Attempt to invoke virtual method 'java.lang.String com.example.xxxxxxxx.models.User.getFullName()' on a null object reference

Question

first of all Happy new year to everyone. I am new to Android and Firebase and have a problem in passing data from one Activity (RegisterActivity) to another (MenuActivity) that contains the DrawerLayout. How can I fix my error? I've tried several solutions but none of them work. This is the error:

RegisterActivity.java

 @Override
            public void onComplete(@NonNull Task<AuthResult> task) {
                if(task.isSuccessful()) {
                    Toast.makeText(RegisterActivity.this, "User successful created", Toast.LENGTH_SHORT).show();
                    Intent registrationIntent = new Intent(getApplicationContext(), MenuActivity.class);
                    Bundle data = new Bundle();
                    data.putString("EMAIL", email);
                    registrationIntent.putExtras(data);
                    startActivity(registrationIntent);
                    finish();
                    progressDialog.dismiss();
                }
                else {
                    Toast.makeText(RegisterActivity.this, "Error! " +
                            task.getException().getMessage(), Toast.LENGTH_SHORT).show();
                }
            }

MenuActivity.java

private DrawerLayout drawer;
    private ImageView imageProfile;
    private TextView userName;
    private TextView email;
    private User user;
    private String identification;
    private NavigationView navigationView;

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

        Intent intentReceived = getIntent();
        Bundle data = intentReceived.getExtras();
        if(data != null){
            identification = data.getString("EMAIL");
        }
        else{
            identification = "";
        }

        View navHeaderView = ((NavigationView)findViewById(R.id.nav_view)).getHeaderView(0);

        ((TextView) navHeaderView.findViewById(R.id.userName)).setText(user.getUserName());
        ((TextView) navHeaderView.findViewById(R.id.userEmail)).setText(user.getEmail());

        Bitmap bitmapsinfoto = BitmapFactory.decodeResource(getResources(), R.drawable.profile);
        RoundedBitmapDrawable roundedBitmapDrawablesinfoto = RoundedBitmapDrawableFactory.create(getResources(), bitmapsinfoto);
        roundedBitmapDrawablesinfoto.setCircular(true);

        ((ImageView) navHeaderView.findViewById(R.id.imageProfile)).setImageDrawable(roundedBitmapDrawablesinfoto);

        if(user.getBytes()!=null) {
            byte[] foodImage = user.getBytes();
            Bitmap bitmap = BitmapFactory.decodeByteArray(foodImage, 0, foodImage.length);

            ((ImageView) navHeaderView.findViewById(R.id.imageProfile)).setImageBitmap(bitmap);

            Bitmap bitmap2 = ((BitmapDrawable)((ImageView) navHeaderView.findViewById(R.id.imageProfile)).getDrawable()).getBitmap();
            RoundedBitmapDrawable roundedBitmapDrawable = RoundedBitmapDrawableFactory.create(getResources(), bitmap2);
            roundedBitmapDrawable.setCircular(true);

            ((ImageView) navHeaderView.findViewById(R.id.imageProfile)).setImageDrawable(roundedBitmapDrawable);
        }

        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        drawer = findViewById(R.id.drawer_layout);
        NavigationView navigationView = findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar,
                R.string.navigation_drawer_open, R.string.navigation_drawer_close);

        drawer.addDrawerListener(toggle);
        toggle.syncState();

        if(savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
                    new MenuFragment()).commit();
            navigationView.setCheckedItem(R.id.nav_menu);
        }

User.java

public class User {

    private byte[] bytes;
    private String id, email, password, userName;
    private boolean active;

    public byte[] getBytes() {
        return bytes;
    }

    public void setBytes(byte[] bytes) {
        this.bytes = bytes;
    }

    public User() {  }

    public User(boolean active) {
        this.active = active;
    }

    public User(String id, String email, String password, String userName) {
        this.id = id;
        this.email = email;
        this.password = password;
        this.userName = userName;
    }

    public User(String id, String email, String password, byte[] bytes, String userName) {
        this.bytes = bytes;
        this.id = id;
        this.email = email;
        this.password = password;
        this.userName = userName;
    }

    public boolean isActive() {
        return active;
    }

    public void setActive(boolean active) {
        this.active = active;
    }

    public void setId(String id) {
        this.id = id;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public void setPassword(String pass) {
        this.password = pass;
    }

    public String getId() {
        return id;
    }

    public String getEmail() {
        return email;
    }

    public String getPassword() {
        return password;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }
}

Thanks in advance everyone for the answer.

Answer 1

From your code of MenuActivity.java it is somewhat clear that you haven't instantiated the object of User class. For ex,

((TextView) navHeaderView.findViewById(R.id.userName)).setText(user.getUserName());
((TextView) navHeaderView.findViewById(R.id.userEmail)).setText(user.getEmail());

In the above two lines you have used user.getUserName() but you haven't instantiated it before like User user=new User() or anything as you have overloaded the constructor.

Edit: Yours is not showing name and email in drawer because the user.getUserName() and user.getEmail() may be empty. Try passing the values in the constructor with all the required arguments.