Question

我正在尝试从SQLite中检索表的row_count。我用来执行此任务的代码冻结了我的应用程序。这完全在后端运行，MainUI线程中没有任何内容。但是，我也得到了ANR错误。

这是我的代码，我在这里调用方法 -

public class del_person extends Activity{
String[] images = {}; 

 @Override 
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.del_person);
        final adapter info = new adapter(this);

   //     new del_person_Dup(null).execute();

        new Task(info).execute((Void)null);
 }
}



class Task extends AsyncTask<Void, Void, Void> {
String[] images = {}; 
adapter mAdapter; 

Task(adapter adapter)  {
   mAdapter = adapter;
}

@Override
protected Void doInBackground(Void... params) {
  // the code from the Runnable using the mAdapter instead of info.


    Log.v("distinctrowcount() is:",""+mAdapter.distinctrowcount()+"");
    Log.v("started del_person.java","started del_person.java");

    for (int i=0;i<mAdapter.distinctrowcount();i++)

{
        Log.v ("This is the "+i+"th iteration","This is the "+i+"th iteration");
    images[i] =mAdapter.getPersonList(i+1); 
    Log.v("Persons",images[i]);
}

return null;
}
}

我也尝试过使用AsyncTask。但是，我也无法摆脱这一点。

这是来自适配器类的我的distinctrowcount（）：

adapter.java：

public int distinctrowcount()
{
    int rc = 0;
    try {
        open();
        rc = mDbHelper.getdistinctrc();
        close();
    }
    catch (Exception e)
    {
        e.printStackTrace();
    }
    return rc;
}

helper.java - getdistinctrc（）：

public int getdistinctrc() {

        // TODO Auto-generated method stub

        SQLiteDatabase myDB;            
        int values = 0;
        int distinct_count = 0;
         try {
              myDB=this.openDataBase();                   
              Cursor c=myDB.rawQuery("select count (DISTINCT FileName) from Photos;",null);
              if (c != null ) {

                          String h = "";
                          while(c.moveToFirst()){
                              distinct_count = c.getInt(0);
                             //   h = c.getString(c.getColumnIndex("COUNT(*)"));
                            }

                     } 


                  if(c != null)
                 {
                         c.close();
                     myDB.close();

                  }                    
                  }catch(SQLException sqle){

                  throw sqle;

                  }
         return distinct_count;  
    }

AsyncTask代码：

class Task extends AsyncTask<Void, Void, Void> {
    String[] images = {}; 
    adapter mAdapter; 

    Task(adapter adapter)  {
       mAdapter = adapter;
    }

    @Override
    protected Void doInBackground(Void... params) {
      // the code from the Runnable using the mAdapter instead of info.


        Log.v("distinctrowcount() is:",""+mAdapter.distinctrowcount()+"");
        Log.v("started del_person.java","started del_person.java");

        for (int i=0;i<mAdapter.distinctrowcount();i++)

    {
            Log.v ("This is the "+i+"th iteration","This is the "+i+"th iteration");
        images[i] =mAdapter.getPersonList(i+1); 
        Log.v("Persons",images[i]);
    }

    return null;
}
}

除了Runnable（）和AsyncTask之外，还有其他更好的方法来实现吗？请帮我一些示例代码。

提前致谢。

Answer 1

您当前的代码不会在后台线程上运行这些数据库查询。使用AsyncTask代替：

static class Task extends AsyncTask<Void, Void, Void> {

    adapter mAdapter; 

    Task(adapter adapter)  {
       mAdapter = adapter;
    }

    @Override
    protected Void doInBackground(Void... params) {
      // the code from the Runnable using the mAdapter instead of info.
    return null;
}

在Activity的{{1}}中你会使用类似的内容：

onCreate()

ANR调用适配器类的方法时

1 个答案: