我是編程新手，我想添加一個設置菜單按鈕。如圖所示，我的應用程序不顯示三點按鈕。MainActivity.java :public class MainActivity extends AppCompatActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(this, getSupportFragmentManager());        ViewPager viewPager = findViewById(R.id.view_pager);        viewPager.setAdapter(sectionsPagerAdapter);        TabLayout tabs = findViewById(R.id.tabs);        tabs.setupWithViewPager(viewPager);    }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        getMenuInflater().inflate(R.menu.settings, menu);        return true;    }    @Override    public boolean onOptionsItemSelected(@NonNull MenuItem item) {        switch (item.getItemId()) {            case R.id.vueSatellite:                Toast.makeText(this, "Hi", Toast.LENGTH_SHORT).show();                return true;            default:                return super.onOptionsItemSelected(item);        }    }}