我正在尝试使用 JSON 和 Retrofit 库在 Recyclerview 中通过 CardViews 显示我的提要。 我已经解决这个问题 4 个小时，现在在 google 上搜索 1 个小时，但仍然没有成功。
无论我尝试什么，我都会收到以下错误:
D/错误:java.lang.IllegalStateException:预期为 BEGIN_OBJECT，但在第 1 行第 2 列路径 $ 处为 BEGIN_ARRAY
D/错误:java.lang.IllegalStateException:预期为 BEGIN_OBJECT，但在第 1 行第 2 列路径 $
PHP API 的 JSON 示例:
[{"id":"143","uploadID":"36","type":"excellent","userID":"58","username":"doitlikeaves","date":"31 May","timestamp":"2016-05-31 22:37:50","title":"PH Zusammenfassung #2","subject":"Physik"},{"id":"142","uploadID":"36","type":"presentation","userID":"58","username":"doitlikeaves","date":"31 May","timestamp":"2016-05-31 21:57:21","title":"PH Zusammenfassung #2","subject":"Physik"},{"id":"141","uploadID":"61","type":"document","userID":"56","username":"maja","date":"31 May","timestamp":"2016-05-31 14:29:00","title":" Rev.","subject":"Geschichte"}]
Android 文件:
FeedElement.js:
import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;
public class FeedElement {
@SerializedName("id")
@Expose
private String id;
@SerializedName("uploadID")
@Expose
private String uploadID;
@SerializedName("type")
@Expose
private String type;
@SerializedName("userID")
@Expose
private String userID;
@SerializedName("username")
@Expose
private String username;
@SerializedName("date")
@Expose
private String date;
@SerializedName("timestamp")
@Expose
private String timestamp;
@SerializedName("title")
@Expose
private String title;
@SerializedName("subject")
@Expose
private String subject;
/**
*
* @return
* The id
*/
public String getId() {
return id;
}
/**
*
* @param id
* The id
*/
public void setId(String id) {
this.id = id;
}
/**
*
* @return
* The uploadID
*/
public String getUploadID() {
return uploadID;
}
/**
*
* @param uploadID
* The uploadID
*/
public void setUploadID(String uploadID) {
this.uploadID = uploadID;
}
/**
*
* @return
* The type
*/
public String getType() {
return type;
}
/**
*
* @param type
* The type
*/
public void setType(String type) {
this.type = type;
}
/**
*
* @return
* The userID
*/
public String getUserID() {
return userID;
}
/**
*
* @param userID
* The userID
*/
public void setUserID(String userID) {
this.userID = userID;
}
/**
*
* @return
* The username
*/
public String getUsername() {
return username;
}
/**
*
* @param username
* The username
*/
public void setUsername(String username) {
this.username = username;
}
/**
*
* @return
* The date
*/
public String getDate() {
return date;
}
/**
*
* @param date
* The date
*/
public void setDate(String date) {
this.date = date;
}
/**
*
* @return
* The timestamp
*/
public String getTimestamp() {
return timestamp;
}
/**
*
* @param timestamp
* The timestamp
*/
public void setTimestamp(String timestamp) {
this.timestamp = timestamp;
}
/**
*
* @return
* The title
*/
public String getTitle() {
return title;
}
/**
*
* @param title
* The title
*/
public void setTitle(String title) {
this.title = title;
}
/**
*
* @return
* The subject
*/
public String getSubject() {
return subject;
}
/**
*
* @param subject
* The subject
*/
public void setSubject(String subject) {
this.subject = subject;
}
}
JSONResponseFeed.js:
import java.util.ArrayList;
public class JSONResponseFeed {
private ArrayList<FeedElement> feeds;
/**
* @return The feeds
*/
public ArrayList<FeedElement> getFeed() {
return feeds;
}
}
RequestInterfaceFeed.js:
import retrofit2.Call;
import retrofit2.http.GET;
import retrofit2.http.Query;
public interface RequestInterfaceFeed {
@GET("getFeed")
Call<JSONResponseFeed> getJSON(@Query("key") String apiKey);
}
DataAdapterFeed.js:
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import java.util.List;
