Android应用程序无法正常工作

Question

当我简单的android java解析应用程序无法正常工作时出现错误。它只显示“错误”文本（捕获异常）而不是页面的单个元素。过滤器是好的，因为应用程序正在其他模拟器上工作，但现在我不记得该AVD的规格。

package com.example.untitled5; 

import android.app.Activity; 
import android.os.Bundle; 
import android.widget.TextView; 
import org.jsoup.Jsoup; 
import org.jsoup.nodes.Document; 
import org.jsoup.select.Elements; 

public class MyActivity extends Activity { 
    /** 
    * Called when the activity is first created. 
    */ 
    static final String BLOG_URL = "[here is correct link]"; 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     // set layout view 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 
     // process 
     try { 
      ((TextView)findViewById(R.id.tv)).setText(getBlogStats()); 
     } catch (Exception ex) { 
      ((TextView)findViewById(R.id.tv)).setText("Error"); 
     } 
    } 
    protected String getBlogStats() throws Exception { 
     String result = ""; 
     // get html document structure 
     Document document = Jsoup.connect(BLOG_URL).get(); 
     // selector query 
     //while (!document.) 
     Elements nodeBlogStats = document.select(".ttElement"); 
     // check results 
     if(nodeBlogStats.size() > 0) { 
      // get value 
      result = nodeBlogStats.get(0).text(); 
     } 

     // return 
     return result; 
    } 
} 

AndroidManifest：

<uses-sdk 
     android:minSdkVersion="10" 
     android:targetSdkVersion="19"/> 
    <permission android:name="android.permission.INTERNET"/> 
    <application 
     android:label="@string/app_name"> 
     <activity 
      android:name="MyActivity" 
      android:label="@string/app_name"> 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN"/> 
       <category android:name="android.intent.category.LAUNCHER"/> 
      </intent-filter> 
     </activity> 
    </application> 
</manifest> 

main.xml中：

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
       android:orientation="vertical" 
       android:layout_width="fill_parent" 
       android:layout_height="fill_parent" 
    > 

    <TextView 
     android:id="@+id/tv" 
     android:layout_width="fill_parent" 
     android:layout_height="wrap_content" 
     /> 
</LinearLayout> 

logcat的：

02-18 20:34:38.021  91-130/system_process I/ActivityManager﹕ Displayed com.example.untitled5/.MyActivity: +2s702ms 
02-18 20:34:43.221  390-390/com.android.defcontainer D/dalvikvm﹕ GC_EXPLICIT freed 6K, 54% free 2537K/5511K, external 1625K/2137K, paused 46ms 
02-18 20:34:47.537  91-204/system_process D/SntpClient﹕ request time failed: java.net.SocketException: Address family not supported by protocol 

更新：稍返工码Wi TH你的暗示

public class MyActivity extends Activity { 
    /** 
    * Called when the activity is first created. 
    */ 
    static final String BLOG_URL = "link"; 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     // set layout view 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 
     // async task start 
     new FillText().execute(); 
    } 
    private class FillText extends AsyncTask <Void, Void, String> { 

     @Override 
     protected String doInBackground(Void... params) { 
      String result = ""; 

      // get html document structure 
      Document document = null; 
      try { 
       document = Jsoup.connect(BLOG_URL).get(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 
      // selector query 
      Elements nodeBlogStats = document.select(".ttElement"); 
      // check results 
      if(nodeBlogStats.size() > 0) { 
       // get value 
       result = nodeBlogStats.get(0).text(); 
      } 

      // return 
      return result; 
     } 
     @Override 
     protected void onPostExecute(String myText){ 
      super.onPostExecute(myText); 
      ((TextView)findViewById(R.id.tv)).setText(doInBackground()); 
     } 
    } 
} 

现在我得到一个错误：

02-18 23:17:26.371  688-697/com.example.untitled5 E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #1 
    java.lang.RuntimeException: An error occured while executing doInBackground() 
      at android.os.AsyncTask$3.done(AsyncTask.java:200) 
      at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274) 
      at java.util.concurrent.FutureTask.setException(FutureTask.java:125) 
      at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308) 
      at java.util.concurrent.FutureTask.run(FutureTask.java:138) 
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088) 
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581) 
      at java.lang.Thread.run(Thread.java:1019) 
    Caused by: java.lang.NullPointerException 
      at com.example.untitled5.MyActivity$FillText.doInBackground(MyActivity.java:40) 
      at com.example.untitled5.MyActivity$FillText.doInBackground(MyActivity.java:26) 

Answer 1

也许你的错误可能在getBlogStats（）涉及到延迟JSON请求的内部

您应该使用AsyncTask来填充textview ..类似这样的东西

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 

    .... 

    // AsyncTask start 
    new FillText().execute(); 

    .. 

} 

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

    @Override 
    protected String doInBackground(Void... params) { 
     String result = ""; 
     // get html document structure 
     Document document = Jsoup.connect(BLOG_URL).get(); 
     // selector query 
     //while (!document.) 
     Elements nodeBlogStats = document.select(".ttElement"); 
     // check results 
     if(nodeBlogStats.size() > 0) { 
      // get value 
      result = nodeBlogStats.get(0).text(); 
     } 

     // return 
     return result; 
    } 

    @Override 
    protected void onPostExecute(String myText) { 
     super.onPostExecute(myText); 

     if(!myText.equals("")) 
      ((TextView)findViewById(R.id.tv)).setText(myText); 
    } 
} 

再见