不幸的應用程序已停止工作

Question

我是新來android應用程序開發。我正在做這個教程的應用程序。 當我在模擬器中運行它時，它說「不幸的是AndroidJSONParsingActivity已停止工作。」 「代碼中沒有錯誤。 API級別是17，模擬器是Nexus S. 請幫我。

我從JSON tutorial

得到了教程代碼AndroidJsonParsing.java

package com.example.androidjsonparsingactivity; 

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.content.Intent; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.View; 
import android.widget.AdapterView; 
import android.widget.AdapterView.OnItemClickListener; 
import android.widget.ListAdapter; 
import android.widget.ListView; 
import android.widget.SimpleAdapter; 
import android.widget.TextView; 

public class AndroidJSONParsing extends ListActivity {  
// url to make request 
private static String url = "http://api.androidhive.info/contacts/"; 

// JSON Node names 
private static final String TAG_CONTACTS = "contacts"; 
private static final String TAG_ID = "id"; 
private static final String TAG_NAME = "name"; 
private static final String TAG_EMAIL = "email"; 
private static final String TAG_ADDRESS = "address"; 
private static final String TAG_GENDER = "gender"; 
private static final String TAG_PHONE = "phone"; 
private static final String TAG_PHONE_MOBILE = "mobile"; 
private static final String TAG_PHONE_HOME = "home"; 
private static final String TAG_PHONE_OFFICE = "office"; 

// contacts JSONArray 
JSONArray contacts = null; 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 

    // Hashmap for ListView 
    ArrayList<HashMap<String, String>> contactList = new ArrayList<HashMap<String, String>>(); 

    // Creating JSON Parser instance 
    JSONParser jParser = new JSONParser(); 

    // getting JSON string from URL 
    JSONObject json = jParser.getJSONFromUrl(url); 

    try { 
     // Getting Array of Contacts 
     contacts = json.getJSONArray(TAG_CONTACTS); 

     // looping through All Contacts 
     for(int i = 0; i < contacts.length(); i++){ 
      JSONObject c = contacts.getJSONObject(i); 

      // Storing each json item in variable 
      String id = c.getString(TAG_ID); 
      String name = c.getString(TAG_NAME); 
      String email = c.getString(TAG_EMAIL); 
      String address = c.getString(TAG_ADDRESS); 
      String gender = c.getString(TAG_GENDER); 

      // Phone number is agin JSON Object 
      JSONObject phone = c.getJSONObject(TAG_PHONE); 
      String mobile = phone.getString(TAG_PHONE_MOBILE); 
      String home = phone.getString(TAG_PHONE_HOME); 
      String office = phone.getString(TAG_PHONE_OFFICE); 

      // creating new HashMap 
      HashMap<String, String> map = new HashMap<String, String>(); 

      // adding each child node to HashMap key => value 
      map.put(TAG_ID, id); 
      map.put(TAG_NAME, name); 
      map.put(TAG_EMAIL, email); 
      map.put(TAG_PHONE_MOBILE, mobile); 

      // adding HashList to ArrayList 
      contactList.add(map); 
     } 
    } catch (JSONException e) { 
     e.printStackTrace(); 
    } 


    /** 
    * Updating parsed JSON data into ListView 
    * */ 
    ListAdapter adapter = new SimpleAdapter(this, contactList, 
      R.layout.list_item, 
      new String[] { TAG_NAME, TAG_EMAIL, TAG_PHONE_MOBILE }, new int[] { 
        R.id.name, R.id.email, R.id.mobile }); 

    setListAdapter(adapter); 

    // selecting single ListView item 
    ListView lv = getListView(); 

    // Launching new screen on Selecting Single ListItem 
    lv.setOnItemClickListener(new OnItemClickListener() { 

     @Override 
     public void onItemClick(AdapterView<?> parent, View view, 
       int position, long id) { 
      // getting values from selected ListItem 
      String name = ((TextView) view.findViewById(R.id.name)).getText().toString(); 
      String cost = ((TextView) view.findViewById(R.id.email)).getText().toString(); 
      String description = ((TextView) view.findViewById(R.id.mobile)).getText().toString(); 

