private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListener;
public String email;
public String password;
private EditText emailedittext;
private EditText passwordedittext;
private TextView mStatusTextView;
private TextView mDetailTextView;
private static final String TAG = "EmailPassword";
SharedPreferences sharedpref;
private SharedPreferences.Editor loginStateEditor;
ProgressDialog progressdialog;
Handler handler = new Handler();
int status = 0;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    TwitterAuthConfig authConfig = new TwitterAuthConfig(TWITTER_KEY, TWITTER_SECRET);
    Fabric.with(this, new Twitter(authConfig));
    setContentView(R.layout.activity_main);

    EditText emailedittext = (EditText)findViewById(R.id.emailedittext);
    EditText passwordedittext = (EditText)findViewById(R.id.passwordedittext);
    final TextView mStatusTextView = (TextView) findViewById(R.id.mStatus);
    TextView mDetailTextView = (TextView) findViewById(R.id.mDetail);

    Button loginbutton = (Button)findViewById(R.id.login);
    Button signupbutton = (Button)findViewById(R.id.signup);
    Button signoutbutton = (Button)findViewById(R.id.signout);

    findViewById(R.id.login).setOnClickListener(this);
    findViewById(R.id.signup).setOnClickListener(this);
    findViewById(R.id.signout).setOnClickListener(this);

    CreateProgressDialog();



    sharedpref = getSharedPreferences("myPref", Context.MODE_PRIVATE);
    loginStateEditor = sharedpref.edit();

    if (sharedpref.getBoolean("success_login", false)) {
        // Start Your Menu Activity
        Intent i = new Intent(MainActivity.this, Menu.class);
        i.putExtra(EXTRA_MESSAGE, email);
        i.putExtra(EXTRA_MESSAGE, password);
        startActivity(i);

        mAuth = FirebaseAuth.getInstance();
        mAuthListener = new FirebaseAuth.AuthStateListener() {
            @Override
            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                FirebaseUser user = firebaseAuth.getCurrentUser();
                if (user != null) {
                    // User is signed in
                    Log.d(TAG, "onAuthStateChanged:signed_in:" + user.getUid());
                    Intent i = new Intent(MainActivity.this, Menu.class);
                    i.putExtra(EXTRA_MESSAGE, email);
                    i.putExtra(EXTRA_MESSAGE, password);
                    startActivity(i);
                } else {
                    // User is signed out
                    Log.d(TAG, "onAuthStateChanged:signed_out");
                }
                updateUI(user);
            }


        };}}

@SuppressLint("StringFormatInvalid")
private void updateUI(FirebaseUser user) {

    final TextView mStatusTextView = (TextView) findViewById(R.id.mStatus);
    TextView mDetailTextView = (TextView) findViewById(R.id.mDetail);

    Button loginbutton = (Button)findViewById(R.id.login);
    Button signupbutton = (Button)findViewById(R.id.signup);
    Button signoutbutton = (Button)findViewById(R.id.signout);

    findViewById(R.id.login).setOnClickListener(this);
    findViewById(R.id.signup).setOnClickListener(this);
    findViewById(R.id.signout).setOnClickListener(this);

    hideProgressDialog();{
    if (user != null) {
        mStatusTextView.setText(getString(R.string.emailpassword_status_fmt, user.getEmail()));
        mDetailTextView.setText(getString(R.string.firebase_status_fmt, user.getUid()));


        this.findViewById(R.id.login).setVisibility(View.GONE);
        this.findViewById(R.id.signup).setVisibility(View.GONE);
        this.findViewById(R.id.mStatus).setVisibility(View.GONE);
        this.findViewById(R.id.mDetail).setVisibility(View.GONE);
        this.findViewById(R.id.signout).setVisibility(View.VISIBLE);
    } else {
        mStatusTextView.setText(R.string.signed_out);
        mDetailTextView.setText(null);


        this.findViewById(R.id.login).setVisibility(View.VISIBLE);
        this.findViewById(R.id.signup).setVisibility(View.VISIBLE);
        this.findViewById(R.id.mStatus).setVisibility(View.GONE);
        this.findViewById(R.id.mDetail).setVisibility(View.GONE);
        this.findViewById(R.id.signout).setVisibility(View.GONE);
    }

    }

}





private void createAccount(final String email, final String password){
    Log.d(TAG, "createAccount:" + email);
    if (!validateForm()) {
        return;
    }

    showProgressDialog();

    mAuth.createUserWithEmailAndPassword(email, password)
            .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    Log.d(TAG, "createUserWithEmail:onComplete:" + task.isSuccessful());

                    // If sign in fails, display a message to the user. If sign in succeeds
                    // the auth state listener will be notified and logic to handle the
                    // signed in user can be handled in the listener.
                    if (!task.isSuccessful()) {
                        Toast.makeText(MainActivity.this, "Authentication failed.",
                                Toast.LENGTH_SHORT).show();
                        loginStateEditor.putBoolean("success_login", true);
                        loginStateEditor.commit();

                        Intent i = new Intent(MainActivity.this, Menu.class);
                        i.putExtra(EXTRA_MESSAGE, email);
                        i.putExtra(EXTRA_MESSAGE, password);
                        startActivity(i);
                    }
                    hideProgressDialog();


                    loginStateEditor.putBoolean("success_login", true);
                    loginStateEditor.commit();

                    Intent i = new Intent(MainActivity.this, Menu.class);
                    startActivity(i);
                }


            });
}

private void hideProgressDialog() {

    progressdialog.dismiss();

