android - How to get the Context of an Application in a Fragment -

first have error message

caused by: java.lang.nullpointerexception: attempt invoke virtual method 'android.database.sqlite.sqlitedatabase android.content.context.openorcreatedatabase(java.lang.string, int, android.database.sqlite.sqlitedatabase$cursorfactory, android.database.databaseerrorhandler)' on null object reference                                                                               @ android.database.sqlite.sqliteopenhelper.getdatabaselocked(sqliteopenhelper.java:223)                                                                               @ android.database.sqlite.sqliteopenhelper.getwritabledatabase(sqliteopenhelper.java:163)                                                                               @ net.purplebug.mydoctorfinder.mydbhandler.showdoctors(mydbhandler.java:133)                                                                               @ net.purplebug.mydoctorfinder.homefragment.showdoctorlist(homefragment.java:131) 

so thought way wrote context parameter dbhandler instance.

this code triggers error. it's method in class extends fragment.

public void showdoctorlist() {     string result = "match found";      mydbhandler dbhandler = new mydbhandler(getcontext(), null, null, 1);      arraylist<arraylist<string>> docarray = new arraylist<arraylist<string>>();      doctordatamodel doctor = null;     try {         doctor = dbhandler.showdoctors();     } catch (sqlexception e) {         e.printstacktrace();     }      if (doctor != null) {          tablerow row = new tablerow(getactivity());         row.setlayoutparams(new layoutparams(layoutparams.match_parent, layoutparams.wrap_content));          docarray = doctor.getdocarray();          for(int = 0; < docarray.size(); i++) {             for(int j = 0; j < docarray.get(i).size(); j++) {                 textview textview = new textview(getactivity());                 textview.setlayoutparams(new layoutparams(layoutparams.wrap_content, layoutparams.wrap_content));                 textview.setpadding(5, 5, 5, 5);                 textview.settext(docarray.get(i).get(j) + " ");                  row.addview(textview);             }             tablelayout.addview(row);         }      } else {         result = "no match found";     }      log.d("query result", result);  } 

and code in dbhandler in relation error.

public mydbhandler(context context, string name, sqlitedatabase.cursorfactory factory, int version) {     super(context, database_name, factory, database_version);     this.mycontext = context; }  public doctordatamodel showdoctors() throws sqlexception {      int index = 0;     string doclastname, docfirstname, docid;      string query = "select doctor_id, lastname, firstname " + table_doctor;      sqlitedatabase db = this.getwritabledatabase();      cursor cursor = db.rawquery(query, null);      doctordatamodel doctor = new doctordatamodel();      while (cursor.movetonext()) {         docid = cursor.getstring(0);         doclastname = cursor.getstring(1);         docfirstname = cursor.getstring(2);         doctor.setdocarraylist(index, docid, doclastname, docfirstname);         index++;     }     index = 0;     cursor.close();     db.close();     return doctor; } 

i think it's way context in code.

mydbhandler dbhandler = new mydbhandler(getcontext(), null, null, 1);

or else problem. guys think?

you can define global variable:

private context context; 

and in oncreate method, initialize :

context = this.getactivity(); 

later use following avoid nullpointerexception:

if(context!=null){ //your code } 

and can use context variable in fragment functions/methods.