RecyclerView不会显示任何内容

Question

我希望使用CardView将RecyclerView显示为数据列表。但我得到了空白屏幕（RecyclerView部分）。我想显示一些文字和图片。

CheeseDetailActivityexp.java

public class CheeseDetailActivityexp extends AppCompatActivity implements  GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener,LocationListener {

    public static final String EXTRA_NAME = "cheese_name";

    private static LatLng def_latlng=new LatLng(12.0,77.0);
    private LatLng mLocation;
    private Marker mLocationMarker;

    private SupportMapFragment mMapFragment;

    private GoogleMap mMap;
    private boolean mIsNeedLocationUpdate = true;

    private GoogleApiClient mGoogleApiClient;
    private LocationRequest mLocationRequest;
    RecyclerView mRecyclerView;
    RecyclerView.LayoutManager mLayoutManager;
    CardAdapter mAdapter;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_detail);

        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addApi(LocationServices.API)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .build();
        setUpMapIfNeeded();

        Intent intent = getIntent();
        final String cheeseName = intent.getStringExtra(EXTRA_NAME);

        final Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        CollapsingToolbarLayout collapsingToolbar =
                (CollapsingToolbarLayout) findViewById(R.id.collapsing_toolbar);
        collapsingToolbar.setTitle("");
        mRecyclerView = (RecyclerView) findViewById(R.id.recyclerview);

        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));

        mAdapter = new CardAdapter();
        mRecyclerView.setAdapter(mAdapter);

      //  loadBackdrop();
    }



    /* @Override
     public boolean onCreateOptionsMenu(Menu menu) {
         getMenuInflater().inflate(R.menu.sample_actions, menu);
         return true;
     }*/
    private void setUpMapIfNeeded() {
        // Do a null check to confirm that we have not already instantiated the map.
        if (mMap == null) {
            // Try to obtain the map from the SupportMapFragment.
            mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.main_activity_mapview))
                    .getMap();

            if (mMap != null) {
                setUpMap();
            }

        }}

    private void setUpMap() {
        mMap.setMyLocationEnabled(true);
        mMap.getUiSettings().setCompassEnabled(true);
        mMap.getUiSettings().setMyLocationButtonEnabled(true);
        // Check if we were successful in obtaining the map.
        LocationManager lm = (LocationManager) getApplicationContext().getSystemService(Context.LOCATION_SERVICE);
        if (!(lm.isProviderEnabled(LocationManager.GPS_PROVIDER)))
            moveToLocation(def_latlng);
        LatLng update = getLastKnownLocation();

        if (update != null) {
            CameraPosition cameraPosition = new CameraPosition.Builder().target(
                    new LatLng(12.845351,77.66105)).zoom(12).build();

            mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));



        }
        CameraPosition cameraPosition = new CameraPosition.Builder().target(
                new LatLng(12.845351,77.66105)).zoom(20).build();

        mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));
        mMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker"));
    }
    protected void onResume() {
        super.onResume();
        setUpMapIfNeeded();
    }
        private LatLng getLastKnownLocation() {
            return getLastKnownLocation(true);
        }

        private LatLng getLastKnownLocation(boolean isMoveMarker) {
            LocationManager lm = (LocationManager) getApplicationContext().getSystemService(Context.LOCATION_SERVICE);
            Criteria criteria = new Criteria();
            criteria.setAccuracy(Criteria.ACCURACY_LOW);
            String provider = lm.getBestProvider(criteria, true);

            if (provider == null) {
                return null;
            }
            Location loc = lm.getLastKnownLocation(provider);
            if (loc != null) {
                LatLng latLng = new LatLng(loc.getLatitude(), loc.getLongitude());

                return latLng;
            }
            return null;
        }
    private void moveToLocation(Location location) {
        if (location == null) {
            return;
        }
        LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
        moveToLocation(latLng);
    }

    private void moveToLocation(LatLng latLng) {
        moveToLocation(latLng, true);
    }

    private void moveToLocation(LatLng latLng, final boolean moveCamera) {
        if (latLng == null) {
            return;
        }
        mLocation = latLng;
      /*  mListView.post(new Runnable() {
            @Override
            public void run() {
                if (mMap != null && moveCamera) {
                    mMap.moveCamera(CameraUpdateFactory.newCameraPosition(CameraPosition.fromLatLngZoom(mLocation, 11.0f)));
                }
            }
        });*/
    }
    @Override
    public void onLocationChanged(Location location) {
        if (mIsNeedLocationUpdate) {
            moveToLocation(location);
        }
    }

    @Override
    public void onConnected(Bundle bundle) {
        mLocationRequest = LocationRequest.create();
        mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
        mLocationRequest.setNumUpdates(1);

        LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
    }

    @Override
    public void onConnectionSuspended(int i) {

    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {

    }
    public void onStart() {
        super.onStart();
        // Connect the client.
        mGoogleApiClient.connect();
    }

    @Override
    public void onStop() {
        // Disconnecting the client invalidates it.
        mGoogleApiClient.disconnect();
        super.onStop();
    }

