我在尝试什么
我想深入了解JSON。为此,我想我为我的Youtube频道创建了一个应用程序。首先,我在这个网站上创建了我的频道的JSON文件:GDataYoutube,并创建了这个JSON文件:频道的JSON。
在那之后,我开始用这个教程创建我的频道应用程序:JSON教程,我对它做了一些修改,认为它"应该"与我的频道JSON文件一起使用,但它就是不起作用,我真的不明白为什么,这是我一直收到的错误消息。11-22 08:35:37.932: E/CANT READ DATA(15923): Error parsing data org.json.JSONException: Value Response of type java.lang.String cannot be converted to JSONObject
问题是JSONfunction.java的代码在教程中起作用,这里没有,所以main.java中一定有问题,但我不知道是错的。!!:(
问题
我需要在Main.java中更改什么才能使代码正常工作。如果你有我得到的问题的教程,或者一个非常好的代码示例,我也会很高兴。通道中的JSON文件如下所示:JSON结构你可以在这里找到代码和错误日志:
代码
JSON功能.java
package de.stepforward;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.HashMap;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.util.Log;
public class JSONfunction {
public static JSONObject getJSONfromURL(String url){
InputStream is = null;
String result = "";
JSONObject jArray = null;
//http post
try{
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(url);
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
}catch(Exception e){
Log.e("NO CONNECTION", "Error in http connection "+e.toString());
}
//convert response to string
try{
BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "n");
}
is.close();
result=sb.toString();
}catch(Exception e){
Log.e("CANT CONVERT DATA", "Error converting result "+e.toString());
}
try{
jArray = new JSONObject(result);
}catch(JSONException e){
Log.e("CANT READ DATA", "Error parsing data "+e.toString());
}
return jArray;
}
}
ShowChannel.java
package de.stepforward;
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;
public class ShowChannel extends ListActivity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();
JSONObject json = JSONfunction.getJSONfromURL("http://gdata.youtube.com/feeds/mobile/users/TheStepForward/uploads?alt=json&format=1");
try{
JSONObject feed = json.getJSONObject("feed");
JSONArray entry = feed.getJSONArray("entry");
for(int i=0;i<entry.length();i++){
HashMap<String, String> map = new HashMap<String, String>();
JSONObject e = entry.getJSONObject(i);
map.put("title", e.getString("title.$t"));
map.put("description", e.getString("content.$t"));
map.put("link", e.getString("media$player"));
map.put("thumbnail", e.getString("media$thumbnail.url"));
mylist.add(map);
}
}catch(JSONException e) {
Log.e("log_tag", "Error parsing data "+e.toString());
}
//Liste füllen
ListAdapter adapter = new SimpleAdapter(this, mylist , R.layout.listlayout,
new String[] {"thumbnail", "title", "description", "link" },
new int[] { R.id.img_video, R.id.txt_title, R.id.txt_subtitle });
setListAdapter(adapter);
//OnItemClickListner für Hyperlinks
final ListView lv = getListView();
lv.setTextFilterEnabled(true);
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
@SuppressWarnings("unchecked")
HashMap<String, String> o = (HashMap<String, String>) lv.getItemAtPosition(position);
Toast.makeText(ShowChannel.this, "Link '" + o.get("link") + "' was clicked.", Toast.LENGTH_SHORT).show();
}
});
}
}
错误日志
11-22 08:35:37.932: E/CANT READ DATA(15923): Error parsing data org.json.JSONException: Value Response of type java.lang.String cannot be converted to JSONObject
11-22 08:35:37.932: D/AndroidRuntime(15923): Shutting down VM
11-22 08:35:37.932: W/dalvikvm(15923): threadid=1: thread exiting with uncaught exception (group=0x4001d5a0)
11-22 08:35:38.032: E/AndroidRuntime(15923): FATAL EXCEPTION: main
11-22 08:35:38.032: E/AndroidRuntime(15923): java.lang.RuntimeException: Unable to start activity ComponentInfo{de.stepforward/de.stepforward.ShowChannel}: java.lang.NullPointerException
11-22 08:35:38.032: E/AndroidRuntime(15923): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1816)
11-22 08:35:38.032: E/AndroidRuntime(15923): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1837)
11-22 08:35:38.032: E/AndroidRuntime(15923): at android.app.ActivityThread.access$1500(ActivityThread.java:132)
11-22 08:35:38.032: E/AndroidRuntime(15923): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1033)
11-22 08:35:38.032: E/AndroidRuntime(15923): at android.os.Handler.dispatchMessage(Handler.java:99)
11-22 08:35:38.032: E/AndroidRuntime(15923): at android.os.Looper.loop(Looper.java:143)
11-22 08:35:38.032: E/AndroidRuntime(15923): at android.app.ActivityThread.main(ActivityThread.java:4196)
11-22 08:35:38.032: E/AndroidRuntime(15923): at java.lang.reflect.Method.invokeNative(Native Method)
11-22 08:35:38.032: E/AndroidRuntime(15923): at java.lang.reflect.Method.invoke(Method.java:507)
11-22 08:35:38.032: E/AndroidRuntime(15923): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
11-22 08:35:38.032: E/AndroidRuntime(15923): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
11-22 08:35:38.032: E/AndroidRuntime(15923): at dalvik.system.NativeStart.main(Native Method)
11-22 08:35:38.032: E/AndroidRuntime(15923): Caused by: java.lang.NullPointerException
11-22 08:35:38.032: E/AndroidRuntime(15923): at de.stepforward.ShowChannel.onCreate(ShowChannel.java:36)
11-22 08:35:38.032: E/AndroidRuntime(15923): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)
11-22 08:35:38.032: E/AndroidRuntime(15923): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1780)
11-22 08:35:38.032: E/AndroidRuntime(15923): ... 11 more
谢谢你提前提供的帮助最佳再订单safari
为了强调用户370305的观点(作为单独的答案发布,因为注释中的多行代码不容易阅读(:
// No good.
String notJsonObject = "This is not a JSON object.";
JSONObject jsonObject = new JSONObject(notJsonObject);
// Good.
String validJsonObject = "{"foo":"bar"}";
JSONObject jsonObject = new JSONObject(validJsonObject);