我正在制作一个应用程序，该应用程序在导航抽屉中使用回收视图。为什么回收视图的内容没有显示出来。视图肯定存在，因为我可以看到滚动阴影。我不确定我做错了什么，因为应用程序运行时没有崩溃。
导航抽屉片段：
public class NavigationDrawerFragment extends android.support.v4.app.Fragment {
public static final String PREF_FILE_NAME = "testPref";
public static final String KEY_USER_LEARNED_DRAWER = "user_learned_drawer";
private RecyclerView mRecyclerView;
private ActionBarDrawerToggle mDrawerToggle;
private DrawerLayout mDrawerLayout;
private View containerView;
private Boolean mUserLearnedDrawer;
private Boolean mFromSavedInstanceState;
private DrawerAdapter adapter;
public NavigationDrawerFragment() {
mFromSavedInstanceState = false;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mUserLearnedDrawer = Boolean.valueOf(readFromPreferences(getActivity(), KEY_USER_LEARNED_DRAWER, "false"));
if (savedInstanceState != null){
mFromSavedInstanceState = true;
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View layout = inflater.inflate(R.layout.fragment_navigation_drawer, container, false);
mRecyclerView = (RecyclerView) layout.findViewById(R.id.drawerList);
adapter = new DrawerAdapter(getActivity(), getData());
mRecyclerView.setAdapter(adapter);
mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
return layout;
}
public static List<DrawerRow> getData(){
List<DrawerRow> data = new ArrayList<>();
int icons[] = {R.drawable.ic_launcher,R.drawable.ic_launcher,R.drawable.ic_launcher,R.drawable.ic_launcher};
String titles[] = {"Link 1","Link 2","Link 3","Link 4"};
for (int i = 0 ; i < titles.length && i < icons.length; i++){
DrawerRow current = new DrawerRow();
current.iconId = icons[i];
current.title = titles[i];
data.add(current);
}
return data;
}
public void setUp(int fragmentId, DrawerLayout drawerLayout, Toolbar toolbar) {
containerView = getActivity().findViewById(fragmentId);
mDrawerLayout = drawerLayout;
mDrawerToggle = new ActionBarDrawerToggle(getActivity(), drawerLayout, toolbar, R.string.drawerOpen, R.string.drawerClosed){
@Override
public void onDrawerOpened(View drawerView) {
super.onDrawerOpened(drawerView);
if(!mUserLearnedDrawer){
mUserLearnedDrawer = true;
saveToPreferences(getActivity(),KEY_USER_LEARNED_DRAWER, mUserLearnedDrawer+"");
}
getActivity().invalidateOptionsMenu();
}
@Override
public void onDrawerClosed(View drawerView) {
super.onDrawerClosed(drawerView);
getActivity().invalidateOptionsMenu();
}
};
if(!mUserLearnedDrawer && !mFromSavedInstanceState){
mDrawerLayout.openDrawer(containerView);
}
mDrawerLayout.setDrawerListener(mDrawerToggle);
mDrawerLayout.post(new Runnable() {
@Override
public void run() {
mDrawerToggle.syncState();
}
});
}
public void saveToPreferences(Context context, String prefName, String prefValue){
SharedPreferences sharedPreferences = context.getSharedPreferences(PREF_FILE_NAME, Context.MODE_PRIVATE);
SharedPreferences.Editor mEditor = sharedPreferences.edit();
mEditor.putString(prefName, prefValue);
mEditor.apply();
}
public static String readFromPreferences(Context context, String prefName, String defaultValue){
SharedPreferences sharedPreferences = context.getSharedPreferences(PREF_FILE_NAME, Context.MODE_PRIVATE);
return sharedPreferences.getString(prefName,defaultValue);
}
}
适配器:
public class DrawerAdapter extends RecyclerView.Adapter<DrawerAdapter.MyViewHolder>{
private LayoutInflater inflator;
List<DrawerRow> data = Collections.EMPTY_LIST;
public DrawerAdapter(FragmentActivity activity, List<DrawerRow> data) {
inflator = LayoutInflater.from(activity);
this.data = data;
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View view = inflator.inflate(R.layout.nav_drawer_row , viewGroup,false);
MyViewHolder holder = new MyViewHolder(view);
return holder;
}
@Override
public void onBindViewHolder(MyViewHolder viewHolder, int i) {
DrawerRow current = data.get(i);
viewHolder.title.setText(current.title);
viewHolder.icon.setImageResource(current.iconId);
}
@Override
public int getItemCount() {
return 0;
}
class MyViewHolder extends RecyclerView.ViewHolder{
ImageView icon;
TextView title;
public MyViewHolder(View itemView) {
super(itemView);
icon = (ImageView) itemView.findViewById(R.id.list_icon);
title = (TextView) itemView.findViewById(R.id.list_text);
}
}
}
抽屉行：
public class DrawerRow {
int iconId;
String title;
}
布局：
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/drawerLayout">
<!--Main Content -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<include
android:id="@+id/app_bar"
layout="@layout/app_bar" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="New Text" />
</LinearLayout>
<!--Nav Drawer -->
<fragment
android:layout_width="@dimen/nav_drawer_width"
android:layout_height="match_parent"
android:layout_gravity="start"
android:name="uk.co.clickcomputing.hhscweatherstation.NavigationDrawerFragment"
android:id="@+id/fragment_navigation_drawer"/>
</android.support.v4.widget.DrawerLayout>
抽屉行：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal" android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:padding="@dimen/list_padding"
android:id="@+id/list_icon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:src="@drawable/ic_launcher"/>
<TextView
android:padding="@dimen/list_padding"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:text="New Text"
android:id="@+id/list_text" />
</LinearLayout>
导航抽屉片段布局：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#eee"
android:orientation="vertical">
<ImageView
android:layout_width="match_parent"
android:layout_height="140dp"
android:layout_marginBottom="8dp"
android:contentDescription="@string/nav_drawer_img_desciption"
android:scaleType="centerCrop"
android:src="@drawable/nav_drawer" />
<android.support.v7.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/drawerList">
</android.support.v7.widget.RecyclerView>
</LinearLayout>