Adding the value of a text field and a saved value from SharedPreferences to an array

Question

I have a text field and I want its value to be saved. Also, if the same text field had another value before, it should be saved too.

This is how I tried it:

ArrayList<String> listOfTexts = new ArrayList<>();

SharedPreferences mPrefs = getContext().getSharedPreferences("k-texts", Context.MODE_PRIVATE);
SharedPreferences.Editor prefsEditor = mPrefs.edit();

listOfTexts.add(Objects.requireNonNull(_customTextField.getText()).toString());
listOfTexts.add(mPrefs.getString("k-text", ""));

Gson gson = new Gson();
String json = gson.toJson(listOfTexts);
prefsEditor.putString("k-text", json);
prefsEditor.apply();

I have saved multiple values in that field. The values are: a, b, c and d

Well, in that case, json returns ["d","["c","[\"a\",\"\",\"b\",\"[\\\"a\\\",\\\"\\\"]\"]"]"] but what I want is ["a", "b", "c", "d"]

How can I get the result that I want?

Answer 1

in this case exits some conflicts in your logic . Instead using Gson use String.format .

When you are adding a in your arraylist and saving to shared preference its giving perfect result [a] .

Then you are trying to add b from edittext and [a] got from preference - result [b,[a]]. and when you trying to make it json its making too conflict .

However , based on your requirement the result should be ["a", "b", "c", "d"]

1. So when retrieve data from preference replace [] . After replaced it looks like "a" or "a", "b" or etc . We dont need [] from preference , we would get it from ArrayList .

   valuefromPrefrence = mPrefs.getString("k-text", null);
   try {
       finalpreferenceValue = valuefromPrefrence.replace("[", "").replace("]",    "");
   } catch (Exception e) {
    e.printStackTrace();
   }
   

2. We can check saved data to skip duplicate data store .

   if (finalpreferenceValue != null && finalpreferenceValue.contains(valueofeditText)) {
            Toast.makeText(getApplicationContext(), "Data already exists", Toast.LENGTH_SHORT).show();
        } else {
   

3. Then format the string as our requirement before add the string to arraylist .

   String allvalues = String.format("" + "%s," + "\"" + "%s\"", finalpreferenceValue, valueofeditText);
   

4. Then add formated String and store the data . Thats it .

So you may check -

        ArrayList<String> listOfTexts = new ArrayList<>();

    SharedPreferences mPrefs = getApplicationContext().getSharedPreferences("k-texts", Context.MODE_PRIVATE);
    SharedPreferences.Editor prefsEditor = mPrefs.edit();


    String valueofeditText = Objects.requireNonNull(_customTextField.getText()).toString();
    String valuefromPrefrence, finalpreferenceValue = null;

    valuefromPrefrence = mPrefs.getString("k-text", null);
    try {
        finalpreferenceValue = valuefromPrefrence.replace("[", "").replace("]", "");
    } catch (Exception e) {
        e.printStackTrace();
    }
    if (finalpreferenceValue != null && finalpreferenceValue.contains(valueofeditText)) {
        Toast.makeText(getApplicationContext(), "Data already exists", Toast.LENGTH_SHORT).show();
    } else {

        String allvalues = String.format("" + "%s," + "\"" + "%s\"", finalpreferenceValue, valueofeditText);

        //replace null, got from first time load   valuefromPrefrence = mPrefs.getString("k-text", "");

        String rallvalues = allvalues.replace("null,", "");

        listOfTexts.add(rallvalues);

        prefsEditor.putString("k-text", String.valueOf(listOfTexts));
        prefsEditor.apply();
    }