java.lang.String kann nicht in org.json.JSONObject umgewandelt werden - Laufzeitfehler

Question

Ich habe eine App, an der ich arbeite, bestehend aus 3 Aktivitäten. Die ersten 2 Aktivitäten funktionieren gut. das Problem aufkommt, wenn die dritte Aktivität aus einer Liste genannt wird (die von einer Klasse erzeugt wird, die AsyncTask und eine Liste Adapter erstreckt)

Der Code für die dritte Aktivität unterhalb

package com.dozie.destiny.usda; 

import android.app.ProgressDialog; 
import android.content.Context; 
import android.net.ConnectivityManager; 
import android.net.NetworkInfo; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.support.multidex.MultiDex; 
import android.support.v7.app.AppCompatActivity; 
import android.widget.TextView; 
import android.widget.Toast; 

import org.json.JSONArray; 
import org.json.JSONException; 
import org.json.JSONObject; 

import java.io.IOException; 
import java.util.ArrayList; 
import java.util.List; 

import okhttp3.OkHttpClient; 
import okhttp3.Request; 
import okhttp3.Response; 

public class Detailed extends AppCompatActivity { 

boolean connected = false; 

    @Override 
    protected void attachBaseContext(Context base) { 
     super.attachBaseContext(base); 
     MultiDex.install(this); 
    } 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_detailed); 

     String id= getIntent().getStringExtra("id"); 
     getarticle GetArticle = new getarticle(); 
     GetArticle.execute(new String[]{"https://api.nal.usda.gov/pubag/rest/articles/"+"60609"+"/?api_key=DEMO_KEY"}); 

    } 

    public void toaster(String message){ 
     Toast.makeText(Detailed.this, message, Toast.LENGTH_LONG).show(); 
    } 
    public void networkcheck() { 

     ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE); 
     if (connectivityManager.getNetworkInfo(connectivityManager.TYPE_MOBILE).getState() == NetworkInfo.State.CONNECTED) { 
      connected = true; 
     } 
     if (connectivityManager.getNetworkInfo(connectivityManager.TYPE_WIFI).getState() == NetworkInfo.State.CONNECTED) { 
      connected = true; 

     } 
    } 





    private class getarticle extends AsyncTask<String, Void, String> { 

     private ProgressDialog pDialog; 
     List<String> authorname = new ArrayList<>(); 

     //this method is called before download starts. we can display a 'loading' status here 
     protected void onPreExecute() { 
      super.onPreExecute(); 

      pDialog = new ProgressDialog(Detailed.this); 
      pDialog.setMessage("Loading Details..."); 
      pDialog.setCancelable(false); 
      pDialog.show(); 

     } 

     protected String doInBackground(String... urls) { 
      OkHttpClient client = new OkHttpClient(); 
      Request request = new Request.Builder().url(urls[0]).build(); 

      try { 
       Response response = client.newCall(request).execute(); 
       if (response.isSuccessful()) { 
        return response.body().string(); 
       } 

      } catch (IOException e) { 
       e.printStackTrace(); 
       String message = "Unable to Load Details from Database"; 
       toaster(message); 
       return message; 

      } 

      String message = "Unable to Load Details from Database"; 
      toaster(message); 
      return message; 

     } 




     protected void onPostExecute(String result) { 

      try { 
       JSONObject MyJsonObject = new JSONObject(result); 
       JSONArray ResultArray = MyJsonObject.getJSONArray("authors"); 


       for (int i = 0; i < ResultArray.length(); i++) { 
        JSONObject ResultObject = (JSONObject) ResultArray.get(i); // accessing each item in the array 

        authorname.add(ResultObject.toString()+"\n"); 

       } 
       String title = MyJsonObject.getString("title"); 
       String source = MyJsonObject.getString("source"); 
       String abstracts = MyJsonObject.getString("abstract"); 
       String url = MyJsonObject.getString("url"); 


       TextView titled = (TextView) findViewById(R.id.titledetail); 
       TextView authord = (TextView) findViewById(R.id.authorsdetail); 
       TextView abstractd = (TextView) findViewById(R.id.abstractdetail); 
       TextView urld = (TextView) findViewById(R.id.linkdetail); 
       TextView sourced = (TextView) findViewById(R.id.sourcedetail); 

       titled.setText(title); 
       authord.setText(authorname.toString()); 
       abstractd.setText(abstracts); 
       sourced.setText(source); 
       urld.setText(url); 



      } catch (JSONException e) { 
       e.printStackTrace(); 
       String message = "An error occurred while loading data from database"; 
       toaster(message); 
      } 
     } 
    } 
} 

in dem zweiten Aktivitäts

Die Layout-Datei unter

<?xml version="1.0" encoding="utf-8"?> 
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:id="@+id/activity_detailed" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    tools:context="com.dozie.destiny.usda.Detailed"> 

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

     <ImageView 
      android:padding="5dp" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:src="@drawable/logo1"/> 


