NullPointerException with android.support.v7.widget.Toolbar

Question

I am currently trying to implement a navigation drawer in my app. I am having an issue with the Toolbar being null. I have done many searches online and tried many different

Answer 1

check both line call is ok or not

    setContentView(R.layout.layout_file)
    toolbar = (Toolbar) findViewById(R.id.toolbar_top)