sharedpreferences : Save to ListView

Question

I have no problem to save list in sharedpreferences and show it in list view but my problem is when i restart the app and try to add items to listview old stored items removed . there is my code:

public void SaveDatesToList(){
    list.add(i+"");
    array = new String[list.size()];
    list.toArray(array);
    tinyDB.putListString("DATES",list);

}

public void getDates(){

    for (String str:tinyDB.getListString("DATES")) {
        list.add(str);
    }

Never store large data in shared preferences , use local storage like SQLite or web storage for this purpose as it will effect apps performance — Abdul Kawee, May 16 '17 at 07:16

score 2 · Answer 1 · answered May 16 '17 at 07:22

Please Try this two function store arrlist and retrive arraylist in sharedprefrence

 private void storeArray() {
    ArrayList<String> arr1 = new ArrayList<>();
    SharedPreferences prefs = this.getSharedPreferences("Demo", Context.MODE_PRIVATE);
    SharedPreferences.Editor edit = prefs.edit();

    arr1.add("A");
    arr1.add("B");
    arr1.add("C");
    arr1.add("D");
    arr1.add("E");

    Set<String> set = new HashSet<String>();
    set.addAll(arr1);
    edit.putStringSet("yourKey", set);
    edit.commit();
}

private void retriveArray() {
    SharedPreferences prefs = this.getSharedPreferences("Demo", Context.MODE_PRIVATE);
    SharedPreferences.Editor edit = prefs.edit();
    Set<String> set = prefs.getStringSet("yourKey", null);
    ArrayList<String> sample = new ArrayList<String>(prefs.getStringSet("yourKey", null));
    Log.d("Check Size", "Check Size" + sample.size());

    if (sample.size() > 0) {
        for (int i = (sample.size() - 1); i >= 0; i--) {
            Log.d("Array Value", "Array Value" + sample.get(i));
        }
    }
}

Same problem when restarting the application and try to save again, Old elements removed and show just the new elements after restarting the app — user2764693, May 16 '17 at 07:27

score 0 · Answer 2 · answered May 16 '17 at 07:37

0

The problem is that you keep overwriting the old data because you probably do not retrieve the old data and append the new data to it.
Retrieve your old data from the SharedPreference and combine them with your new ArrayList. Then store the combined ArrayList.

Example of combining ArrayList<String>

ArrayList<String> first = new ArrayList<String>();
ArrayList<String> second = new ArrayList<String>();      
//Let both arraylists have some data
first.add("data1");   
second.add("data2");   

// now first contains "data1" and "data2"
first.addAll(second);

Now the ArrayList first has all the data. And for example do

editor.putStringSet("KEY", first).apply();

answered May 16 '17 at 07:37

Denny

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my qestion is to add new elements to the old elements in the same array – user2764693 May 16 '17 at 07:59
And that is what I am answering – Denny May 16 '17 at 08:00
its still the same problem old are REMOVED – user2764693 May 16 '17 at 08:06
I don't think you understand your problem by yourself. you have to retrieve the old data, add the new data and save the combined data – Denny May 16 '17 at 08:10
thats true its work fine before Destroying the activity or closing the app. but the problem is when the app closed (destroyed) and restarting it and trying to add to the list – user2764693 May 16 '17 at 08:14
Can't help you more but point in the right direction if you do not show all relevant parts of your code such as what you do restart the app or close the app. The example code works fine for combining arraylists – Denny May 16 '17 at 08:16

sharedpreferences : Save to ListView

2 Answers2