如何在onProgressUpdate()中更新listview

Question

我是android的新手,我想获取联系人并在列表视图中显示.这是我在asynctask.please中获取联系人的代码,帮助我们在获取每个联系人后更新列表视图.

protected Void doInBackground(Void... params) {
         ContentResolver cr = ReadContactsActivity.this.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));
                 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 phone = pCur.getString(
                                  pCur.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
                        //li.add("Name:"+name+",Number:"+phone);
                           publishProgress("Name:"+name+",Number:"+phone);
                     }
                     pCur.close();
                     }
                 }
             }
        return null;
    }


    // A callback method executed on UI thread, invoked by the publishProgress() 
    // from doInBackground() method
    @Override
    protected void onProgressUpdate(String... values) {
         list=(ListView) findViewById(R.id.lvDisplay);
        ArrayAdapter<String> adp=new ArrayAdapter<String> 
        (getBaseContext(),R.layout.list,R.id.label,li);
        list.setAdapter(adp);       
    }

Answer 1

您如何使用列表视图和适配器非常合适.

• 不要每次都使用findViewById,而是存储对它的引用
• 不要每次都设置新的适配器,而是更改基础数据并调用

• 总是做你的一次设置(获取listview的参考,初始化适配器等..)in OnPreExecute

  ListView list;
  List<String> names;
  ArrayAdapter<string> adapter;
  
  @Override
  protected void onPreExecute() {
      names = new ArrayList<String>();
      list = (ListView) findViewById(R.id.lvDisplay);
      ArrayAdapter<String> adapter = new ArrayAdapter<String>     
          (getBaseContext(),
           R.layout.list,
           R.id.label,
           names);
      list.setAdapter(adp);  
  }
  
  // doInBackground() ...
  
  @Override
  protected void onProgressUpdate(String... values) {
       names.add(values[0])
       adapter.notifyDataSetChanged();
  }
  

注意:在这种情况下,我实际上建议您保留适配器,listView和AsyncTask 之外的基础数据的引用.您仍然可以使用这些引用,并且还可以在需要时在外部类中使用它们(很可能)