Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference
An Activity
is not fully initialized and ready to look up views until after setContentView(...)
is called in onCreate()
.
Only declare the fields like the following:
private EditText usernameField, passwordField;private TextView error;private ProgressBar progress;
and then assign the values in onCreate
:
@Overrideprotected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_login); usernameField = (EditText)findViewById(R.id.username); passwordField = (EditText)findViewById(R.id.password); error = (TextView)findViewById(R.id.error); progress = (ProgressBar)findViewById(R.id.progress);}
Might not be part of the problem but as an extra bit of advice a Timer
runs the TimerTask
on a background thread and that should be avoided in this case. Replace the Timer
with a Handler
instead to run it on the UI thread.
new Handler().postDelayed(new Runnable() { @Override public void run() { Intent intent = new Intent(SplashActivity.this, LoginActivity.class); startActivity(intent); finish(); }}, 1500);
Views defined in xml file can only be accessed in java code, after setting the ContentView
as the required xml file using:
setContentView(R.layout.xml_file_name);
So 1st call above method inside onCreate
method and then initialize the View
instances inside onCreate
or inside the methods in which the instance will be used.