TextView.setText() Null Pointer Exception

Question

I'm currently facing a problem when trying to edit the text of a TextView in the OnCreate method of an Activity. As I understand, setContentView must be called before trying to change the text, however I am still having trouble with this.

Here is the code in question :

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

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.addDrawerListener(toggle);
    toggle.syncState();

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

    userEmailtext = (TextView) findViewById(R.id.emailText);
    mAuth = FirebaseAuth.getInstance();
    mUser = mAuth.getCurrentUser();
    userEmailtext.setText("This Does Not Work");
}

This Activity includes the Android Studio default sliding menu. The aim of this setText is to change the email address text of the sliding menu. I believe the problem may lie in the fact that the sliding menu is part of a different layout file, meaning there is no "emailText" textview leading to the null pointer exception, however I am still not sure how this would be rectified.

Any help is appreciated.

score 0 · Answer 1 · answered Apr 04 '18 at 11:31

0

It depends on where is your R.id.emailText component.

If it is directly in your R.layout.activity_dash_board, the code should work. If it is in R.id.nav_view, you should reach it via navigationView.findViewById(R.id.emailText)

answered Apr 04 '18 at 11:31

ibrahimyilmaz

18,331
13
61
80

score 0 · Accepted Answer · answered Apr 04 '18 at 11:31

0

You should init your TextView instace from NavigationView. In your case:

userEmailtext = (TextView) navigationView.getHeaderView(0).findViewById(R.id.emailText);

answered Apr 04 '18 at 11:31

Jose Angel Maneiro

1,226
9
20

Thanks for the solution, works perfectly! Would you please explain the use of the number 0 in the getHeaderView method, does it act as some sort of index? – Sam Apr 04 '18 at 14:02
Yeah, you can read this answer to complete the information. Greetings. https://stackoverflow.com/a/33194816/4871526 – Jose Angel Maneiro Apr 04 '18 at 14:19

TextView.setText() Null Pointer Exception

2 Answers2