Null pointer Exception on setOnClickListener

Question

I am having an issue with a click listener for a login modal submit button   This is the error   Caused by  java lang NullPointerException  Attempt to invoke virtual method  void android widget Button setOnClickListener android view View OnClickListener   on a null object reference   I have a reasonable understanding of what a null pointer exception is and I have search thoroughly for an issue similar to mine  I have tried to reformat the click listener in several ways  made sure I have the correct view ID etc   package    import    public class MainActivity extends ActionBarActivity implements     NavigationDrawerFragment NavigationDrawerCallbacks          Variables     String currentPage           Stack lt String gt  crumbs   new Stack lt String gt           Fragment managing the behaviors  interactions and presentation of the navigation drawer      private NavigationDrawerFragment mNavigationDrawerFragment         Used to store the last screen title  For use in   link  restoreActionBar         public CharSequence mTitle        temp     AuthenticateUserTokenResult authenticateUserTokenResult      String loginErrorMessage           String loginErrorTitle           Boolean logonSuccessful   false      Dialog loginDialog          Login EditTexts     EditText Username      EditText CompanyID      EditText Password      Button Submit        Override     protected void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout activity main            mNavigationDrawerFragment    NavigationDrawerFragment  getSupportFragmentManager   findFragmentById R id navigation drawer           mTitle   getTitle        Set up the drawer          mNavigationDrawerFragment setUp R id navigation drawer   DrawerLayout  findViewById R id drawer layout             if authenticateUserTokenResult    null                attemptLogin                         public void attemptLogin             loginDialog   new Dialog this android R style Theme Translucent NoTitleBar           loginDialog requestWindowFeature Window FEATURE NO TITLE           loginDialog setContentView R layout login modal           loginDialog setCancelable false             loginDialog setOnCancelListener cancelListener           loginDialog show            Submit    Button findViewById R id Submit           Submit setOnClickListener new View OnClickListener      the error is on this line  specifically the  setOnClickListener                         Override             public void onClick View v                                ClyxUserLogin user   new ClyxUserLogin                    Username    EditText findViewById R id Username                   user logon   Username getText   toString                    CompanyID    EditText findViewById R id CompanyID                   user idCompany   Integer parseInt CompanyID getText   toString                     Password    EditText findViewById R id Password                   user password   Password getText   toString                    user idApplication   142                  authenticate user                                     There is more  obviously  but not relevant to the topic I think  Here is the XML file for the dialog that has the button on it    lt RelativeLayout xmlns android  http   schemas android com apk res android      android orientation  vertical      android layout width  fill parent      android layout height  fill parent      android background   3366FF  gt        lt RelativeLayout         android layout width  wrap content          android layout height  wrap content          android layout centerInParent  true          android background   FFFFFF   gt            lt TextView             android id    id LoginTitle              android layout width  200dp              android layout height  wrap content              android gravity  center horizontal              android layout marginTop  10dp              android layout marginStart  10dp              android textColor   000000              android textSize  20sp              android text  Login    gt            lt EditText             android id    id Username              android layout width  200dp              android layout height  wrap content              android layout below    id LoginTitle              android layout margin  10dp              android hint  Username    gt            lt EditText             android id    id CompanyID              android layout width  200dp              android layout height  wrap content              android layout below    id Username              android layout alignStart    id Username              android inputType  number              android hint  Company ID    gt            lt EditText             android id    id Password              android layout width  200dp              android layout height  wrap content              android layout below    id CompanyID              android layout alignStart    id Username              android layout marginTop  10dp              android layout marginBottom  10dp              android inputType  textPassword              android hint  Password    gt            lt Button             android id    id Submit              android layout width  wrap content              android layout height  wrap content              android layout below    id Password              android layout marginBottom  10dp              android layout centerHorizontal  true              android text  Login    gt        lt  RelativeLayout gt    lt  RelativeLayout gt    Any help would be greatly appreciated

User · Accepted Answer

Submit is null because it is not part of activity main xml  When you call findViewById inside an Activity  it is going to look for a View inside your Activity s layout   try this instead    Submit    Button loginDialog findViewById R id Submit     Another thing   you use   android layout below    id LoginTitle    but what you want is probably   android layout below   id LoginTitle    See this question about the difference between  id and   id

User · Answer

Try giving your Button in your main xml a more descriptive name such as    lt Button                 android id    id buttonXYZ     use lowercase in your xml files  at least  the first letter   And then in your MainActivity class  declare it as   Button buttonXYZ   In your onCreate Bundle savedInstanceState  method  define it as   buttonXYZ    Button  findViewById R id buttonXYZ     Also  move the Buttons TextViews outside and place them before the  setOnClickListener - it makes the code cleaner   Username    EditText findViewById R id Username   CompanyID    EditText findViewById R id CompanyID

User · Answer

android widget Button setOnClickListener android view View OnClickListener     on a null object reference   Because Submit button is inside login modal so you need to use loginDialog view to access button   Submit    Button loginDialog findViewById R id Submit

User · Answer

I too got similar error when i misplaced the code  text  TextView findViewById R id text     this line has to be below setcontentview setContentView R layout activity my otype     this is the correct place text setOnClickListener new View OnClickListener              Override         public void onClick View view                            I got it working on placing the code in right order as shown below  setContentView R layout activity my otype   text  TextView findViewById R id text    text setOnClickListener new View OnClickListener              Override         public void onClick View view

[java] Null pointer Exception on .setOnClickListener

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