Firebase firestore throwing null object reference

Question

Logcat keeps throwing null object references while attempting to setup a document creation through firestore in an account creation process, code is below, im new to java with my university course so are unsure how to identify the problem.

Attempting to have information from the edittext fields stored into the firestore collection if the account is successfully created in auth, identified by the user ID of the created account.

public class CreateAccount extends AppCompatActivity implements 
View.OnClickListener {

private static final String TAG = "EmailPassword";
private EditText AccountEmail;
private EditText AccountPass;
private EditText AccountFirstname;
private EditText AccountSurname;
private EditText AccountTown;
private EditText AccountAge;
private FirebaseAuth mAuth;
public FirebaseFirestore cloudstorage;

@Override
//Code that executes when the activity begins; in this case simply setting the view.
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_create_account);
    AccountEmail = findViewById(R.id.textEditAccountEmail);
    AccountPass = findViewById(R.id.textEditAccountPass);
    AccountFirstname = findViewById(R.id.textEditAccountFirst);
    AccountSurname = findViewById(R.id.textEditAccountLast);
    AccountTown = findViewById(R.id.textEditAccountTown);
    AccountAge = findViewById(R.id.textEditAccountAge);
    mAuth = FirebaseAuth.getInstance();
    FirebaseFirestore cloudstorage = FirebaseFirestore.getInstance();
    //Auto signout for testing
    FirebaseAuth.getInstance().signOut();


}

public void createAccount(String email, String password) {
    Log.d(TAG, "createAccount:" + email);
    if (!Validate()) {
        return;
    }
    mAuth.createUserWithEmailAndPassword(email, password)
            .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    if (task.isSuccessful()) {
                        // Sign in success, update UI with the signed-in user's information
                        Log.d(TAG, "createUserWithEmail:success");

                        databasecreate();

                    } else {
                        // If sign in fails, display a message to the user.
                        Log.w(TAG, "createUserWithEmail:failure", task.getException());
                        Toast.makeText(CreateAccount.this, "Authentication failed.",
                                Toast.LENGTH_SHORT).show();
                    }

                }
            });
}

public boolean Validate() {
    boolean valid = true;
    String email = AccountEmail.getText().toString();
    if (TextUtils.isEmpty(email)) {
        AccountEmail.setError("Required.");
        valid = false;
    } else {
        AccountEmail.setError(null);
    }
    String password = AccountPass.getText().toString();
    if (TextUtils.isEmpty(password)) {
        AccountPass.setError("Required.");
        valid = false;
    } else {
        AccountPass.setError(null);
    }
    return valid;
}

public void databasecreate() {
    FirebaseUser user = mAuth.getCurrentUser();
    String uid = user.getUid();

    Map<String, Object> userlist = new HashMap<>();
    userlist.put("email", AccountEmail.getText());
    userlist.put("password", AccountPass.getText());
    userlist.put("Forename", AccountFirstname.getText());
    userlist.put("Surname", AccountSurname.getText());
    userlist.put("Town", AccountTown.getText());
    userlist.put("Age", AccountAge.getText());
    userlist.put("UserID", uid);

    cloudstorage.collection("users").document(uid)
            .set(userlist)
            .addOnSuccessListener(new OnSuccessListener<Void>() {
                @Override
                public void onSuccess(Void aVoid) {
                    Log.d(TAG, "Document successfully written!");
                }
            })
            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                    Log.w(TAG, "Error creating file", e);
                }
            });
}



@Override
public void onClick(View v) {
    int i = v.getId();
    if (i == R.id.btnCreate) {
        createAccount(AccountEmail.getText().toString(), AccountPass.getText().toString());
    }
}

public void onClickBack(View v) {
    Intent backIntent = new Intent(CreateAccount.this, Login.class);
    CreateAccount.this.startActivity(backIntent);
}
}

Error from log:

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.coffeedrive.myquote, PID: 20895
    java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.firebase.firestore.CollectionReference com.google.firebase.firestore.FirebaseFirestore.collection(java.lang.String)' on a null object reference
        at com.example.adam.myquote.CreateAccount.databasecreate(CreateAccount.java:137)
        at com.example.adam.myquote.CreateAccount$1.onComplete(CreateAccount.java:92)
        at com.google.android.gms.tasks.zzj.run(Unknown Source:4)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

Answer 1

In the function databasecreate() you're referencing the class variable cloudstorage . This variable is never initialized and is why you're getting an NPE . In your onCreate function you're initializing a different cloudstorage variable within the scope of the onCreate function. Simply change the line:

FirebaseFirestore cloudstorage = FirebaseFirestore.getInstance();

to

this.cloudstorage = FirebaseFirestore.getInstance();

or simply

cloudstorage = FirebaseFirestore.getInstance();

so that you initialize the class variable.