Develop Reference

Looping out JSON Array using ArrayList

I am trying to learn retrofit and I have made successful attempts at posting data and now I am trying to retrieve JSON array which looks as follows:
{
"result": "success",
"message": "All Questions Have Been Selected",
"question": {
"all_question_ids": ["1","2","3"]
}
}
I am using the following getter
public ArrayList getAll_question_ids(){
return all_question_ids;
}
I am retrieving using Retrofit as follows
if (resp.getResult().equals(Constants.SUCCESS)) {
SharedPreferences.Editor editor = pref.edit();
Log.d("Question_IDs", "getAllQuestionID() = " + response.body().getQuestion().getAll_question_ids() );
editor.putString(Constants.All_QUESTION_IDS,((resp.getQuestion().getAll_question_ids().toString())));
editor.apply();
}
progress.setVisibility(View.INVISIBLE);
It is here that I am stuck, as I am retrieving the array ok but I am unsure how to loop out the Array which is now stored in Shared Preferences.
When I place a toast to show me how the IDs are coming across, my toast confirms the data as [1,2,3]
The goal is to add a dynamic button and the individual ID, i.e button 1, button 2 etc every-time the loop is iterated.
I have tried the following:
String questionNumber = pref.getString(Constants.All_QUESTION_IDS, "");
for (int i =0; i < questionNumber.length(); i++) {
try {
/*Dynamically create new Button which includes the question name
*/
AppCompatButton btn_question = new AppCompatButton(getActivity());
/*LayoutParams (int width, int height,float weight)
As LayoutParams is defaulted in px, I have called a method called dpToPX to make sure
the dynamically added EditText is the same size on all devices.
*/
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(dpToPx(280), dpToPx(45), 1);
btn_question.setBackgroundColor(Color.parseColor("#3B5998"));
btn_question.setTextColor(Color.WHITE);
// btn_question.setText(String.valueOf(x));
btn_question.setText("Question "+ pref.getString(Constants.All_QUESTION_IDS,""));
btn_question.setGravity(Gravity.CENTER);
//generate unique ID for each new EditText dynamically created
View.generateViewId();
//Log.d("TEST VALUE", "Question1 generated ID = " + btn_question.generateViewId());
params.setMargins(0, dpToPx(10), 0, dpToPx(10));
btn_question.setPadding(0, 0, 0, 0);
btn_question.setLayoutParams(params);
allEds.add(btn_question);
mLayout.addView(btn_question);
} catch (Exception e) {
Log.d(TAG, "Failed to create new edit text");
}
}
However the above is adding the value as it appears in the array e.g [1,2,3] which is obviously not what I want.
I have added a photo in case my explanation isn't clear. I want a button with 1 number added to it each time the loop iterates but I am unable to figure this out.
I have looked through lots of resource but cannot find an answer that is relevant to my problem, although, if there is, I am not familiar enough to recognise a similar issue.
If someone can offer some assistance, I would appreciate it!

When you call editor.putString(Constants.All_QUESTION_IDS,((SOMETHING.toString())));, what is actually stored depends on the implementation of the toString method in the type of SOMETHING (in this case String[]). So avoid doing that. Instead, since you're already using Gson or Jackson (or others), store the question_idsas JSON:
final String jsonIds = gson.toJson (resp.getQuestion().getAll_question_ids());
editor.putString(Constants.All_QUESTION_IDS, jsonIds);
Your actual stored value no longer depends on the implementation of something that you don't control (String[].toString). It is a valid JSON array and regardless of what tool/library you use to read it back, it's valid.
Now, to read back the stored data:
final String storedJson = pref.getString(Constants.All_QUESTION_IDS, null);
if (null == storedJson) {
// TODO: No question ids found
}
final String[] ids = gson.fromJson (storedJson, String[].class);
for (int i = 0; i < ids.length; i++) {
// make your buttons
}

