String[] from ArrayList<Class>

Question

I recently started working on an app that does a request to a server and gets a json response.

The "thing" functioned beautifully until i had to implement new stuff in the list and now i have a hard time to fix it.

Any help is very appreciated:

class RemoteConfig
{
// names and type must match what we get from the remote
String[] username;
ArrayList<accDetails> in_groups;
String[] in_groups_sorted;
class accDetails
{
 int group_id;
 String group_label;
 Boolean _is_system;
}

This is just a part of how the class starts, and here is how the json reponse looks like:

{ 
"username":[ 
 "mike"
],
"in_groups":[ 
 { 
 "group_id":2,
 "group_label":"All users",
 "_is_system":true
 },
 { 
 "group_id":4372,
 "group_label":"Privileged User",
 "_is_system":false
 },
 { 
 "group_id":4979,
 "group_label":"Supervisor",
 "_is_system":false
 }
]
}

The problem that i encounter now, is that i have no idea on how to split the in_groups array list and get into String[] in_groups_sorted the value of Group_label if the _is_system value is false.

Any help is highly appreciated.

Thank you, Mike

---

After checking the responses, the cleanest and simplest was the one provided by Abbe:

public String[] groupSettings()
{
 String[] levels = new String[] {};
 if (remoteConfig != null && remoteConfig.in_groups != null){
 for (accDetails ad: remoteConfig.in_groups)
 {
 if (!ad._is_system) {
 levels = ArrayUtils.addAll(levels, ad.group_label); ;
 }
 }
 }
 return levels;
}

• Marco Acierno: You parse the json (using JsonObject/JsonArray and so on) or you let the API build the Object for you?
• Mihai Neacsu: Thank you everyone for your help. I was going to far with my thinking and i forgot to keep it simple. I used part of the code that @Abbe Resina offered and it worked properly. The others were successful as well, but this was the simplest

Answer 1

From your question, I suppose the JSON is already parsed and stored in the in_groups field of RemoteConfig class. And you just need to filter the information you need to populate the in_group_sorted field.

Add the following to the RemoteConfig class:

public initGroupSorted() {
 // Temporary list, since we don't know the size once filtered 
 List<String> labels = new ArrayList<>();
 for (accDetails ad : in_groups) {
 if (ad._is_system) {
 groups.add(ad.group_label);
 }
 }
 in_group_sorted = labels.toArray(new String[labels.size()]);
}

• Mihai Neacsu: Thank you. I modified it for my needs and now it works :) Simple and clean

Answer 2

if you don ́t want to change the way you parse your JSON, you could always do this:

Let accDetails implement Comparable and then use Collections.sort passing in_groups.

if you really want the String[] you could always iterate over in_groups, add to in_groups_sorted and then using Arrays.sort

Answer 3

Mike, let me give you something that should get you going. From your question i got the feeling that your problem was on how to parse the JSON, so before you go write your own parser, consider the following piece of code that i just wrote:

public void createObjects(String rawJSON) {
 try {
 JSONObject object = new JSONObject(rawJSON);
 JSONArray username = object.getJSONArray("username");
 JSONArray inGroups = object.getJSONArray("in_groups");
 RemoteConfig config = new RemoteConfig();
 config.in_groups = new ArrayList<>();
 config.username = username.getString(0);
 for (int i = 0; i < inGroups.length(); i++) {
 JSONObject group = inGroups.getJSONObject(i);
 if (!group.getBoolean("_is_system")) {
 accDetails details = new accDetails();
 details.group_id = group.getInt("group_id");
 details.group_label = group.getString("group_label");
 details._is_system = false;
 config.in_groups.add(details);
 }
 }
 } catch (Exception e) {
 e.printStackTrace();
 }
 }

• Mihai Neacsu: Thank you. I wil test now and let you know how it works.

Answer 4

Here is a Java 8 Solution using Stream's filter,sorted, and map methods:

//ArrayList<accDetails> in_groups is already populated
Stream<accDetails> tempStream= in_groups.stream().filter(p -> p._is_system == false);
tempStream= tempStream.sorted((accDetails o1, accDetails o2) -> o1.group_label.compareTo(o2.group_label));
String[] in_groups_sorted = tempStream.map(s -> s.group_label).toArray(String[]::new);

Separated the calls for visibility, but they can be a one liner:

String[] in_groups_sorted = in_groups.stream().filter(p -> p._is_system == false).sorted((accDetails o1, accDetails o2) -> o1.group_label.compareTo(o2.group_label)).map(s -> s.group_label).toArray(String[]::new);