}


private boolean validateForm() {
    boolean valid = true;


    String email = emailedittext.getText().toString();
    if (TextUtils.isEmpty(email)) {
        emailedittext.setError("Required.");
        valid = false;
    } else {
        emailedittext.setError(null);
    }


    String password = passwordedittext.getText().toString();
    if (TextUtils.isEmpty(password)) {
        passwordedittext.setError("Required.");
        valid = false;
    } else {
        passwordedittext.setError(null);
    }
    return valid;
}

public void showProgressDialog() {
    status = 0;

    new Thread(new Runnable() {
        @Override
        public void run() {
            while(status < 100){

                status +=1;

                try{
                    Thread.sleep(200);
                }catch(InterruptedException e){
                    e.printStackTrace();
                }

                handler.post(new Runnable() {
                    @Override
                    public void run() {

                        progressdialog.setProgress(status);

                        if(status == 100){

                            progressdialog.dismiss();
                        }
                    }
                });
            }
        }
    }).start();

}







@Override
public void onClick(View v) {



    EditText emailedittext = (EditText)MainActivity.this.findViewById(R.id.emailedittext);
    EditText passwordedittext = (EditText)MainActivity.this.findViewById(R.id.passwordedittext);

    int i = v.getId();
    try {
        if (i == R.id.signup && emailedittext.getText() != null && passwordedittext.getText() != null) {

           createAccount(emailedittext.getText().toString(), passwordedittext.getText().toString());
            String email = emailedittext.getText().toString();
            String password = passwordedittext.getText().toString();


        } else if (i == R.id.login && emailedittext.getText() != null && passwordedittext.getText() != null) {

            signIn(emailedittext.getText().toString(), passwordedittext.getText().toString());
            String email = emailedittext.getText().toString();
            String password = passwordedittext.getText().toString();

        } else if (i == R.id.signout) {
            signOut();
        }
    }catch(Exception e){
        e.printStackTrace();
    }
}


public void CreateProgressDialog()
{

    progressdialog = new ProgressDialog(MainActivity.this);

    progressdialog.setIndeterminate(false);

    progressdialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);

    progressdialog.setCancelable(true);

    progressdialog.setMax(100);

    progressdialog.show();

}




private void signIn(final String email, final String password){
    Log.d(TAG, "signIn:" + email);
    if (!validateForm()) {
        return;
    }

    showProgressDialog();

    mAuth.signInWithEmailAndPassword(email, password)
            .addOnCompleteListener(MainActivity.this, new OnCompleteListener<com.google.firebase.auth.AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    Log.d(TAG, "signInWithEmail:onComplete:" + task.isSuccessful());

                    // If sign in fails, display a message to the user. If sign in succeeds
                    // the auth state listener will be notified and logic to handle the
                    // signed in user can be handled in the listener.
                    if (!task.isSuccessful()) {
                        onSuccess();
                        {
                            Log.w(TAG, "signInWithEmail", task.getException());
                            Toast.makeText(MainActivity.this, "Authentication failed.",
                                    Toast.LENGTH_SHORT).show();

                            loginStateEditor.putBoolean("success_login", true);
                            loginStateEditor.commit();
                            Intent i = new Intent(MainActivity.this, Menu.class);
                            i.putExtra(EXTRA_MESSAGE, email);
                            i.putExtra(EXTRA_MESSAGE, password);
                            startActivity(i);
                        }
                        if (!task.isSuccessful()) {
                            mStatusTextView.setText(R.string.auth_failed);
                        }
                        hideProgressDialog();

                    }


                }
            });

}


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

{
    if (user != null) {
        // Name, email address, and profile photo Url
        String name = user.getDisplayName();
        String email = user.getEmail();
        Uri photoUrl = user.getPhotoUrl();


        // The user's ID, unique to the Firebase project. Do NOT use this value to
        // authenticate with your backend server, if you have one. Use
        // FirebaseUser.getToken() instead.
        String uid = user.getUid();
    }

}






private void signOut() {
    mAuth.signOut();
    updateUI(null);
}

@Override
protected void onStart() {
    super.onStart();
}

@Override
protected void onStop() {
    super.onStop();
}

public void onSuccess(){
    sharedpref.getBoolean("success_login", true);
    loginStateEditor.commit();
    Intent i = new Intent(MainActivity.this, Menu.class);
    i.putExtra(EXTRA_MESSAGE, email);
    i.putExtra(EXTRA_MESSAGE, password);
    startActivity(i);
}

@Override
public void onClick(View v) {



    EditText emailedittext = (EditText)MainActivity.this.findViewById(R.id.emailedittext);
    EditText passwordedittext = (EditText)MainActivity.this.findViewById(R.id.passwordedittext);

    int i = v.getId();
    try {
        if (i == R.id.signup && emailedittext.getText() != null && passwordedittext.getText() != null) {

           createAccount(emailedittext.getText().toString(), passwordedittext.getText().toString());
            String email = emailedittext.getText().toString();
            String password = passwordedittext.getText().toString();


        } else if (i == R.id.login && emailedittext.getText() != null && passwordedittext.getText() != null) {

            signIn(emailedittext.getText().toString(), passwordedittext.getText().toString());
            String email = emailedittext.getText().toString();
            String password = passwordedittext.getText().toString();

        } else if (i == R.id.signout) {
            signOut();
        }
    }catch(Exception e){
        e.printStackTrace();
    }
}

ittouch W/System.err: java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference