Firebase 用户注册/用户名身份验证

Question

Im very new new to Firebase and Im creating my first app.

Im having 2 issues that I would like to get some help please.

I have linked my Android Studio application to my Firebase project and created the code for the Sigup of new user.

SignupActivity.java

    package com.company.fbaseapp.activities;

    import android.content.Intent;
    import android.support.annotation.NonNull;
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.util.Log;
    import android.view.View;
    import android.view.WindowManager;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.ProgressBar;
    import android.widget.Toast;

    import com.google.android.gms.tasks.OnCompleteListener;
    import com.google.android.gms.tasks.Task;
    import com.google.firebase.auth.AuthResult;
    import com.google.firebase.auth.FirebaseAuth;
    import com.company.fbaseapp.R;

    public class SignupActivity extends AppCompatActivity {

        private static final String TAG = "SignupActivity";

        private EditText mUsername;
        private EditText mEmail;
        private EditText mPassword;

        private Button mSignup;

        private ProgressBar mProgressBar;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_signup);

            //mUsername = (EditText) findViewById(R.id.input_username);

            mEmail = (EditText) findViewById(R.id.input_email);
            mPassword = (EditText) findViewById(R.id.input_password);
            mSignup = (Button) findViewById(R.id.btn_signup);

            mSignup.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View view) {

                    Log.d(TAG, "onClick: attempting to signup.");

                    // Check for null valued EditText fields
                    if (!isEmpty (mEmail.getText().toString()) && !isEmpty (mPassword.getText().toString())) {

                        signupNewUser(mEmail.getText().toString(), mPassword.getText().toString());

                        //Toast.makeText(SignupActivity.this, "Thank you for signing up", Toast.LENGTH_SHORT).show();
                    }
                    else {
                        Toast.makeText(SignupActivity.this, "You must fill out all the fields", Toast.LENGTH_SHORT).show();
                    }

                }

            } );

            hideSoftKeyboard();

        }

        private void signupNewUser(String email, String password) {

            showDialog();

            FirebaseAuth.getInstance().createUserWithEmailAndPassword(email, password)
                    .addOnCompleteListener( new OnCompleteListener<AuthResult>() {

                        @Override
                        public void onComplete(@NonNull Task<AuthResult> task) {

                            Log.d(TAG, "onComplete: onComplete: " + task.isSuccessful());

                            if (task.isSuccessful()) {

                                Log.d(TAG, "onComplete: AuthState: " + FirebaseAuth.getInstance()
                                        .getCurrentUser()
                                        .getUid());

FirebaseUser currentperson=FirebaseAuth.getInstance().getCurrentUser();
                            DatabaseReference ref=FirebaseDatabase.getInstance().getReference().child("Users").child(currentperson.getUid());
                            ref.child("Username").setValue(name);

                                FirebaseAuth.getInstance().signOut();

                                redirectLoginScreen();

                            }
                            if (!task.isSuccessful()) {

                                Toast.makeText(SignupActivity.this, "Unable to signup", Toast.LENGTH_SHORT).show();

                            }

                        }

                    });

        }

        /**
         * Return true if the @param is null
         * @param string
         * @return
         */
        private boolean isEmpty(String string){
            return string.equals("");
        }

        /**
         * Redirects the user to the login screen
         */
        private void redirectLoginScreen(){
            Log.d(TAG, "redirectLoginScreen: redirecting to login screen.");

            Intent intent = new Intent(SignupActivity.this, LoginActivity.class);
            startActivity(intent);
            finish();
        }

        private void showDialog(){
            mProgressBar.setVisibility(View.VISIBLE);

        }

        private void hideDialog(){
            if(mProgressBar.getVisibility() == View.VISIBLE){
                mProgressBar.setVisibility(View.INVISIBLE);
            }
        }

        private void hideSoftKeyboard(){
            this.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);
        }

    }

LogCat

12-30 01:19:18.492 31917-31917/com.company.fbaseapp D/SignupActivity: onClick: attempting to signup.
12-30 01:19:18.493 31917-31917/com.company.fbaseapp D/AndroidRuntime: Shutting down VM
12-30 01:19:18.497 31917-31917/com.company.fbaseapp E/AndroidRuntime: FATAL EXCEPTION: main

Process: com.company.fbaseapp, PID: 31917
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ProgressBar.setVisibility(int)' on a null object reference
at com.company.fbaseapp.activities.SignupActivity.showDialog(SignupActivity.java:126)
at com.company.fbaseapp.activities.SignupActivity.signupNewUser(SignupActivity.java:72)
at com.company.fbaseapp.activities.SignupActivity.access$300(SignupActivity.java:21)
at com.company.fbaseapp.activities.SignupActivity$1.onClick(SignupActivity.java:54)
at android.view.View.performClick(View.java:6289)
at android.view.View$PerformClick.run(View.java:24800)
at android.os.Handler.handleCallback(Handler.java:789)
at android.os.Handler.dispatchMessage(Handler.java:98)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6809)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
12-30 01:19:18.499 31917-31917/com.company.fbaseapp D/AppTracker: App Event: crash

The first issue is that the application is crashing when I click on the mSignup button.

Thesecond issue is that I would like to know how I can add a Unique Username to each registerd user.

Please help me figure out how to fix these 2 issues.

Thanks

Answer 1

This is the error:

`Attempt to invoke virtual method 'void android.widget.ProgressBar.setVisibility(int)' on a null object reference`

the progressbar is null, you need to add this:

mProgressBar = (ProgressBar) findViewById(R.id.progressBar); //your id in xml

Regarding unique username for each user, you can do this:

 FirebaseUser currentperson=FirebaseAuth.getInstance().getCurrentUser();

then if you are saving to the database, you can do this:

      DatabaseReference ref=FirebaseDatabase.getInstance().getReference().child("Users");
   ref.child(currentperson.getUid());

The above will add a unique userid to each username.

If you mean to add a unique username in authentication, you cannot do that. But the email is unique there by default so if you try to register another user with same email then you will get error:authentication failed

Edit:

You cannot add username in authentication, if you go to the console then you will see the userid and email there added. The authentication provides you with a userid but username cannot be added in the authentication, it can only be added in the database, can do this:

     DatabaseReference ref=FirebaseDatabase.getInstance().getReference().child("Users").child(currentperson.getUid());
   ref.child("Username").setValue(name);

then in your firebase database you would have this:

    Users
         LA0rRvP4TrewYbMSl0bDA3ork8h2
                    Username: hisname_here