      // Starting new intent 
      Intent in = new Intent(getApplicationContext(), SingleMenuItemActivity.class); 
      in.putExtra(TAG_NAME, name); 
      in.putExtra(TAG_EMAIL, cost); 
      in.putExtra(TAG_PHONE_MOBILE, description); 
      startActivity(in); 
     } 
    }); 
} 

} 

JSONParser.java

package com.example.androidjsonparsingactivity; 

import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.InputStreamReader; 
import java.io.UnsupportedEncodingException; 

import org.apache.http.HttpEntity; 
import org.apache.http.HttpResponse; 
import org.apache.http.client.ClientProtocolException; 
import org.apache.http.client.methods.HttpPost; 
import org.apache.http.impl.client.DefaultHttpClient; 
import org.json.JSONException; 
import org.json.JSONObject; 

import android.util.Log; 

public class JSONParser { 

static InputStream is = null; 
static JSONObject jObj = null; 
static String json = ""; 

// constructor 
public JSONParser() { 

} 

public JSONObject getJSONFromUrl(String url) { 

    // Making HTTP request 
    try { 
     // defaultHttpClient 
     DefaultHttpClient httpClient = new DefaultHttpClient(); 
     HttpPost httpPost = new HttpPost(url); 

     HttpResponse httpResponse = httpClient.execute(httpPost); 
     HttpEntity httpEntity = httpResponse.getEntity(); 
     is = httpEntity.getContent();    

    } catch (UnsupportedEncodingException e) { 
     e.printStackTrace(); 
    } catch (ClientProtocolException e) { 
     e.printStackTrace(); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 

    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(); 
     json = sb.toString(); 
    } catch (Exception e) { 
     Log.e("Buffer Error", "Error converting result " + e.toString()); 
    } 

    // try parse the string to a JSON object 
    try { 
     jObj = new JSONObject(json); 
    } catch (JSONException e) { 
     Log.e("JSON Parser", "Error parsing data " + e.toString()); 
    } 

    // return JSON String 
    return jObj; 

} 
} 

SingleMenuItemActivity.java

package com.example.androidjsonparsingactivity; 

import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.widget.TextView; 
public class SingleMenuItemActivity extends Activity { 

// JSON node keys 
private static final String TAG_NAME = "name"; 
private static final String TAG_EMAIL = "email"; 
private static final String TAG_PHONE_MOBILE = "mobile"; 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.single_list_item); 

    // getting intent data 
    Intent in = getIntent(); 

    // Get JSON values from previous intent 
    String name = in.getStringExtra(TAG_NAME); 
    String cost = in.getStringExtra(TAG_EMAIL); 
    String description = in.getStringExtra(TAG_PHONE_MOBILE); 

    // Displaying all values on the screen 
    TextView lblName = (TextView) findViewById(R.id.name_label); 
    TextView lblCost = (TextView) findViewById(R.id.email_label); 
    TextView lblDesc = (TextView) findViewById(R.id.mobile_label); 

    lblName.setText(name); 
    lblCost.setText(cost); 
    lblDesc.setText(description); 
} 
} 

AndroidManifest.xml中

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
package="com.example.androidjsonparsingactivity" 
android:versionCode="1" 
android:versionName="1.0" > 
<uses-permission android:name="android.permission.INTERNET" /> 

<uses-sdk 
    android:minSdkVersion="8" 
    android:targetSdkVersion="17" /> 

<application 
    android:allowBackup="true" 
    android:icon="@drawable/ic_launcher" 
    android:label="@string/app_name" 
    android:theme="@style/AppTheme" > 
    <activity 
     android:name="com.example.androidjsonparsingactivity.AndroidJSONParsing" 
     android:label="@string/app_name" > 
     <intent-filter> 
      <action android:name="android.intent.action.MAIN" /> 

      <category android:name="android.intent.category.LAUNCHER" /> 
     </intent-filter> 
    </activity> 
    <activity android:name=".SingleListItem" 
       android:label="Single Item Selected"></activity> 