This is a problem of saving and then reading out a List of items (in this case, String instances).
You've chosen to save the list by calling editor.putString() with a value of getAll_question_ids().toString(). That toString() call is going to return a string representation of your list, or, in other words, a String instance with the value [1, 2, 3]. At this point, you no longer have a List proper, but a String that looks like a list.
This is all technically fine, but it means you have to take this into account when you're trying to read out that list.
You've written this to read the list back out:
String questionNumber = pref.getString(Constants.All_QUESTION_IDS, "");
Once this line executes, questionNumber will be a String instance with the value [1, 2, 3]. Again, this is fine, but now we come to the key point: we have to convert this String back into a List.
If you know for sure that the values in this list won't have commas in them, you can do it easily:
Trim the braces off the string using substring()
Create a String[] using split()
Convert your array to a list using Arrays.asList() (you could even skip this step since iterating over an array is just as easy as iterating over a list)
Put that together and you get:
String questionNumber = pref.getString(Constants.All_QUESTION_IDS, "");
questionNumber = questionNumber.substring(1, questionNumber.length() - 1);
String[] array = questionNumber.split(", ");
List list = Arrays.asList(array);
At this point, you can iterate over your array or list:
for (String value : list) {
...
btn_question.setText("Question " + value);
...
}

Convert Array list to Sparse Array

I have copied some code from a project and want to reuse a small part of it in my private app.
The class contains a Sparse Array
public class GolfResult {
String hcpAfter;
String hcpBefore;
SparseArray roundResults;
public GolfResult() {
hcpAfter = "";
hcpBefore = "";
roundResults = new SparseArray();
}
}
I have created an ArrayList for roundResults that is filled with the necessary data.
Then I am trying to fill the instance with content.
GolfResult golferRes = new GolfResult();
SparseArray<RoundResults> hu= new SparseArray<>();
hu = roundresults; // *
golferRes.setHcpAfter("33");
golferRes.setHcpBefore("kk");
golferRes.setRoundResults(hu);
But the problem is that hu = roudresults is not possible, because of the error message:
required: Android.util.SparseArray found: java.util.Array List
Any help will be welcome.
After receiving two helpful answers I got a step further, but now I am facing the problem that my SparseArray hu is empty {}.
The content of hu should be the class roundresults that has the following structure:
public class RoundResults {
boolean actualRound;
private List<HoleResult> holeResults;
Integer roundId;
Integer roundNumber;
String unfinishedReason;
The arrayList roundresults has the size of 1 and has data in the objects.
unfinishedReason =""
holeResults = ArrayLIST size= 18
roundID = "1"
roundNumber = "1"
actualRound = true
hu ={}
mValues = All elements are null
mSize = 0
Does anybody have an idea why?

SparseArray is different than ArrayList, from the documentation:
SparseArrays map integers to Objects. Unlike a normal array of
Objects, there can be gaps in the indices. It is intended to be more
memory efficient than using a HashMap to map Integers to Objects, both
because it avoids auto-boxing keys and its data structure doesn't rely
on an extra entry object for each mapping.
It's using a key value pair principle where the key is an integer and the value which the key mapping is the object. You need to use put [(int key, E value)](https://developer.android.com/reference/android/util/SparseArray.html#put(int, E)) where the E is your object. Remember that:
Adds a mapping from the specified key to the specified value,
replacing the previous mapping from the specified key if there was
one.
So you need to use a loop to add each object in your ArrayList as #valentino-s says:
SparseArray<RoundResults> hu= new SparseArray<>();
for( int i = 0; i < roundresults.size(); i++) {
// i as the key for the object.
hu.put(i, roundresults.get(i));
}

If I understand well your problem, maybe you can try with this:
for ( int i=0; i<roundresults.size(); i++ ) {
hu.put(i,roundresults.get(i));
}

After some trial and error I found a solution for the empty hu:
Instead of put I used append and it is working now.
hu.append(i, roundresults.get(i));
Time for a beer.

