Android RecyclerView卡未显示`

Question

I am new to Android. I have moved heaven and earth to get my app to show RecyclerView with Cards but am not able to,no matter what. Tried a lot of searching on Google and StackOverflow and also on a lot of recommended sites. My code is as follows:

HomeActivity.java

public class HomeActivity extends AppCompatActivity {
    ...
    private RecyclerView mRecyclerView;
    protected void onCreate(Bundle savedInstanceState) {
        ...
        mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
        TransactionRecyclerViewAdapter adapter=new TransactionRecyclerViewAdapter(this, getDataSet());
        mRecyclerView.setAdapter(adapter);
        mRecyclerView.setHasFixedSize(true);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        ...
    }


    private ArrayList<FavoriteTransaction> getDataSet() {
        ArrayList results = new ArrayList<FavoriteTransaction>();

        FavoriteTransaction favoriteTransaction1 = new FavoriteTransaction();
        favoriteTransaction1.setAmount("11");
        favoriteTransaction1.setBody("11 ka recharge");
        results.add(favoriteTransaction1);

        FavoriteTransaction favoriteTransaction2 = new FavoriteTransaction();
        favoriteTransaction2.setAmount("12");
        favoriteTransaction2.setBody("12 ka recharge");
        results.add(favoriteTransaction2);

        FavoriteTransaction favoriteTransaction3 = new FavoriteTransaction();
        favoriteTransaction3.setAmount("13");
        favoriteTransaction3.setBody("13 ka recharge");
        results.add(favoriteTransaction3);

        FavoriteTransaction favoriteTransaction4 = new FavoriteTransaction();
        favoriteTransaction4.setAmount("14");
        favoriteTransaction4.setBody("14 ka recharge");
        results.add(favoriteTransaction4);

        FavoriteTransaction favoriteTransaction5 = new FavoriteTransaction();
        favoriteTransaction5.setAmount("15");
        favoriteTransaction5.setBody("15 ka recharge");
        results.add(favoriteTransaction5);

        return results;
    }
}

activity_home.xml

<android.support.v4.widget.DrawerLayout
    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:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/colorgray">

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

        <LinearLayout
            android:id="@+id/container_toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">

            <include
                android:id="@+id/toolbar"
                layout="@layout/toolbar" />
        </LinearLayout>

        <include layout="@layout/content_home" />

    </LinearLayout>

    <android.support.design.widget.NavigationView
        android:id="@+id/nvView"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:background="@android:color/white"
        app:menu="@menu/activity_home_drawer"
        app:headerLayout="@layout/nav_header"/>

</android.support.v4.widget.DrawerLayout>

content_home.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
    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"
    xmlns:fab="http://schemas.android.com/apk/res-auto"
    android:id="@+id/container_body"
    android:layout_width="fill_parent"
    android:layout_height="0dp"
    android:layout_weight="1" >

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/scrollView"
        android:paddingBottom="55dp">

        <LinearLayout
            android:orientation="vertical"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:padding="15dp">

            <include
                android:id="@+id/card_list_fav_transact"
                layout="@layout/card_list_fav_transact"/>

        </LinearLayout>
    </ScrollView>

</FrameLayout>

card_list_fav_transact.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="10dp">

    <TextView
        android:id="@+id/info_text_sp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="@string/hdr_lbl_fav"
        android:layout_marginBottom="5dp"/>

    <android.support.v7.widget.RecyclerView
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/my_recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:clipToPadding="false"
        android:paddingBottom="16dp"
        android:paddingTop="16dp"
        android:scrollbars="vertical"
        />

