spinner.setAdapter（adapter）上的NullPointerException

Question

我对编程还很陌生，所以请原谅我遇到这个简单的问题。我的问题是尝试运行此代码时遇到NullPointerException，因为我无法在微调器上调用setAdapter方法。（微调器似乎为空，因此：c）感谢您提出解决此问题的所有建议：）

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Toolbar toolbar=findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        drawer=findViewById(R.id.draw_layout);
        NavigationView navigationView=findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

        ActionBarDrawerToggle toggle= new ActionBarDrawerToggle(this, drawer, toolbar,R.string.navigation_drawer_open,R.string.navigation_drawer_close);

        drawer.addDrawerListener(toggle);
        toggle.syncState();
        if (savedInstanceState==null){
        getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,new TrackingPlanFragment()).commit();
        navigationView.setCheckedItem(R.id.nav_home);}

        textInputExercise=findViewById(R.id.text_input_exercise);
        textInputWeight=findViewById(R.id.text_input_weight);
        textInputSets=findViewById(R.id.text_input_sets);
        textInputReps=findViewById(R.id.text_input_reps);

        Spinner spinner=(Spinner) findViewById(R.id.spinner1);
        ArrayAdapter<CharSequence> adapter=ArrayAdapter.createFromResource(this,R.array.numbers,android.R.layout.simple_spinner_item);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(adapter);
    }

 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Spinner.setAdapter(android.widget.SpinnerAdapter)' on a null object reference
        at com.example.fitenss_tracking_app.MainActivity.onCreate(MainActivity.java:61)

Answer 1