導航抽屜活動中的錯誤

Question

我正在嘗試爲Android創建導航抽屜。我按照這些頁面（this和this），但現在我卡住了。

這裏是我的代碼，基於地球的導航抽屜：

package com.example.side_navigation_from_scratch; 

import android.app.Activity; 
import android.app.Fragment; 
import android.app.FragmentManager; 
import android.app.SearchManager; 
import android.content.Intent; 
import android.content.res.Configuration; 
import android.os.Bundle; 

import android.support.v7.app.ActionBarDrawerToggle; 
import android.support.v4.widget.DrawerLayout; 

import android.view.LayoutInflater; 
import android.view.Menu; 
import android.view.MenuInflater; 
import android.view.MenuItem; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.AdapterView; 
import android.widget.ArrayAdapter; 
import android.widget.ListView; 
import android.widget.TextView; 
import android.widget.Toast; 


public class MainActivity extends Activity { 
    private DrawerLayout mDrawerLayout; 
    private ListView mDrawerList; 
    private ActionBarDrawerToggle mDrawerToggle; 
    private String mDrawerTitle; 
    private String mainTitle; 
    private String[] mPlanetTitles; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 

     setContentView(R.layout.activity_main); 
     super.onCreate(savedInstanceState); 
     //setContentView(R.layout.activity_main); 

     mainTitle = mDrawerTitle = (String) getTitle(); 

     mPlanetTitles = getResources().getStringArray(R.array.planets_array); 
     mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout); 
     mDrawerList = (ListView) findViewById(R.id.left_drawer); 

     // set up the drawer's list view with items and click listener 
     mDrawerList.setAdapter(new ArrayAdapter<String>(this, 
       R.layout.drawer_list_item, mPlanetTitles)); 
     mDrawerList.setOnItemClickListener(new DrawerItemClickListener()); 

     // ActionBarDrawerToggle ties together the the proper interactions 
     // between the sliding drawer and the action bar app icon 
     mDrawerToggle = new ActionBarDrawerToggle(
       this,     /* host Activity */ 
       mDrawerLayout,   /* DrawerLayout object */ 
       R.string.drawer_open, /* "open drawer" description for accessibility */ 
       R.string.drawer_close /* "close drawer" description for accessibility */ 
     ) { 
      public void onDrawerClosed(View view) { 
       super.onDrawerClosed(view); 
       getActionBar().setTitle(mainTitle); 
       invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu() 
      } 

      public void onDrawerOpened(View drawerView) { 
       super.onDrawerOpened(drawerView); 
       getActionBar().setTitle(mDrawerTitle); 
       invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu() 
      } 
     }; 

     mDrawerLayout.setDrawerListener(mDrawerToggle); 

     if (savedInstanceState == null) { 
      selectItem(0); 
     } 

     // enable ActionBar app icon to behave as action to toggle nav drawer 
     getActionBar().setDisplayHomeAsUpEnabled(true); 
     getActionBar().setHomeButtonEnabled(true); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     MenuInflater inflater = getMenuInflater(); 
     inflater.inflate(R.menu.menu_main, menu); 
     return super.onCreateOptionsMenu(menu); 
    } 

    /* Called whenever we call invalidateOptionsMenu() */ 
    @Override 
    public boolean onPrepareOptionsMenu(Menu menu) { 
     // If the nav drawer is open, hide action items related to the content view 
     boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList); 
     menu.findItem(R.id.action_websearch).setVisible(!drawerOpen); 
     return super.onPrepareOptionsMenu(menu); 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     // The action bar home/up action should open or close the drawer. 
     // ActionBarDrawerToggle will take care of this. 
     if (mDrawerToggle.onOptionsItemSelected(item)) { 
      return true; 
     } 
     // Handle action buttons 
     switch(item.getItemId()) { 
      case R.id.action_websearch: 
       // create intent to perform web search for this planet 
       Intent intent = new Intent(Intent.ACTION_WEB_SEARCH); 
       intent.putExtra(SearchManager.QUERY, getActionBar().getTitle()); 
       // catch event that there's no activity to handle intent 
       if (intent.resolveActivity(getPackageManager()) != null) { 
        startActivity(intent); 
       } else { 
        Toast.makeText(this, R.string.app_not_available, Toast.LENGTH_LONG).show(); 
       } 
       return true; 
      default: 
       return super.onOptionsItemSelected(item); 
     } 
    } 

    /* The click listner for ListView in the navigation drawer */ 
    private class DrawerItemClickListener implements ListView.OnItemClickListener { 
     @Override 
     public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
      selectItem(position); 
     } 
    } 

    private void selectItem(int position) { 
     // update the main content by replacing fragments 
     Fragment fragment = new PlanetFragment(); 
     Bundle args = new Bundle(); 
     args.putInt(PlanetFragment.ARG_PLANET_NUMBER, position); 
     fragment.setArguments(args); 

     FragmentManager fragmentManager = getFragmentManager(); 
     fragmentManager.beginTransaction().replace(R.id.content_frame, fragment).commit(); 

     // update selected item and title, then close the drawer 
     mDrawerList.setItemChecked(position, true); 
     setTitle(mPlanetTitles[position]); 
     mDrawerLayout.closeDrawer(mDrawerList); 
    } 

    @Override 
    public void setTitle(CharSequence title) { 
     mainTitle = (String) title; 
     getActionBar().setTitle(mainTitle); 
    } 

    /** 
    * When using the ActionBarDrawerToggle, you must call it during 
    * onPostCreate() and onConfigurationChanged()... 
    */ 

    @Override 
    protected void onPostCreate(Bundle savedInstanceState) { 
     super.onPostCreate(savedInstanceState); 
     // Sync the toggle state after onRestoreInstanceState has occurred. 
     mDrawerToggle.syncState(); 
    } 

    @Override 
    public void onConfigurationChanged(Configuration newConfig) { 
     super.onConfigurationChanged(newConfig); 
     // Pass any configuration change to the drawer toggls 
     mDrawerToggle.onConfigurationChanged(newConfig); 
    } 

    /** 
    * Fragment that appears in the "content_frame", shows a planet 
    */ 
    public static class PlanetFragment extends Fragment { 
     public static final String ARG_PLANET_NUMBER = "planet_number"; 

     public PlanetFragment() { 
      // Empty constructor required for fragment subclasses 
     } 

     @Override 
     public View onCreateView(LayoutInflater inflater, ViewGroup container, 
           Bundle savedInstanceState) { 
      View rootView = inflater.inflate(R.layout.fragment_planet, container, false); 
      int i = getArguments().getInt(ARG_PLANET_NUMBER); 
      String planet = getResources().getStringArray(R.array.planets_array)[i]; 
      TextView planetName = (TextView) rootView.findViewById(R.id.text); 

      getActivity().setTitle(planet); 
      return rootView; 
     } 
    } 
} 

我得到這取決於我的變化做出不同的錯誤。 就像它是現在，我得到

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setTitle(java.lang.CharSequence)' on a null object reference 

ActionBarActivity已被棄用，所以我不打算使用它，但如果我改變活動以AppCompatActivity，我得到

java.lang.IllegalArgumentException: AppCompat does not support the current theme features 

我在做什麼錯？哪個更好用：Activity，ActionBarActivity或AppCompatActivity？在此先感謝

Answer 1

感謝Raghunandan我設法解決這個問題：我更改了Activity到AppCompatActivity並替換getActionBar getSupportActionBar。我沒有更多的NPE