</LinearLayout>

card_transaction_row.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    android:id="@+id/card_view"
    android:layout_gravity="center"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/colorwhite">
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/colorwhite">
        <TextView
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:gravity="center"
            android:text="190"
            android:textColor="@color/colorPrimary"
            android:id="@+id/tv_fav_amt"
            android:background="@drawable/stl_tv_blue_circle"
            android:textAppearance="?android:attr/textAppearanceMedium"/>
        <LinearLayout
            android:orientation="vertical"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginLeft="10dp"
            android:gravity="center_vertical"
            android:layout_toRightOf="@+id/tv_fav_amt"
            android:layout_toEndOf="@+id/tv_fav_amt">
            <TextView
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:text="Body"
                android:id="@+id/fav_body"
                android:clickable="true"
                android:background="@drawable/stl_btn_underline"/>
            <TextView
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:text="SubText"
                android:id="@+id/fav_subtext"
                android:clickable="true"
                android:background="@drawable/stl_btn_underline"/>
        </LinearLayout>
        <Button
            style="@style/Base.Widget.AppCompat.Button.Borderless"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Buy"
            android:id="@+id/btn_tr_buy"
            android:layout_centerVertical="true"
            android:layout_alignParentRight="true"
            android:layout_alignParentEnd="true"
            android:layout_marginRight="10dp"
            android:background="@drawable/stl_btn_blue"
            android:textColor="@android:color/white"/>
    </RelativeLayout>
</android.support.v7.widget.CardView>

TransactionRecyclerViewAdapter.java

public class TransactionRecyclerViewAdapter extends RecyclerView.Adapter<TransactionViewHolder> {

    private ArrayList<FavoriteTransaction> transactionList;
    private Context context;
    private LayoutInflater inflater;

    public TransactionRecyclerViewAdapter(Context context, ArrayList<FavoriteTransaction> myDataset) {
        this.transactionList = new ArrayList<>(myDataset);
        this.context = context;
        this.inflater = LayoutInflater.from(context);
    }
    @Override
    public int getItemCount() {
        return this.transactionList.size();
    }

    @Override
    public void onBindViewHolder(TransactionViewHolder contactViewHolder, int i) {
        FavoriteTransaction favTransaction = transactionList.get(i);
        contactViewHolder.tvAmount.setText(favTransaction.getAmount());
    }

    @Override
    public TransactionViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v=inflater.inflate(R.layout.card_transaction_row, parent, false);
        TransactionViewHolder viewHolder=new TransactionViewHolder(v);
        return viewHolder;
    }
}

TransactionViewHolder.java

public class TransactionViewHolder extends RecyclerView.ViewHolder  {
    TextView tvAmount, tvBody, tvSubText;
    public TransactionViewHolder(View itemView) {
        super(itemView);
        tvAmount = (TextView) itemView.findViewById(R.id.tv_fav_amt);
        tvBody = (TextView) itemView.findViewById(R.id.fav_body);
        tvSubText = (TextView) itemView.findViewById(R.id.fav_subtext);
    }
}

FavoriteTransaction.java

public class FavoriteTransaction {
    private int transactionId;
    private String amount;
    private String subText, body;

    public int getTransactionId() {
        return transactionId;
    }

    public void setTransactionId(int transactionId) {
        this.transactionId = transactionId;
    }

    public String getAmount() {
        return amount;
    }

    public void setAmount(String amount) {
        this.amount = amount;
    }

    public String getBody() {
        return body;
    }

    public void setBody(String body) {
        this.body = body;
    }

    public String getSubText() {
        return subText;
    }

    public void setSubText(String subText) {
        this.subText = subText;
    }
}

When I execute my app, I am not able to see the recycler with the cards. Can someone help me where I am going wrong. Just point me in the right direction.

Thanks in advance.

Answer 1

You wrote findViewById to the Activity class. However RecyclerView is not in your activity_home.xml , it is in nested layout.

Try defining the included layout and apply findViewById on that view, or simply define RecyclerView in your activity_home.xml

Why So?

Activity.findViewById(int id) method finds the id inside that particular Activity's layout. If you have nested layout, for example, like this activity_home.xml

<android.support.v4.widget.DrawerLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    ...
    <include
        android:id="@+id/view_card_list_fav_transact"
        layout="@layout/card_list_fav_transact"/>

</android.support.v4.widget.DrawerLayout>

and your card_list_fav_transact.xml

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="10dp">

     <android.support.v7.widget.RecyclerView
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/my_recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:clipToPadding="false"
        android:paddingBottom="16dp"
        android:paddingTop="16dp"
        android:scrollbars="vertical"/>

</LinearLayout>

Code inside your Activity will be

View includedView = findViewById(R.id.view_card_list_favt_transact);
RecyclerView rv = includedView.findViewById(R.id.my_recycler_view);

And you are all set!