[英]Recycler View and Card View not displaying cards
這是我的活動:
public String id;
public String passPhrase;
public ArrayList<SongCell> songs;
private RecyclerView recyclerView;
private MyAdapter myAdapter;
private RecyclerView.LayoutManager layoutManager;
@TargetApi(Build.VERSION_CODES.JELLY_BEAN)
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.songs_view_layout);
Context context = this.getApplicationContext();
Bundle stateData = getIntent().getExtras();
try
{
id = stateData.getString("id");
passPhrase = stateData.getString("passPhrase");
ArrayList data;
recyclerView = (RecyclerView) findViewById(R.id.song_list);
recyclerView.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
data = new ArrayList<SongCell>();
for (int i=0; i<5;i++)
{
data.add(new SongCell("Song "+i,"Artist "+i, null));
}
myAdapter = new MyAdapter(data);
recyclerView.setAdapter(myAdapter);
}
catch(Exception e)
{
Log.d("Error: ", e.toString());
}
}
card.xml
<android.support.v7.widget.CardView android:layout_width="fill_parent"
android:layout_height="wrap_content"
xmlns:android="http://schemas.android.com/apk/res/android">
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:padding="6dp"
>
<ImageView
android:layout_width="70dp"
android:layout_height="70dp"
android:id="@+id/song_photo"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginRight="16dp"
android:background="@drawable/error" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/song_name"
android:textSize="30sp"
android:text="Song Name"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true"
android:textColor="#000000" />
<ImageButton
android:layout_width="60dp"
android:layout_height="60dp"
android:id="@+id/vote_button"
android:layout_alignParentRight="true"
android:layout_marginRight="8dp"
android:background="@drawable/arrow" />
</RelativeLayout>
</android.support.v7.widget.CardView>
Activity.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent"
android:background="#2d2d2d">
<TableLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TableRow
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:paddingBottom="30dp"
android:layout_marginBottom="10dp"
android:background="#222222"></TableRow>
<TableRow
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:paddingBottom="10dp">
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center">
<ImageView
android:layout_width="70dp"
android:layout_height="70dp"
android:id="@+id/featSongImage1"
android:contentDescription="@string/newsongimage"
android:background="@drawable/error" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceSmall"
android:text="@string/songname"
android:id="@+id/featSongName1" />
<ImageButton
android:layout_width="25dp"
android:layout_height="25dp"
android:id="@+id/featSongButt1"
android:background="@drawable/arrow"
android:contentDescription="@string/votearrow" />
</LinearLayout>
</TableRow>
<TableRow
android:layout_width="match_parent"
android:layout_height="match_parent"
android:foregroundGravity="fill_horizontal"
android:gravity="fill_horizontal|center">
<android.support.v7.widget.RecyclerView
android:id="@+id/song_list"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_gravity="center_horizontal" />
</TableRow>
</TableLayout>
</LinearLayout>
這是我的自定義適配器
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder>
{
private ArrayList<SongCell> data;
public MyAdapter(ArrayList<SongCell> dataI)
{
data = dataI;
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType)
{
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.song_card,viewGroup,false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(ViewHolder viewholder, int pos) {
viewholder.songName.setText(data.get(pos).getName());
viewholder.artist.setText(data.get(pos).getArtist());
viewholder.image.setImageBitmap(data.get(pos).getArtwork());
}
@Override
public int getItemCount() {
return 0;
}
@Override
public int getItemViewType(int position) {
return 0;
}
public class ViewHolder extends RecyclerView.ViewHolder
{
TextView songName;
TextView artist;
ImageView image;
ImageButton voteButton;
public ViewHolder(View v)
{
super(v);
this.songName = (TextView) v.findViewById(R.id.song_name);
this.image = (ImageView) v.findViewById(R.id.song_photo);
this.voteButton = (ImageButton) v.findViewById(R.id.vote_button);
}
}
}
我看了很多有關如何使它工作的指南,但是仍然不起作用。 任何人都知道發生了什么事嗎? 我的版本為25.0.1,並已導入所有模塊。 但這並不是在布局中添加一張卡片。
我認為調試您上傳的這么大的代碼將很困難。 但幸運的是我的視線一直在這條線上
@Override
public int getItemCount() {
return 0;
}
return 0;
在適配器中。
您的列表大小始終為0。
代替寫這個
@Override
public int getItemCount() {
return data.size();
}
編輯1:
您還將在此處獲得空指針異常
viewholder.artist.setText(data.get(pos).getArtist());
因為您沒有在ViewHolder class
初始化artist
變量。
編輯2
@Override
public int getItemCount() {
return 0;
}
您可以從適配器中刪除此特定代碼。 因為重寫我們不使用的類方法有時可能會導致您甚至無法想象的錯誤。
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