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?

you are storing data as json, while you fetch data next time from sharedprefs it will be in json hence you need to convert json string to list of objects and all those objects to `listOfTexts` and then you need to save it in sharedprefs — AgentP, Aug 28 '21 at 14:13
@AgentP thanks, could you please give me an example of that? — xRay, Aug 28 '21 at 18:10
https://stackoverflow.com/questions/44589381/how-to-convert-json-string-into-list-of-java-object check this for idea — AgentP, Aug 28 '21 at 18:18

Zahid Islam · Accepted Answer · 2021-08-29T05:28:16.780

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"]

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();
}

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 {

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

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

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();
    }

Perfect answer! Just what I wanted. Thank you! – xRay Aug 28 '21 at 20:12 — xRay, Aug 28 '21 at 20:12

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

1 Answers1