本人的MainActivity的代码如下：
public class MainActivity extends AppCompatActivity {
private ViewPager mViewPage;
private MainPagerAdapter mPagerAdapter;
private ChatPageFragment mChatPage = new ChatPageFragment();
private MusicGroundFragment mMusicGround = new MusicGroundFragment();
private ContactPageFragment mContactPage = new ContactPageFragment();
private RecyclerView mChatRecycleView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//一些无关代码
initView();
}
private void initView(){
mViewPage = (ViewPager) findViewById(R.id.main_view_pager);
//mChatRecycleView = (RecyclerView) findViewById(R.id.chat_list_view);
FragmentTransaction ft= getSupportFragmentManager().beginTransaction();
ft.add(R.id.main_view_pager,mChatPage);
ft.add(R.id.main_view_pager,mMusicGround);
ft.add(R.id.main_view_pager,mContactPage);
ft.commit();
mChatRecycleView = mChatPage.getRecycleView();
mChatRecycleView.setLayoutManager(new LinearLayoutManager(this));
mChatRecycleView.setAdapter(new ChatPageAdapter(this));
ArrayList<Fragment> fragments = new ArrayList<>();
fragments.add(mChatPage);
fragments.add(mMusicGround);
fragments.add(mContactPage);
mPagerAdapter = new MainPagerAdapter(fragments);
mViewPage.setAdapter(mPagerAdapter);
}
//一些自动生成的代码
}
本人的activity_main的代码如下：
<?xml version="1.0" encoding="utf-8"?> <android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:fitsSystemWindows="true" tools:context="com.f1993xuboss.musicpark.MainActivity"> <android.support.design.widget.AppBarLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:theme="@style/AppTheme.AppBarOverlay"> <android.support.v7.widget.Toolbar android:id="@+id/toolbar" android:layout_width="match_parent" android:layout_height="?attr/actionBarSize" android:background="?attr/colorPrimary" app:popupTheme="@style/AppTheme.PopupOverlay" /> </android.support.design.widget.AppBarLayout> <android.support.v4.view.ViewPager android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/main_view_pager"> <android.support.v4.view.PagerTitleStrip android:id="@+id/pager_title_strip" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_gravity="bottom" > <ImageSwitcher android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/chat_title_view" android:layout_marginLeft="0dp"/> <ImageSwitcher android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/contact_title_view" android:layout_marginRight="0dp"/> </android.support.v4.view.PagerTitleStrip> </android.support.v4.view.ViewPager> <android.support.design.widget.FloatingActionButton android:id="@+id/fab" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="bottom|end" android:layout_margin="@dimen/fab_margin" app:srcCompat="@android:drawable/ic_dialog_email" /> </android.support.design.widget.CoordinatorLayout>
本人的ChatPageFragment的代码如下：
public class ChatPageFragment extends Fragment {
private RecyclerView recyclerView;
public RecyclerView getRecycleView(){return recyclerView;}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.chat_list_view,container,false);
this.recyclerView = (RecyclerView) view.findViewById(R.id.chat_list_view);
return view;
}
}
本人的chat_list_view的代码如下：
<android.support.v7.widget.RecyclerView xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/chat_list_view"> </android.support.v7.widget.RecyclerView>
可能没什么关系，本人的ChatPageAdapter的代码如下：
public class ChatPageAdapter extends RecyclerView.Adapter<ChatPageAdapter.ChatItemViewHolder> {
private Context mContext;
public ChatPageAdapter(Context context){
this.mContext = context;
}
@Override
public ChatItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(mContext).inflate(R.layout.chat_item,parent,false);
return new ChatItemViewHolder(view);
}
@Override
public void onBindViewHolder(ChatItemViewHolder holder, int position) {
//TODO:add holder behavior to adjust the data from the internet
}
@Override
public int getItemCount() {
return 3;
}
class ChatItemViewHolder extends RecyclerView.ViewHolder {
ImageView mImageView;
TextView mPersonName;
TextView mChatContext;
TextView mData;
public ChatItemViewHolder(View itemView) {
super(itemView);
mImageView = (ImageView) itemView.findViewById(R.id.chat_item_person);
mPersonName = (TextView) itemView.findViewById(R.id.chat_item_person_name);
mChatContext = (TextView) itemView.findViewById(R.id.chat_item_context);
mData = (TextView) itemView.findViewById(R.id.chat_item_data);
}
}
}
本人的log如下：
FATAL EXCEPTION: main
Process: com.f1993xuboss.musicpark, PID: 2633
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.f1993xuboss.musicpark/com.f1993xuboss.musicpark.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method “void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)” on a null object reference
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method “void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)” on a null object reference
at com.f1993xuboss.musicpark.MainActivity.initView(MainActivity.java:64)
at com.f1993xuboss.musicpark.MainActivity.onCreate(MainActivity.java:51)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
本人试了一下，网上说的常规方法是findViewById的方法不行，原因是本人activity_main.xml中没包含，所以本人想在fragment函数中获取，但是屡试屡败，高手们有什么解决方法吗？或换个思路也行。
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mChatRecycleView.setLayoutManager(new LinearLayoutManager(getActivity())); mChatRecycleView.setAdapter(new ChatPageAdapter(getActivity()
));