</application> 


</manifest> 

logcat的

08-01 07:32:35.531: D/dalvikvm(1121): GC_FOR_ALLOC freed 42K, 7% free 2609K/2792K, paused 37ms, total 41ms 
08-01 07:32:35.541: I/dalvikvm-heap(1121): Grow heap (frag case) to 3.288MB for 635812-byte allocation 
08-01 07:32:35.591: D/dalvikvm(1121): GC_FOR_ALLOC freed 2K, 6% free 3227K/3416K, paused 47ms, total 47ms 
08-01 07:32:35.672: D/dalvikvm(1121): GC_CONCURRENT freed <1K, 6% free 3237K/3416K, paused 9ms+16ms, total 82ms 
08-01 07:32:35.740: D/AndroidRuntime(1121): Shutting down VM 
08-01 07:32:35.740: W/dalvikvm(1121): threadid=1: thread exiting with uncaught exception (group=0x40a71930) 
08-01 07:32:35.761: E/AndroidRuntime(1121): FATAL EXCEPTION: main 
08-01 07:32:35.761: E/AndroidRuntime(1121): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.androidjsonparsingactivity/com.example.androidjsonparsingactivity.AndroidJSONParsing}: android.os.NetworkOnMainThreadException 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at android.app.ActivityThread.access$600(ActivityThread.java:141) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at android.os.Handler.dispatchMessage(Handler.java:99) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at android.os.Looper.loop(Looper.java:137) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at android.app.ActivityThread.main(ActivityThread.java:5041) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at java.lang.reflect.Method.invokeNative(Native Method) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at java.lang.reflect.Method.invoke(Method.java:511) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at dalvik.system.NativeStart.main(Native Method) 
08-01 07:32:35.761: E/AndroidRuntime(1121): Caused by: android.os.NetworkOnMainThreadException 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at java.net.InetAddress.lookupHostByName(InetAddress.java:385) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at java.net.InetAddress.getAllByName(InetAddress.java:214) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at com.example.androidjsonparsingactivity.JSONParser.getJSONFromUrl(JSONParser.java:38) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at com.example.androidjsonparsingactivity.AndroidJSONParsing.onCreate(AndroidJSONParsing.java:54) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at android.app.Activity.performCreate(Activity.java:5104) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144) 
08-01 07:32:35.761: E/AndroidRuntime(1121):  ... 11 more 

Answer 1

你調用從主線程網絡。這就是爲什麼你有

Caused by: android.os.NetworkOnMainThreadException 

在android 4.0之後，你不能做它的UIThread網絡操作。你需要使用後臺線程。我寧願使用AsyncTask進行網絡通話。

希望它有助於！

Answer 2

對於Android 4.0及更高版本，您無法在UI線程上執行網絡操作，並且需要使用後臺線程。

您從主線程調用以下代碼而不是 後臺線程，因此引發此異常。

// getting JSON string from URL 
    JSONObject json = jParser.getJSONFromUrl(url); 

相反創建async task並在doInBackground異步任務

異步任務執行在背景中的opertaion的執行此（）而不是主/ UI線程上執行它的

class FetchJsonTask extends AsyncTask<Void, Void, void> { 


    protected Void doInBackground(Void... params) { 
     try { 
      // getting JSON string from URL 
     JSONObject json = jParser.getJSONFromUrl(url); 
     } catch (Exception e) { 

     } 
    } 

    protected void onPostExecute(Void result) { 
     super.onPostExecute(result); 
     //code to be executed after background task is finished 
    } 


    protected void onPreExecute() { 
     super.onPreExecute(); 
     //code to be executed before background task is started 
    } 
    return null; 
} 

在onCreate（）中，通過以下方式調用執行異步任務：

new FetchJsonTask().execute(); 

相關鏈接：

How to fix android.os.NetworkOnMainThreadException?

Answer 3

讀註釋部分，並根據該修改代碼。

class MyAsync extends AsyncTask<String, Void, Void> { 

     @Override 
     protected void onPreExecute() { 
      super.onPreExecute(); 
     } 

     @Override 
     protected Void doInBackground(String... params) { 
      // do your JSON parse here 
      return null; 
     } 

     @Override 
     protected void onPostExecute(Void result) { 
      // after gettin json data do whatever you want here 
      super.onPostExecute(result); 
     } 
    } 

打電話給你的異步類的OnCreate您爲：

new MyAsync().execute();