseAuth.AuthStateListener() {
    @Override
    public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
        FirebaseUser firebaseUser = firebaseAuth.getCurrentUser();
        if (firebaseUser != null) {
            String userId = firebaseUser.getUid();
            String userEmail = firebaseUser.getEmail();
            sharedPref = getPreferences(MODE_PRIVATE);
            SharedPreferences.Editor editor = sharedPref.edit();
            editor.putString("firebasekey", userId);
            editor.commit();
        } 
    }
};

要在其他活动中检索:

        sharedPref = getPreferences(MODE_PRIVATE);
        String UserId = sharedPref.getString("firebasekey", "");