java - 在 Parse 中选择最多、第二多、第三...最近的用户

Question

我想在从解析中检索用户时执行以下操作:

1) 我只想检索该 Activity 页面的一个(我猜是 query.setLimit(1)

2)我只想检索最近的一个(我认为 query.orderByDescending("Name"); 可以做到)

在另一个 Activity 页面上，情况变得复杂

3) 我想要第二个最近的用户

在另一个 Activity 页面

4) 我想检索第三个最近的用户

在另一个 Activity 页面上 5) 我想检索第四个最近的用户

在另一个 Activity 页面上 6) 我想检索第五个最近的用户

最后，如果列表中没有找到用户，我希望他们将他们引导到另一个 Activity 页面

下面是 Activity 代码

public class Fragment1 extends Fragment {

    private String currentUserId;
    private ArrayAdapter<String> namesArrayAdapter;
    private ArrayList<String> names;
    private ListView usersListView;
    private Button logoutButton;
    String userGender = ParseUser.getCurrentUser().getString("Gender");
    String activityName = ParseUser.getCurrentUser().getString("ActivityName");
    Number maxDistance = ParseUser.getCurrentUser().getNumber("Maximum_Distance");
    String userLookingGender = ParseUser.getCurrentUser().getString("Looking_Gender");
    Number minimumAge = ParseUser.getCurrentUser().getNumber("Minimum_Age");
    Number maximumAge = ParseUser.getCurrentUser().getNumber("Maximum_Age");
    Number userage = ParseUser.getCurrentUser().getNumber("Age");

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        setConversationsList();

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment1_layout, container, false);


        return view;
    }

private void setConversationsList() {
    currentUserId = ParseUser.getCurrentUser().getObjectId();
    names = new ArrayList<String>();
    // String userActivitySelectionName = null;

    ParseQuery<ParseUser> query = ParseUser.getQuery();

    //  query.whereEqualTo("ActivityName",userActivitySelectionName);

    query.whereNotEqualTo("objectId", ParseUser.getCurrentUser().getObjectId());
    // users with Gender = currentUser.Looking_Gender
    query.whereEqualTo("Gender", userLookingGender);
    // users with Looking_Gender = currentUser.Gender
    query.whereEqualTo("Looking_Gender", userGender);
    query.setLimit(1);
    query.whereEqualTo("ActivityName", activityName);
    //query.whereGreaterThanOrEqualTo("Age", minimumAge);
    //query.whereLessThanOrEqualTo("Age", maximumAge);
    query.orderByDescending("Name");




    query.findInBackground(new FindCallback<ParseUser>() {

        public void done(List<ParseUser> userList, ParseException e) {
            if (e == null) {
                for (int i=0; i<userList.size(); i++) {
                    names.add(userList.get(i).get("Name").toString());
                    names.add(userList.get(i).get("Headline").toString());
                    names.add(userList.get(i).get("Age").toString());
                    names.add(userList.get(i).get("ActivityName").toString());


                    //       names.add(userList.get(i).getParseObject("ProfilePicture").;


                }




                usersListView = (ListView)getActivity().findViewById(R.id.userlistview);
                namesArrayAdapter =
                        new ArrayAdapter<String>(getActivity().getApplicationContext(),
                                R.layout.user_list_item, names);
                usersListView.setAdapter(namesArrayAdapter);

                usersListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                    @Override
                    public void onItemClick(AdapterView<?> a, View v, int i, long l) {
                        openConversation(names, i);
                    }
                });

            } else {
                Toast.makeText(getActivity().getApplicationContext(),
                        "Error loading user list",
                        Toast.LENGTH_LONG).show();
            }
        }
    });
}

public void openConversation(ArrayList<String> names, int pos) {
    ParseQuery<ParseUser> query = ParseUser.getQuery();
    query.whereEqualTo("Name", names.get(pos));
    query.findInBackground(new FindCallback<ParseUser>() {
        public void done(List<ParseUser> user, ParseException e) {
            if (e == null) {
                Intent intent = new Intent(getActivity().getApplicationContext(), MessagingActivity.class);
                intent.putExtra("RECIPIENT_ID", user.get(0).getObjectId());
                startActivity(intent);
            } else {
                Toast.makeText(getActivity().getApplicationContext(),
                        "Error finding that user",
                        Toast.LENGTH_SHORT).show();
            }
        }
    });
}
}

提前致谢，祝一切顺利。

Answer 1

Parse 有一个名为 .setSkip(int x) 的方法 - 该参数将跳过第一个“x”结果。如果您正在查找“第 n”个最近的用户，请设置 x = (n-1):

query.setSkip(1) // will skip the first result, giving the 2nd most recent user
query.setSkip(2) //will skip the first 2 results, giving the 3rd most recent user

...等等

另外，如果你想要最近的用户，Parse给出了一个查询方法.findFirstInBackground:

ParseQuery<ParseObject> query = ParseQuery.getQuery("GameScore");
query.whereEqualTo("playerEmail", "dstemkoski@example.com");
query.getFirstInBackground(new GetCallback<ParseObject>() {
  public void done(ParseObject object, ParseException e) {
    if (object == null) {
      Log.d("score", "The getFirst request failed.");
    } else {
      Log.d("score", "Retrieved the object.");
    }
  }
});