Android: Using a string in place of an object/instance name

I would like to see if I can avoid a lengthy switch or if block by directly converting some strings into an object name. For example, I have a class called Example and I want to [edit] have up to 10 instances of the class Example1, Example2, so on. Can I use something like:
int ExampleNum = 2;
// can be changed to any 1-10 value corresponding to instances
String s = "Example" + String.valueOf(ExampleNum);
Refresh(s);
public void Refresh(Example example){
...
}
Thus I would create a string with the value of Example2 and pass that to my Refresh method.
[edit]
I don't want to use all the instances at once, but rather have other methods that change the int ExampleNum so that when I try to refresh it refreshes the appropriate Example instance.
Rather than saying:
if (ExampleNum == 2)
Refresh(Example2);
I would use the ExampleNum and String to use the right instance name;

Why not use array's instead??
Example[] e = null;
for(int i=1;i<=10;i++)
{
e[i] = new Example();
Refresh(e[i]);
}

Well, your code, as it stands now, doesn't make any sense since you're passing a String to Refresh, which takes an Example object as an argument.
However, if you're asking how you can create the strings Example1, Example2, ... Example 10, you can do this:
for (int i = 1; i <= 10; i++) {
s = "Example" + i;
refresh(s); // assuming this takes a string
}

How to pass ArrayList<Coordinate[]> from one Activity to another

I have tried all day to do this and haven't had any luck. I have an ArrayList with an Array of Coordinate types inside, and I want to pass this from one activity to another. I don't think this is possible through using Intent. So I am wondering what other option do I have? I want something simple..

I'd probably put the values in a database in your first activity and only pass some unique identifier on to the second activity so it can recreate the ArrayList on the other side. But if you want a quick solution, use the intent bundle and serialize/deserialize the coordinates yourself:
ArrayList<Coordinate> mCoords = new ArrayList<Coordinate>();
private void startOtherActivity()
{
int numCoords = mCoords.size();
Intent intent = new Intent();
intent.putExtra("coord_size", numCoords);
for (int i = 0; i < numCoords; i++)
{
Coordinate coord = mCoords.get(i);
intent.putExtra("coord_x_" + i, coord.getX());
intent.putExtra("coord_y_" + i, coord.getY());
}
//start other activity...
}
Then grab the values out of the bundle on the other side and regen the ArrayList.
Edit: Just realized you're talking about Coordinate[]s. Same principle still applies, just nest another for loop in there and keep track of each individual array's length as well.
Update: On the other side, you'd have something like
int len = intent.getIntegerExtra("coord_size", 0);
for(int i = 0; i < len; i++)
{
float x = intent.getFloatExtra("coord_x_" + i, 0.0);
float y = intent.getFloatExtra("coord_y_" + i, 0.0);
mCoords.add(new Coordinate(x, y));
}

You can have a singleton "Model" class, on which you can store the ArrayList object from one activity, and retrieve it from another.

Create Bundle and try to put the ArrayList. Then send the bundle in the intent.

You could write a ParcelableCoordinate class that implements Parcelable, and then have it convert the Coordinate objects into ParcelableCoordinate objects, put them in the intent, and then do the reverse on the other side.

For-loop not working the way i want it to

I have a extremely minor issue that I can't seem to figure out. I'm trying to extract data based on a type of value from an ArrayList> and place it into another ArrayList. The issue is that the for-loop only runs once, which in this case i need it to traverse the entire array and then place the data into the unSuppressedData arraylist.
Below is the for-loop:
for (int x = 0; x < suppressedStatus.length; x++) {
for (int i = 0; i < availData.size(); i++) {
Hashtable<String,String> checkAvail = availData.get(i);
String itemStatus = checkAvail.get("loanStatus");
if (unSuppressedData.contains(checkAvail) == false) {
if (!(itemStatus.equals(suppressedStatus[x]))) {
Log.d("Item Status", itemStatus);
Log.d("Suppressed Status", suppressedStatus[x]);
unSuppressedData.add(checkAvail);
//break;
}
}
}
}
suppressedStatus is a String array
availData is the arraylist i want to extract data from
unSuppressedData is the arraylist i want to place the data in
I believe that it only runs once is due to this line of code:
if (unSuppressedData.contains(checkAvail) == false) {
But i need to this line to check whether my unSuppressdData has the data, if no then will add the data from availData arraylist into unSuppressedData arraylist.
Could it be that i'm writing this piece of code wrongly? Appreciate any insights shed on this.

A good collection type for this sort of thing is the LinkedHashSet. Because it's a set, each element can only be added once. Being a hash, the contains test is quick. Being 'linked' the resulting set is iterated in insertion order.