Android获取所有联系人重复的名称

Im using this code:

我用这个代码：

protected String getContactInfo() {
         Cursor cursor = getContentResolver().query(ContactsContract.Data.CONTENT_URI, null, null, null, null);
         String str = "";
         while (cursor.moveToNext()) {
          str += cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME)) + ", ";
        }
        cursor.close();
        return str;
}
protected Strin