执行多行SQLite查询

我想从互联网上下载一个.txt文件，然后读取它并执行它。我已成功下载，阅读并执行单行查询文件。但问题是我不能从文件执行多行查询。我做了一些研究，他们不适合我的需求，所以我想出了一个解决方案，但我不能找出一些错误。我的想法是将.txt文件逐行转换为List，然后对List中的每个String执行sqlite中的查询。这里是我的一些代码：执行多行SQLite查询

public void updateDB(View v){ 

    new DownloadFileFromURL().execute(file_url); 

    File file = new File(Environment 
      .getExternalStorageDirectory().toString() 
      + "/update.txt") 

    Log.i("UPDATE", "SQL DOWNLOADED"); 

    while(start.equals(true)){ 

     List<String> list = readUpdate2("update.txt"); 
     for (String string : list) { 
      datasource.executeRaw(string); 
      Log.i("UPDATE", "EXEC SQL # : " + list.size()); 
     } 

    file.delete();}} 

public List<String> readUpdate2(String url){ 
    File sdcard = Environment.getExternalStorageDirectory(); 
    //Get the text file 
    List<String> list = null; 
     File file = new File(sdcard,url); 

     try { 

     BufferedReader br = new BufferedReader(new FileReader(file)); 
     String line; 

      while((line = br.readLine()) != null) { 
         // this is where the error happens : 
       list.add(line); 
       Log.i("UPDATE", "LINE : " + line); 
      } 
     } 
     catch (IOException e) { 
     } 
     return list; 
}

问题是我坚持一个空指针异常。它说这条线是空的。这里是logcat的：

03-30 18:01:18.965: E/AndroidRuntime(12474): FATAL EXCEPTION: main 
03-30 18:01:18.965: E/AndroidRuntime(12474): java.lang.IllegalStateException: Could not execute method of the activity 
03-30 18:01:18.965: E/AndroidRuntime(12474): at android.view.View$1.onClick(View.java:3838) 
03-30 18:01:18.965: E/AndroidRuntime(12474): at android.view.View.performClick(View.java:4475) 
03-30 18:01:18.965: E/AndroidRuntime(12474): at android.view.View$PerformClick.run(View.java:18786) 
03-30 18:01:18.965: E/AndroidRuntime(12474): at android.os.Handler.handleCallback(Handler.java:730) 
03-30 18:01:18.965: E/AndroidRuntime(12474): at android.os.Handler.dispatchMessage(Handler.java:92) 
03-30 18:01:18.965: E/AndroidRuntime(12474): at android.os.Looper.loop(Looper.java:137) 
03-30 18:01:18.965: E/AndroidRuntime(12474): at android.app.ActivityThread.main(ActivityThread.java:5493) 
03-30 18:01:18.965: E/AndroidRuntime(12474): at java.lang.reflect.Method.invokeNative(Native Method) 
03-30 18:01:18.965: E/AndroidRuntime(12474): at java.lang.reflect.Method.invoke(Method.java:525) 
03-30 18:01:18.965: E/AndroidRuntime(12474): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1209) 
03-30 18:01:18.965: E/AndroidRuntime(12474): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1025) 
03-30 18:01:18.965: E/AndroidRuntime(12474): at dalvik.system.NativeStart.main(Native Method) 
03-30 18:01:18.965: E/AndroidRuntime(12474): Caused by: java.lang.reflect.InvocationTargetException 
03-30 18:01:18.965: E/AndroidRuntime(12474): at java.lang.reflect.Method.invokeNative(Native Method) 
03-30 18:01:18.965: E/AndroidRuntime(12474): at java.lang.reflect.Method.invoke(Method.java:525) 
03-30 18:01:18.965: E/AndroidRuntime(12474): at android.view.View$1.onClick(View.java:3833) 
03-30 18:01:18.965: E/AndroidRuntime(12474): ... 11 more 
03-30 18:01:18.965: E/AndroidRuntime(12474): Caused by: java.lang.NullPointerException 
03-30 18:01:18.965: E/AndroidRuntime(12474): at com.meemarbashi.meemardictionary.UpdateActivity.readUpdate2(UpdateActivity.java:292) 
03-30 18:01:18.965: E/AndroidRuntime(12474): at com.meemarbashi.meemardictionary.UpdateActivity.updateDB(UpdateActivity.java:223) 
03-30 18:01:18.965: E/AndroidRuntime(12474): ... 14 more

所以基本上我没有得到从.txt文件的文本，然后我不能进入我的列表添加任何东西。我该怎么办？

在此先感谢

来源

2014-03-30 KababChi

这可能是空指针异常的原因：

List<String> list = null;

尝试分配一个新的列表，而不是空的

来源

2014-03-30 14:04:10 Y2i

“+1”感谢的人！这是一个简单的错误：D – KababChi

执行多行SQLite查询

回答

相关问题