java - 将复选框添加到抽屉导航 ListView 时出错

Question

我正在尝试向我的 Android 应用程序添加自定义抽屉导航。我需要的是添加一个包含图标、名称和复选框的 ListView 。

目前，我可以添加图标和名称。

这是我在 NavigationDrawerFragment.java

中的 onCreateView

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        mDrawerListView = (ListView) inflater.inflate(
                R.layout.fragment_navigation_drawer, container, false);
        mDrawerListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                selectItem(position);
            }
        });

        final TypedArray typedArray = getResources().obtainTypedArray(R.array.sections_icons);
        mDrawerListView.setAdapter(new ArrayAdapter<String>(
                getActionBar().getThemedContext(),
                android.R.layout.simple_list_item_activated_1,
                android.R.id.text1,
                getResources().getStringArray(R.array.sections)
        ) {
            @Override
            public View getView(int position, View convertView, ViewGroup parent) {
                View v = super.getView(position, convertView, parent);
                int resourceId = typedArray.getResourceId(position, 0);
                Drawable drawable = getResources().getDrawable(resourceId);
                ((TextView) v).setCompoundDrawablesWithIntrinsicBounds(drawable, null, null, null);
                return v;
            }
        });

        mDrawerListView.setItemChecked(mCurrentSelectedPosition, true);
        return mDrawerListView;
    }

但是，我无法将复选框添加到我的抽屉导航中。 于是，我关注了this我尝试通过添加 mDrawerList.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);

来添加复选框

这给了我以下错误。

05-05 11:24:49.537    3640-3640/com.myayubo E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.myayubo, PID: 3640
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myayubo/com.myayubo.MainActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2338)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
            at android.app.ActivityThread.access$800(ActivityThread.java:151)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321)
            at android.os.Handler.dispatchMessage(Handler.java:110)
            at android.os.Looper.loop(Looper.java:193)
            at android.app.ActivityThread.main(ActivityThread.java:5299)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:829)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:645)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.myayubo.MainActivity.onCreate(MainActivity.java:67)
            at android.app.Activity.performCreate(Activity.java:5264)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2302)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
            at android.app.ActivityThread.access$800(ActivityThread.java:151)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321)
            at android.os.Handler.dispatchMessage(Handler.java:110)
            at android.os.Looper.loop(Looper.java:193)
            at android.app.ActivityThread.main(ActivityThread.java:5299)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:829)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:645)
            at dalvik.system.NativeStart.main(Native Method)

有人请告诉我如何在我的代码中添加复选框。

提前致谢。 :)

Answer 1

你应该这样做:

@Override
 public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
   View rootView = inflater.inflate(R.layout.fragment_navigation_drawer, container, false);

   ListView mDrawerListView = (ListView) rootView.findViewById(R.id.listView);
   mDrawerList.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
    // Other stuff
   return rootView; 
 }

编辑 1:

public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
         View rootView = inflater.inflate(R.layout.fragment_navigation_drawer, container, false);

   ListView mDrawerListView = (ListView) rootView.findViewById(R.id.listView);
   mDrawerList.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);

        mDrawerListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                selectItem(position);
            }
        });

        final TypedArray typedArray = getResources().obtainTypedArray(R.array.sections_icons);
        mDrawerListView.setAdapter(new ArrayAdapter<String>(
                getActionBar().getThemedContext(),
                android.R.layout.simple_list_item_activated_1,
                android.R.id.text1,
                getResources().getStringArray(R.array.sections)
        ) {
            @Override
            public View getView(int position, View convertView, ViewGroup parent) {
                View v = super.getView(position, convertView, parent);
                int resourceId = typedArray.getResourceId(position, 0);
                Drawable drawable = getResources().getDrawable(resourceId);
                ((TextView) v).setCompoundDrawablesWithIntrinsicBounds(drawable, null, null, null);
                return v;
            }
        });

        mDrawerListView.setItemChecked(mCurrentSelectedPosition, true);
        return rootView;
    }

您对 ListView 的绑定(bind)做错了。

希望这有意义。