}

cardAdapter代码

public class CardAdapter extends RecyclerView.Adapter<CardAdapter.ViewHolder> {

    ArrayList<BusRouteNameDetails> mItems;

    public CardAdapter() {
        super();
        mItems = new ArrayList<>();
        BusRouteNameDetails routename = new BusRouteNameDetails();
        routename.setName("GopalanMall-Siemens");
        routename.setNumber("S4");

        mItems.add(routename);

        routename = new BusRouteNameDetails();
        routename.setName("GopalanMall-Siemens");
        routename.setNumber("S4");

        mItems.add(routename);

        routename = new BusRouteNameDetails();
        routename.setName("GopalanMall-Siemens");
        routename.setNumber("S4");

        mItems.add(routename);

        routename = new BusRouteNameDetails();
        routename.setName("GopalanMall-Siemens");
        routename.setNumber("S4");

        mItems.add(routename);


        routename = new BusRouteNameDetails();
        routename.setName("GopalanMall-Siemens");
        routename.setNumber("S4");

        mItems.add(routename);
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
        View v = LayoutInflater.from(viewGroup.getContext())
                .inflate(R.layout.busroutename_list, viewGroup, false);
        ViewHolder viewHolder = new ViewHolder(v);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(ViewHolder viewHolder, int i) {
        BusRouteNameDetails routename = mItems.get(i);
        viewHolder.tvName.setText(routename.getName());
        viewHolder.tvRoutename.setText(routename.getNumber());
    }

    @Override
    public int getItemCount() {
        return mItems.size();
    }

    class ViewHolder extends RecyclerView.ViewHolder{


        public TextView tvName;
        public TextView tvRoutename;

        public ViewHolder(View itemView) {
            super(itemView);

            tvName = (TextView)itemView.findViewById(R.id.RouteName1);
            tvRoutename = (TextView)itemView.findViewById(R.id.Route_src_dest);
        }
    }
}

getter / setters活动

public class BusRouteNameDetails {
    private String mName;
    private String mNumber;

    public String getName() {
        return mName;
    }

    public void setName(String name) {
        this.mName = name;
    }

    public String getNumber() {
        return mNumber;
    }

    public void setNumber(String Number) {
        this.mNumber = Number;
    }
}

主要活动* .xml      

<android.support.design.widget.AppBarLayout
    android:id="@+id/appbar"
    android:layout_width="match_parent"
    android:layout_height="@dimen/detail_backdrop_height"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
    android:fitsSystemWindows="true">

    <android.support.design.widget.CollapsingToolbarLayout
        android:id="@+id/collapsing_toolbar"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_scrollFlags="scroll|exitUntilCollapsed"
        android:fitsSystemWindows="true"
        app:contentScrim="?attr/colorPrimary"
        app:expandedTitleMarginStart="48dp"
        app:expandedTitleMarginEnd="64dp">

        <fragment
            android:id="@+id/main_activity_mapview"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:clickable="true"
            class="com.google.android.gms.maps.SupportMapFragment"
            app:layout_collapseMode="parallax"
            android:fitsSystemWindows="true"
            />


        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
            app:layout_collapseMode="pin" />

    </android.support.design.widget.CollapsingToolbarLayout>

</android.support.design.widget.AppBarLayout>

   <!-- <android.support.v4.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">-->
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingTop="400dp">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />
</LinearLayout>


<android.support.design.widget.FloatingActionButton
    android:layout_height="wrap_content"
    android:layout_width="wrap_content"
    app:layout_anchor="@id/appbar"
    app:layout_anchorGravity="bottom|right|end"
    android:src="@drawable/ic_discuss"
    android:layout_margin="@dimen/fab_margin"
    android:clickable="true"/>

</android.support.design.widget.CoordinatorLayout>

最后是cardview xml

<?xml version="1.0" encoding="utf-8"?>
 <RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

<android.support.v7.widget.CardView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    card_view:cardCornerRadius="3dp"
    android:layout_marginTop="9dp"
    android:layout_marginLeft="9dp"
    android:layout_marginRight="9dp"
    card_view:cardElevation="0.01dp"
    android:layout_marginBottom="0dp">

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical">


        <LinearLayout

            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            android:background="@drawable/border">
            <ImageView
                android:layout_width="24dp"
                android:layout_height="24dp"
                android:padding="2dp"
                android:src="@drawable/rsz_bus_symbol"/>

            <TextView
                android:padding="2dp"
                android:textStyle="bold"
                android:id="@+id/RouteName1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"/>
            <TextView
                android:paddingLeft="10dp"
                android:textStyle="bold"
                android:id="@+id/Route_src_dest"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                />
        </LinearLayout>

</LinearLayout>
</android.support.v7.widget.CardView>
</RelativeLayout>

我在哪里做错了？

Answer 1

所以这就是答案

<android.support.design.widget.AppBarLayout
android:id="@+id/appbar"
android:layout_width="match_parent"
android:layout_height="@dimen/detail_backdrop_height"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
android:fitsSystemWindows="true">

<android.support.design.widget.CollapsingToolbarLayout
    android:id="@+id/collapsing_toolbar"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_scrollFlags="scroll|exitUntilCollapsed"
    android:fitsSystemWindows="true"
    app:contentScrim="?attr/colorPrimary"
    app:expandedTitleMarginStart="48dp"
    app:expandedTitleMarginEnd="64dp">

    <fragment
        android:id="@+id/main_activity_mapview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:clickable="true"
        class="com.google.android.gms.maps.SupportMapFragment"
        app:layout_collapseMode="parallax"
        android:fitsSystemWindows="true"
        />


    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
        app:layout_collapseMode="pin" />

</android.support.design.widget.CollapsingToolbarLayout>

</android.support.design.widget.AppBarLayout>
<android.support.v7.widget.RecyclerView
    android:id="@+id/recyclerview"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    />



<android.support.design.widget.FloatingActionButton
android:layout_height="wrap_content"
android:layout_width="wrap_content"
app:layout_anchor="@id/appbar"
app:layout_anchorGravity="bottom|right|end"
android:src="@drawable/ic_discuss"
android:layout_margin="@dimen/fab_margin"
android:clickable="true"/>

</android.support.design.widget.CoordinatorLayout>

只需删除LinearLayout

即可