java - Android app force close when executed -


execution of following code crashed. there no error messages.

it should open web.java upon button press , creates key-value.

mainactivity.java

import android.app.activity; import android.content.intent; import android.content.sharedpreferences; import android.os.bundle; import android.preference.preferencemanager; import android.view.view; import android.view.view.onclicklistener; import android.widget.button; import android.widget.spinner;  public class mainactivity extends activity {      private button btngo;     final spinner page = (spinner)findviewbyid(r.id.txtpage);     string pagechoice;      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);         final sharedpreferences sharedpref =preferencemanager.getdefaultsharedpreferences(this);         btngo = (button)findviewbyid(r.id.btngo);         btngo.setonclicklistener(new onclicklistener() {              @override             public void onclick(view v) {                 pagechoice = page.getselecteditem().tostring();                  //hopefully allow "global" url setting.                 sharedpreferences.editor editor = sharedpref.edit();                 editor.putstring("key1", pagechoice);                 editor.commit();                 startactivity(new intent(mainactivity.this, web.class));             }         });     } }

this not suppose in class variables:

final spinner page = (spinner)findviewbyid(r.id.txtpage);

this need inside oncreate()method. after setcontentview(), method variable.

findviewbyid() use context lookup view, , need have context (and layout resource need inflated). context in oncreate execution, not when class loaded.


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