     <TextView 
      android:id="@+id/titledetail" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:fontFamily="sans-serif-condensed" 
      android:text="This is the title" 
      android:textSize="20sp" /> 

     <TextView 
      android:id="@+id/authorsdetail" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" /> 

     <TextView 
      android:id="@+id/abstractdetail" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" /> 


     <TextView 
      android:id="@+id/sourcedetail" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" /> 

     <TextView 
      android:text="LINK" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" /> 


     <TextView 
      android:id="@+id/linkdetail" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:textStyle="italic" 
      android:clickable="true" 
      android:onClick="linkclicked"/> 



    </LinearLayout> 

</ScrollView> 

Mein Logcat unter

08/10 14:43:36: Launching app 
No apk changes detected since last installation, skipping installation of C:\Users\Destiny\AndroidStudioProjects\USDA\app\build\outputs\apk\app-debug.apk 
$ adb shell am force-stop com.dozie.destiny.usda 
$ adb shell am start -n "com.dozie.destiny.usda/com.dozie.destiny.usda.MainActivity" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER 
Connected to process 7251 on device emulator-5554 
W/dalvikvm: VFY: unable to find class referenced in signature (Landroid/view/SearchEvent;) 
I/dalvikvm: Could not find method android.view.Window$Callback.onSearchRequested, referenced from method android.support.v7.view.WindowCallbackWrapper.onSearchRequested 
W/dalvikvm: VFY: unable to resolve interface method 15984: Landroid/view/Window$Callback;.onSearchRequested (Landroid/view/SearchEvent;)Z 
D/dalvikvm: VFY: replacing opcode 0x72 at 0x0006 
I/dalvikvm: Could not find method android.view.Window$Callback.onWindowStartingActionMode, referenced from method android.support.v7.view.WindowCallbackWrapper.onWindowStartingActionMode 
W/dalvikvm: VFY: unable to resolve interface method 15988: Landroid/view/Window$Callback;.onWindowStartingActionMode (Landroid/view/ActionMode$Callback;I)Landroid/view/ActionMode; 
D/dalvikvm: VFY: replacing opcode 0x72 at 0x0008 
I/dalvikvm: Could not find method android.content.res.TypedArray.getChangingConfigurations, referenced from method android.support.v7.widget.TintTypedArray.getChangingConfigurations 
W/dalvikvm: VFY: unable to resolve virtual method 454: Landroid/content/res/TypedArray;.getChangingConfigurations()I 
D/dalvikvm: VFY: replacing opcode 0x6e at 0x0004 
I/dalvikvm: Could not find method android.content.res.TypedArray.getType, referenced from method android.support.v7.widget.TintTypedArray.getType 
W/dalvikvm: VFY: unable to resolve virtual method 476: Landroid/content/res/TypedArray;.getType (I)I 
D/dalvikvm: VFY: replacing opcode 0x6e at 0x0006 
I/dalvikvm: Could not find method android.content.res.Resources.getDrawable, referenced from method android.support.v7.widget.ResourcesWrapper.getDrawable 
W/dalvikvm: VFY: unable to resolve virtual method 417: Landroid/content/res/Resources;.getDrawable (ILandroid/content/res/Resources$Theme;)Landroid/graphics/drawable/Drawable; 
D/dalvikvm: VFY: replacing opcode 0x6e at 0x0008 
I/dalvikvm: Could not find method android.content.res.Resources.getDrawableForDensity, referenced from method android.support.v7.widget.ResourcesWrapper.getDrawableForDensity 
W/dalvikvm: VFY: unable to resolve virtual method 419: Landroid/content/res/Resources;.getDrawableForDensity (IILandroid/content/res/Resources$Theme;)Landroid/graphics/drawable/Drawable; 
D/dalvikvm: VFY: replacing opcode 0x6e at 0x000a 
D/dalvikvm: GC_FOR_ALLOC freed 181K, 19% free 3117K/3828K, paused 0ms, total 0ms 
I/PGA: Attempting to create new SOCKET connectionn pid = 7251, tid = 7251 
I/PGA: New SOCKET connection: com.dozie.destiny.usda (pid 7251, tid 7251) 
I/Choreographer: Skipped 31 frames! The application may be doing too much work on its main thread. 
W/dalvikvm: VFY: unable to find class referenced in signature (Ljava/nio/file/Path;) 
W/dalvikvm: VFY: unable to find class referenced in signature ([Ljava/nio/file/OpenOption;) 
I/dalvikvm: Could not find method java.nio.file.Files.newOutputStream, referenced from method okio.Okio.sink 
W/dalvikvm: VFY: unable to resolve static method 22313: Ljava/nio/file/Files;.newOutputStream (Ljava/nio/file/Path;[Ljava/nio/file/OpenOption;)Ljava/io/OutputStream; 
D/dalvikvm: VFY: replacing opcode 0x71 at 0x0012 
W/dalvikvm: VFY: unable to find class referenced in signature (Ljava/nio/file/Path;) 
W/dalvikvm: VFY: unable to find class referenced in signature ([Ljava/nio/file/OpenOption;) 
I/dalvikvm: Could not find method java.nio.file.Files.newInputStream, referenced from method okio.Okio.source 
W/dalvikvm: VFY: unable to resolve static method 22312: Ljava/nio/file/Files;.newInputStream (Ljava/nio/file/Path;[Ljava/nio/file/OpenOption;)Ljava/io/InputStream; 
D/dalvikvm: VFY: replacing opcode 0x71 at 0x0012 
I/Choreographer: Skipped 30 frames! The application may be doing too much work on its main thread. 
D/dalvikvm: GC_FOR_ALLOC freed 433K, 12% free 3562K/4028K, paused 30ms, total 30ms 
I/MultiDex: VM with version 1.6.0 does not have multidex support 
I/MultiDex: install 
I/MultiDex: MultiDexExtractor.load(/data/app/com.dozie.destiny.usda-1.apk, false) 
I/MultiDex: loading existing secondary dex files 
I/MultiDex: load found 0 secondary dex files 
I/MultiDex: install done 
D/AndroidRuntime: Shutting down VM 
W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x95d97b20) 
I/Process: Sending signal. PID: 7251 SIG: 9 
D/AndroidRuntime: procName from cmdline: com.dozie.destiny.usda 
E/AndroidRuntime: in writeCrashedAppName, pkgName :com.dozie.destiny.usda 
D/AndroidRuntime: file written successfully with content: com.dozie.destiny.usda StringBuffer : ;com.dozie.destiny.usda 
E/AndroidRuntime: FATAL EXCEPTION: main 
        Process: com.dozie.destiny.usda, PID: 7251 
        java.lang.ClassCastException: java.lang.String cannot be cast to org.json.JSONObject 
         at com.dozie.destiny.usda.Detailed$getarticle.onPostExecute(Detailed.java:117) 
         at com.dozie.destiny.usda.Detailed$getarticle.onPostExecute(Detailed.java:66) 
         at android.os.AsyncTask.finish(AsyncTask.java:632) 
Application terminated. 

