如何使用 AsyncTask 在 Android 中显示联系人? [英] How to display contacts in Android using AsyncTask?

问题描述

我正在尝试列出移动设备中的所有联系人.到目前为止一切正常，但是当我想到在 AsyncTask 中运行我的代码时，我在屏幕上什么也没有看到.

I'm trying to list all the contacts in mobile. So far everything was working fine, but when I thought of running my code in AsyncTask I'm getting nothing on screen.

这是代码片段

protected void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_call_list);

    lvCallList = (ListView) findViewById(R.id.lv_call_list);

    new AsyncTask<Void, Void, Void>() 
    {
        @Override
        protected void onPreExecute() 
        {
            pd = ProgressDialog.show(CallListActivity.this,
                    "Loading..", "Please Wait", true, false);
        }// End of onPreExecute method

        @Override
        protected Void doInBackground(Void... params) 
        {
            getContacts();

            return null;
        }// End of doInBackground method

        @Override
        protected void onPostExecute(Void result)
        {
            pd.dismiss();

            lvCallList.setAdapter(new CustomAdapter(CallListActivity.this));

        }//End of onPostExecute method
    }.execute((Void[]) null);
     count = this.displayContactName.size();
    thumbnailsselection = new boolean[count];
}


private void getContacts()
{
    ContentResolver cr = getContentResolver();
    Cursor cur = cr.query(ContactsContract.Contacts.CONTENT_URI, null,null, null, null);
    if (cur.getCount() > 0)
    {
        while (cur.moveToNext())
        {
            String id = cur.getString(cur.getColumnIndex(ContactsContract.Contacts._ID));
            String name = cur.getString(cur.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));

            this.displayContactName.add(name);
            if (Integer.parseInt(cur.getString(cur.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER))) > 0)
            {
                Cursor pCur = cr.query( ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
                                        null,
                                        ContactsContract.CommonDataKinds.Phone.CONTACT_ID +" = ?", 
                                        new String[]{id}, 
                                        null);
                while (pCur.moveToNext())
                {
                    String phoneNumber = pCur.getString(pCur.getColumnIndex( ContactsContract.CommonDataKinds.Phone.NUMBER));
                    this.displayContactNumber.add(phoneNumber);
                } 
                pCur.close();
            }
        }
    }
}

 public class CustomAdapter extends BaseAdapter 
{
    /*
     * Variables Declaration section
     */
    private Context mContext;

    public CustomAdapter(Context context) 
    {
        mContext = context;
    }//End of CustomAdapter constructor

    public int getCount() 
    {
        return count;
    }//End of getCount method

    public Object getItem(int position) 
    {
        return position;
    }//End of getItem method

    public long getItemId(int position) 
    {
        return position;
    }//End of getItemId method

    public View getView(int position, View convertView, ViewGroup parent) 
    {

        return convertView;
    }//End of getView method
}//End of CustomAdapter instance inner class

class ViewHolder 
{
    TextView textviewName;
    TextView textviewNumber;
    CheckBox checkbox;
    int id;
}//End of ViewHolder instance inner class

在 pd.dismiss(); 处使用断点的

displayContactName 值是

displayContactName value using break point at pd.dismiss(); is

displayContactName  ArrayList  (id=830007844896)    
array   Object[12]  (id=830007907208)   
    [0] "Rrs" (id=830007907144) 
    [1] "Fgsd" (id=830007920424)    
    [2] null    
    [3] null    
    [4] null    
    [5] null    
    [6] null    
    [7] null    
    [8] null    
    [9] null    
    [10]    null    
    [11]    null    
modCount    2   
size    2   

我不知道我的代码有什么问题，当我不使用 AsyncTask 时，我的代码工作得很好，但是当我使用 AsyncTask 时，问题就来了.请帮我解决这个难题.

I don't know what's wrong in my code, when I don't use AsyncTask then my code works perfectly fine, but when I use AsyncTask problem comes. Please help me to solve this puzzle.

提前致谢.

推荐答案

我发现了问题，我试图在设置适配器后初始化 count，这就是问题所在，感谢 stackoverflow 和 @Raghunandan

I found out the problem, I was trying to initialise count after setting adapter, that was the problem, Thanks stackoverflow and @Raghunandan

        protected void onPostExecute(Void result)
        {
            count = displayContactName.size();
            thumbnailsselection = new boolean[count];
            lvCallList.setAdapter(new CustomAdapter(CallListActivity.this));
            pd.dismiss();
        }//End of onPostExecute method

这篇关于如何使用 AsyncTask 在 Android 中显示联系人?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！