onCreateDialog里面创建Dialog,组件空指针异常解决

protected Dialog onCreateDialog(int id) {
switch(id)
{
   case NEWMESSAGEDIALOG:
       LayoutInflater lf=LayoutInflater.from(this);
       final View alertView=lf.inflate(R.layout.newmessagedialog, null);
       final ImageButton newMessageIB=(ImageButton) alertView.findViewById(R.id.newmessageSearch);
       final EditText newMessageNumber=(EditText) alertView.findViewById(R.id.newmessageNumber);
       final EditText newMessageNeiRong=(EditText) alertView.findViewById(R.id.newmessageEditText);
       final AlertDialog.Builder newMessageDialog=new AlertDialog.Builder(this);
   
       newMessageDialog.setView(alertView);
       newMessageDialog.setTitle(this.getResources().getString(R.string.newMessage_Title));

       newMessageDialog.setPositiveButton(this.getResources().getString(R.string.sentbutton), new DialogInterface.OnClickListener(){

@Override
public void onClick(DialogInterface arg0, int arg1) {
if(newMessageNumber.getText().toString().equals(""))
{
Toast.makeText(InBoxActivity.this, R.string.numberIsNull, Toast.LENGTH_SHORT).show();
   return;
}
else if(newMessageNeiRong.getText().toString().equals(""))
{
Toast.makeText(InBoxActivity.this, R.string.messageIsNull, Toast.LENGTH_SHORT).show();
   return;
}
//    MyAsyncTask task=new MyAsyncTask();
}});
       return newMessageDialog.create();
}
return super.onCreateDialog(id);
}



之前用了this.findViewById应该改为final ImageButton newMessageIB=(ImageButton) alertView.findViewById(R.id.newmessageSearch);