我花了一整天时间试图解决这个问题，但我做不到。
在我的Android应用程序中，我有一个mainActivity HomePageServices，它有3个选项卡：HomeActivity，ProfileActivity和SettingsActivity。
这些标签是由TabLayout和ViewPager调用的片段。 选项卡之间的过渡完美，但问题是我没有任何片段显示！
我想在HomeActivity中显示带有GridLayout卡片的RecyclerView。
这是我到目前为止所做的：
HomePageServices ：
public class HomePageServices extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ActionBar actionBar = getSupportActionBar();
actionBar.hide();
//Toolbar
initCollapsingToolbar();
//tabs
TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
final ViewPager viewPager = (ViewPager) findViewById(R.id.pager);
final PagerAdapter adapter = new PagerAdapter
(getSupportFragmentManager(), tabLayout.getTabCount());
viewPager.setAdapter(adapter);
viewPager.addOnPageChangeListener(new
TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
@Override
public void onTabSelected(TabLayout.Tab tab) {
viewPager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(TabLayout.Tab tab) {
}
@Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
}
/**
* Initializing collapsing toolbar
* Will show and hide the toolbar title on scroll
*/
private void initCollapsingToolbar() {
final CollapsingToolbarLayout collapsingToolbar =
(CollapsingToolbarLayout) findViewById(R.id.collapsing_toolbar);
collapsingToolbar.setTitle(" ");
AppBarLayout appBarLayout = (AppBarLayout) findViewById(R.id.appbar);
appBarLayout.setExpanded(true);
// hiding & showing the title when toolbar expanded & collapsed
appBarLayout.addOnOffsetChangedListener(new AppBarLayout.OnOffsetChangedListener() {
boolean isShow = false;
int scrollRange = -1;
@Override
public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
if (scrollRange == -1) {
scrollRange = appBarLayout.getTotalScrollRange();
}
if (scrollRange + verticalOffset == 0) {
collapsingToolbar.setTitle(getString(R.string.app_name));
isShow = true;
} else if (isShow) {
collapsingToolbar.setTitle(" ");
isShow = false;
}
}
});
}
}
HomePageServices XML布局：
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/main_content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/white"
android:fitsSystemWindows="true"
>
<android.support.design.widget.AppBarLayout
android:id="@+id/appbar"
android:layout_width="match_parent"
android:layout_height="@dimen/detail_backdrop_height"
android:fitsSystemWindows="true"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
<android.support.design.widget.CollapsingToolbarLayout
android:id="@+id/collapsing_toolbar"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
app:contentScrim="?attr/colorPrimary"
app:expandedTitleMarginEnd="64dp"
app:expandedTitleMarginStart="48dp"
app:expandedTitleTextAppearance="@android:color/transparent"
app:layout_scrollFlags="scroll|exitUntilCollapsed">
<RelativeLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<ImageView
android:id="@+id/backdrop"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
android:scaleType="centerCrop"
app:layout_collapseMode="parallax"
android:layout_alignParentTop="true"
android:layout_alignParentStart="true" />
<TextView
android:id="@+id/love_music"
android:layout_width="237dp"
android:layout_height="wrap_content"
android:text="@string/backdrop_title"
android:textColor="@android:color/white"
android:textSize="@dimen/backdrop_title"
android:gravity="center_horizontal|center"
android:layout_gravity="center_horizontal|center"
android:layout_centerHorizontal="true" />
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_collapseMode="pin"
app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
android:layout_centerVertical="true">
<android.support.design.widget.TabLayout
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:id="@+id/tab_layout">
<android.support.design.widget.TabItem
android:icon="@drawable/ic_home_white_24dp"
android:layout_height="match_parent"
android:layout_width="match_parent"/>
<android.support.design.widget.TabItem
android:icon="@drawable/ic_perm_identity_white_24dp"
android:layout_height="match_parent"
android:layout_width="match_parent"/>
<android.support.design.widget.TabItem
android:icon="@drawable/ic_settings_white_24dp"
android:layout_height="match_parent"
android:layout_width="match_parent"/>
</android.support.design.widget.TabLayout>
<android.support.v4.view.ViewPager
android:id="@+id/pager"
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:layout_below="@id/tab_layout"
app:layout_behavior="@string/appbar_scrolling_view_behavior"/>
</android.support.v7.widget.Toolbar>
</RelativeLayout>
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
</android.support.design.widget.CoordinatorLayout>
PagerAdapter：
public class PagerAdapter extends FragmentStatePagerAdapter {
int mNumOfTabs;
public PagerAdapter(FragmentManager fm, int NumOfTabs) {
super(fm);
this.mNumOfTabs = NumOfTabs;
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
ProfileActivity tab1 = new ProfileActivity();
return tab1;
case 1:
SettingsActivity tab2 = new SettingsActivity();
return tab2;
case 2:
HomeActivity tab3=new HomeActivity();
return tab3;
default:
return null;
}
}
@Override
public int getCount() {
return mNumOfTabs;
}
}
HomeActivity
public class HomeActivity extends Fragment {
private RecyclerView recyclerView;
public static ServicesAdapter homeAdapter;
public static List<Service> serviceList;
final static String ADD_NEW_ITEM_TYPE="add new item";
public HomeActivity () {
//empty constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
//cards
View rootView=inflater.inflate(R.layout.activity_home2, container, false);
TextView tt= (TextView) rootView.findViewById(R.id.textView3);
recyclerView = (RecyclerView) rootView.findViewById(R.id.recycler_view);
serviceList = new ArrayList<>();
homeAdapter = new ServicesAdapter(this.getContext(), serviceList);
RecyclerView.LayoutManager mLayoutManager = new GridLayoutManager(getActivity(), 2);
recyclerView.setLayoutManager(mLayoutManager);
recyclerView.addItemDecoration(new GridSpacingItemDecoration(2, dpToPx(10), true));
recyclerView.setItemAnimator(new DefaultItemAnimator());
initServices();
recyclerView.setAdapter(homeAdapter);
Log.d("show me what you got", serviceList.toString());
Toast.makeText(this.getContext(),"Hiiiiiiiiiiiiiiii from the other side",Toast.LENGTH_SHORT).show();
return rootView;
}
public static class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {
int spanCount;
int spacing;
boolean includeEdge;
public GridSpacingItemDecoration(int spanCount, int spacing, boolean includeEdge) {
this.spanCount = spanCount;
this.spacing = spacing;
this.includeEdge = includeEdge;
}
}
private int dpToPx(int dp) {
Resources r = getResources();
return Math.round(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, r.getDisplayMetrics()));
}
public void initServices () {
Service a = new Service(ADD_NEW_ITEM_TYPE);
serviceList.add(a);
//just for testing
a = new Service("Signaler a dysfonctionnement");
serviceList.add(a);
a = new Service("Activités inter-employés");
serviceList.add(a);
homeAdapter.notifyDataSetChanged();
}
}
HomeActivity XML布局：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_home2"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="HomeActivity">
<include layout="@layout/content_main"
/>
<TextView
android:text="TextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:layout_alignParentStart="true"
android:layout_marginStart="42dp"
android:id="@+id/textView3" />
</RelativeLayout>
最后是 RecyclerView 布局：
<RelativeLayout 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"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="HomePage.HomeActivity"
tools:showIn="@layout/activity_home2">
<android.support.v7.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:clipToPadding="false"
android:scrollbars="vertical"
android:paddingLeft="5dp" />
</RelativeLayout>
PS ：在创建标签之前，RecyclerViewer成功地在活动中显示了卡片而没有任何问题。