public class DataAdapterFeed extends RecyclerView.Adapter<DataAdapterFeed.ViewHolder> {
private List<FeedElement> feed;
public DataAdapterFeed(List<FeedElement> feed) {
this.feed = feed;
}
@Override
public DataAdapterFeed.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.card_row, viewGroup, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(DataAdapterFeed.ViewHolder viewHolder, int i) {
viewHolder.tv_name.setText(feed.get(i).getUsername());
}
@Override
public int getItemCount() {
return feed.size();
}
public class ViewHolder extends RecyclerView.ViewHolder{
private TextView tv_name;
public ViewHolder(View view) {
super(view);
tv_name = (TextView)view.findViewById(R.id.username);
}
}
}
MainActivity.js 中的函数:
private void loadJSON(){
final String url = "https://mydomainiscorrect.justreplacedithere/api/v1/";
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(url)
.addConverterFactory(GsonConverterFactory.create())
.build();
final RequestInterfaceFeed request = retrofit.create(RequestInterfaceFeed.class);
Call<JSONResponseFeed> call = request.getJSON(apiKey);
call.enqueue(new Callback<JSONResponseFeed>() {
@Override
public void onResponse(Call<JSONResponseFeed> call, retrofit2.Response<JSONResponseFeed> response) {
List<FeedElement> data = response.body().getFeed();
adapter = new DataAdapterFeed(data);
recyclerView.setAdapter(adapter);
}
@Override
public void onFailure(Call<JSONResponseFeed> call, Throwable t) {
Log.d("Error", t.getMessage());
}
});
}
private void initViews(){
recyclerView = (RecyclerView)findViewById(R.id.card_recycler_view);
recyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getApplicationContext());
recyclerView.setLayoutManager(layoutManager);
loadJSON();
}
如果需要 - cardView.xml:
<android.support.v7.widget.CardView
xmlns:card_view="http://schemas.android.com/apk/res-auto"
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:layout_marginLeft="5dp"
android:layout_marginRight="5dp"
card_view:cardCornerRadius="5dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="10dp"
android:orientation="vertical">
<TextView
android:id="@+id/username"
android:layout_marginTop="10dp"
android:layout_marginBottom="10dp"
android:textSize="18sp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textStyle="bold" />
</LinearLayout>
MainActivity RecyclerView XML:
<android.support.v7.widget.RecyclerView
android:id="@+id/card_recycler_view"
android:scrollbars="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
我对 Java 和 Android 编程还很陌生，我对 PHP 很了解，但 Java 有时确实让我头疼。
非常感谢您对我的帮助，我真的很感激!
最佳答案
不需要 JSONResponseFeed。更新RequestInterfaceFeed
public interface RequestInterfaceFeed {
@GET("getFeed")
Call<List<FeedElement>> getJSON(@Query("key") String apiKey);
}
并更新loadJSON方法
private void loadJSON(){
final String url = "https://mydomainiscorrect.justreplacedithere/api/v1/";
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(url)
.addConverterFactory(GsonConverterFactory.create())
.build();
final RequestInterfaceFeed request = retrofit.create(RequestInterfaceFeed.class);
Call<List<FeedElement>> call = request.getJSON(apiKey);
call.enqueue(new Callback<List<FeedElement>>() {
@Override
public void onResponse(Call<List<FeedElement>> call, retrofit2.Response<List<FeedElement>> response) {
List<FeedElement> data = response.body();
adapter = new DataAdapterFeed(data);
recyclerView.setAdapter(adapter);
}
@Override
public void onFailure(Call<List<FeedElement>> call, Throwable t) {
Log.d("Error", t.getMessage());
}
});
}
关于java - 尝试通过改造解析 JSON Feed 时出现 IllegalStateException，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/38574193/