[Solved] Android Java error:null pointer exception can’t see why?

Question

You have referenced in Your LoadingMain activity the following layout with setContentView:

   setContentView(R.layout.loading_main);

But this Layout does not have any button1. Instead, You are trying to reference a button from another layout, from activity_main.xml

   btnStartProgress = (Button) findViewById(R.id.button1);

This button1 is inside the activity_main.xml and You cannot reference a button in a layout that is not attached per setContentView. So What You have to do is, add a button to the loading_main.xml, BUT, don´t give it the same id like in the activity main “button1″. Sure, it works, to give same ids as long as the right layout is referenced, but id´s should be unique. If the button in the activity_layout should remain, give the id for your button inside loading_main.xml another name, maybe android:id=”@+id/loading_main_button_1”.

Accepted Answer

You have referenced in Your LoadingMain activity the following layout with setContentView:

   setContentView(R.layout.loading_main);

But this Layout does not have any button1. Instead, You are trying to reference a button from another layout, from activity_main.xml

   btnStartProgress = (Button) findViewById(R.id.button1);

This button1 is inside the activity_main.xml and You cannot reference a button in a layout that is not attached per setContentView. So What You have to do is, add a button to the loading_main.xml, BUT, don´t give it the same id like in the activity main “button1″. Sure, it works, to give same ids as long as the right layout is referenced, but id´s should be unique. If the button in the activity_layout should remain, give the id for your button inside loading_main.xml another name, maybe android:id=”@+id/loading_main_button_1”.