Jungs, ich brauche deine Hilfe wirklich, ich bin fest

Answer 1

Sie versuchen, einen String zu einem JSONObject auf JSONObject ResultObject = (JSONObject) ResultArray.get(i); zu werfen, da ResultArray.get(i) einen String zurückgibt. Dies ist jedoch nicht möglich.

Versuchen Sie dies innerhalb onPostExecute:

for (int i = 0; i < ResultArray.length(); i++) { 
       JSONObject ResultObject = ResultArray.getJSONObject(i); // accessing each item in the array 

       authorname.add(ResultObject.toString()+"\n"); 

      } 

Answer 2

for (int i = 0; i < ResultArray.length(); i++) { 
       JSONObject ResultObject = ResultArray.getJSONObject(i); // accessing each item in the array 

       authorname.add(ResultObject.toString()+"\n"); 

      } 

Ich habe erkannt, dass ich einen String Array für ein Objekt Array im JSON-Datenstrom verkannt. Es sollte für ihre Antworten

for (int i = 0; i < ResultArray.length(); i++) { 
        String ResultObject = (String) ResultArray.get(i); // accessing each item in the array 

        authorname.add(ResultObject.toString()+"\n"); 

       } 

Eine Kopie von dem, was die JSON-Stream sieht aus wie unten

{ 
    "version":"2.0", 
    "id":"60609", 
    "agid":"60609", 
    "title":"Properties of extruded chia - corn meal puffs", 
    "authors":[ 
     "Jeffrey A Byars", 
     "Mukti Singh" 
    ], 
    "source":"LWT - food science and technology 2015 v.62 no.1, Part 2 pp. 506-510", 
    "subjects":[ 
     "corn meal", 
     "energy", 
     "extrusion", 
     "fatty acids", 
     "food processing", 
     "grinding", 
     "hardness", 
     "heat", 
     "seeds", 
     "temperature", 
     "water content" 
    ], 
    "url":"http://dx.doi.org/10.1016/j.lwt.2014.06.036", 
    "abstract":"This study investigated the properties of extruded corn meal puffs containing chia. Mixtures of corn meal and chia seeds (0-20 g/100 g) were processed in a laboratory-scale twin-screw extruder at different moisture contents (18-22 g/100 g) and final heating zone temperatures (120-160°C). Extrusion processing provides a simple method for grinding the seeds, which is necessary for making the fatty acids available. The expansion of cylindrical extrudates decreased with increasing chia content, increasing moisture and increasing final heating zone temperature. The hardness of the extrudates increased with increasing moisture content and decreased at intermediate chia levels. The specific mechanical energy of the extrusion process decreased with increasing chia content." 
} 

Vielen Dank an alle sein, ich es wirklich schätzen