我似乎无法连接我的适配器。我正在尝试创建Recyclerview cardview。但是，它不会显示在模拟器上。我收到一条错误消息：
E/RecyclerView：没有附加适配器;跳过布局。
这是我设置适配器的地方。
madapter = new CardAdapter( itemList, CardviewRecycler.this );
recyclerView.setAdapter(madapter);
public class CardviewRecycler extends AppCompatActivity {
// URL string to call data from myPHPAdmin localhost database.
private static final String URL_ITEMLIST = "http://192.168.240.1/ImageJsonData.php";
public RecyclerView recyclerView;
//private RecyclerView.Adapter adapter;
private CardAdapter madapter;
public List<ItemList> itemList;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_cardviewrecycler);
// Initializing ItemList Array.
itemList = new ArrayList<>();
//Calling the Recyclerview
recyclerView = findViewById(R.id.recyclerview);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
//Loading the RecyclerView data.
loadItemListData();
}
public void loadItemListData(){
StringRequest stringRequest = new StringRequest(Request.Method.GET, URL_ITEMLIST,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
//converting the string to json array object
JSONArray array = new JSONArray(response);
//traversing through all the objects
for (int i = 0; i < array.length(); i++) {
//getting item object from json array
JSONObject itemobj = array.getJSONObject(i);
int id = itemobj.getInt("id");
String image_title = itemobj.getString("image_title");
String image_url = itemobj.getString("image_url");
ItemList item = new ItemList(id, image_title, image_url);
itemList.add(item);
}
//creating adapter object and setting it to recyclerview
madapter = new CardAdapter( itemList, CardviewRecycler.this );
recyclerView.setAdapter(madapter);
} catch (JSONException e) {
e.printStackTrace();
}
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
//adding our stringrequest to queue
Volley.newRequestQueue(this).add(stringRequest);
}
}
这是我的适配器类。
public class CardAdapter extends RecyclerView.Adapter<CardAdapter.ViewHolder> {
//Bringing in the ItemList java Class.
private List<ItemList> itemList;
private Context context;
public CardAdapter(List <ItemList> itemList, Context context) {
this.itemList = itemList;
this.context = context;
}
@Override
public ViewHolder onCreateViewHolder( ViewGroup parent, int viewType) {
//Inflating the cardview.xml from the LayoutInflator parent Context.
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.cardview, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
// To bind the itemList data with the UI elements from the cardview.xml written in
//the ViewHolder subclass. The UI elements are inside the holder object.
ItemList itemlist = itemList.get(position);
//The holder object is used to bind the cardview.xml UI element to the itemList data.
holder.ImageTitleTextView.setText(itemlist.getImage());
//The holder object is binding the cardview.xml UI elementimageView to the itemList
// data using the Glide dependecy in the build.gradle file.
Glide.with(context)
.load(itemlist.getImage())
.into((ImageView) holder.itemView);
}
@Override
public int getItemCount() {
//itemList.size to show the items in the Array list.
return itemList.size();
}
class ViewHolder extends RecyclerView.ViewHolder {
//Creating UI elements from the cardview.xml
TextView ImageTitleTextView;
ImageView VollyImageView;
ViewHolder(View itemView) {
super(itemView);
//Initializing the UI elements above to Views(itemView)
ImageTitleTextView = itemView.findViewById(R.id.ImageNameTextView);
VollyImageView = itemView.findViewById(R.id.VolleyImageView);
}
}
}
这是我从myPhPadmin
中提取的物品清单数据 public class ItemList
{
private int id;
private String image_url;
private String image_title;
ItemList(int id, String image_url, String image_title) {
this.id = id;
this.image_url = image_url;
this.image_title = image_title;
}
public int getId() {
return id;
}
public String getImage() {
return image_url;
}
public String getTitle() {
return image_title;
}
}
这是我的cardview布局文件
<?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:orientation="vertical">
<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/cardview1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
card_view:cardElevation="5dp"
card_view:contentPadding="5dp"
card_view:cardCornerRadius="5dp"
card_view:cardMaxElevation="5dp">
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#ECEFF1">
<ImageView
android:id="@+id/VolleyImageView"
android:layout_width="150dp"
android:layout_height="100dp"
android:layout_marginBottom="10dp"
android:layout_marginTop="10dp"
android:scaleType="center"
android:src="@mipmap/ic_launcher"
android:contentDescription="TODO" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@+id/VolleyImageView"
android:layout_toEndOf="@+id/VolleyImageView"
android:layout_marginLeft="20dp"
android:layout_marginStart="20dp"
android:textSize="20sp"
android:textColor="#000"
android:text="@string/JSonImage"
android:id="@+id/ImageNameTextView"
android:layout_centerVertical="true"/>
</RelativeLayout>
</android.support.v7.widget.CardView>
</LinearLayout>
答案 0 :(得分：1)
您没有正确设置列表项字段。
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
ItemList itemlist = itemList.get(position);
holder.ImageTitleTextView.setText(itemlist.getTitle()); // you were setting getImage here
Glide.with(context)
.load(itemlist.getImage())
.into(holder.VollyImageView); // you were setting image on itemView which is not an ImageView.
}
您应该将wrap_content用于列表项视图。如果你放match_parent，你的一个项目将覆盖所有屏幕。
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content" //changed this
android:orientation="vertical">
E / RecyclerView：未附加适配器
这只是一个警告，你可以忽略这一点。