在单个微调器上添加两个 ArrayList

Question

Refer the image
我想将 favourite_city 的元素与选项匹配，如果找到匹配项，则将 favourite_city 列表设置为选项中最顶端的位置，并包含其自己的内容。

第一个数组列表：

favourite_city=["Hyderabad","Bangalore"]

第二个数组列表：

options=["Nashik","Hyderabad","Mumbai","Bangalore","Chennai","Pune"]

结果：

options=["Hyderabad","Bangalore","Nashik","Hyderabad","Mumbai","Bangalore","Chennai","Pune"]

    DocumentReference docRef5 = FirebaseFirestore.getInstance().collection("admin").document("users_profile").collection("dynamic_profile").document("city");
    docRef5.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
        @Override
        public void onComplete(@NonNull Task<DocumentSnapshot> task) {
            if (task.isSuccessful()) {
                DocumentSnapshot document = task.getResult();
                if (document != null) {

                    //-----------code for loading array item from firebase to spinner view-----------------
                    final List<String> group = (List<String>) document.get("favourite_city");
                    Log.d(TAG, "favourite city list data: " + group);

                    final List<String> group1 = (List<String>) document.get("options");
                    Log.d(TAG, "options list data: " + group1);

                    cityAdapter = new ArrayAdapter<String>(AdminSetting.this, android.R.layout.simple_spinner_item, group1);
                    cityAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
                    citySpinner.setAdapter(cityAdapter);


                    StringBuilder str = new StringBuilder();
                    for (int i = 0; i < group.size(); i++) {
                        if (i >= 0)
                            str = str.append(group.get(i));

                            String searchedItem = str.toString();

                            Log.d(TAG, "result " + searchedItem);

                        int itemPosition = cityAdapter.getPosition(searchedItem);

                        for(int j=0;j<=i;j++) {

                            if (itemPosition == -1) {
                                String message = searchedItem + " : Item not found.";
                                Toast.makeText(getApplicationContext(), message, Toast.LENGTH_SHORT).show();
                            } else {

                                String message = searchedItem + " : Item found and selected.";
                                Toast.makeText(getApplicationContext(), message, Toast.LENGTH_SHORT).show();
                                citySpinner.setSelection(itemPosition);
                            }
                        }

                        Log.d(TAG, "after appending " + str);
                    }
                } else {
                    Log.d(TAG, "No such document");
                }
            } else {
                Log.d(TAG, "get failed with ", task.getException());
            }
        }
    });

Answer 1

首先你的问题不清楚

如果你想合并两个arraylist你需要使用下面的代码

favourite_city.addAll(options) // or Either way

如果你想找到匹配项，你需要像下面那样做

public String getUserId(ArrayList<User> newUsers, ArrayList<User> oldUsers, String email) {

    String userId = null;

    for (User user1 : newUsers) {
        if (user1.email.equals(email)) {
            userId = user1.uid;
            break;
        } 
    }

    if(userId == null){
        for (User user2 : oldUsers) {
            if (user2.email.equals(email)) {
                userId = user2.uid;
                break;
            }
        }
    }

    return userId;
}

Answer 2

为了将收藏的城市放在第一位，您需要知道它们是否包含在城市列表中。

以这段代码为例：

ArrayList<String> favourites = new ArrayList<>(Arrays.asList("city1", "city2"));
ArrayList<String> cities = new ArrayList<>(Arrays.asList("city3", "city4", "city1", "city2"));

for (String favCity : favourites) {
   if (cities.contains(favCity)) {
       cities.add(favourites.indexOf(favCity), favCity);
   }
}

System.out.println(cities);

这将打印以下内容：

[city1, city2, city3, city4, city1, city2]

如果要删除重复的收藏夹城市以仅将它们保留在第一位，则应在将其添加到列表之前添加此行。

cities.remove(favCity);

它会 return:

[city1, city2, city3, city4]

在单个微调器上添加两个 ArrayList

Add two ArrayList on single spinner

android

arraylist

spinner

google-cloud-firestore