How would I save an Integer array list to shared preferences

Question

I've been trying to save an integer array list in shared preferences for a couple of days now but cannot figure out how to do it.

here's the array list i'm trying to save

        ////list that contains checked routes///
        ArrayList<Integer> checkedRoutePosition = new ArrayList<>();

and here's how the array obtains the values within it

       int listViewItemPosition = ((Activity) getContext()).getIntent().getIntExtra("listViewItemPosition",0);

       checkedRoutePosition.add(listViewItemPosition);

In another activity after you click the back button a new intent is started that takes me to this activity. The intent passes in the listViewItemPosition value that I need to save to the array.

The above lines of code are in my getView method of my custom adapter for a listview. After saving them I want to compare them to position in my getView. Where the values are equal I want to set a certain image. Is this code the right way to do that?

  for(int i=0; i<checkedRoutePosition.size(); i++)
                if(position == checkedRoutePosition.get(i)) {
                    checkImageView.setImageResource(checkImageResourceId);
                }

Thanks for any help!

Gabe Sechan · Accepted Answer · 2016-12-11 01:20:29Z

2

You can't write any arrays or arraylists to shared preferences. The closest you can do is write the integers to a comma separated string, write the string, and parse it when you need to read it. This is only appropriate if the size of the array is relatively small. If its large, you need to move away from SharedPreferences to another form of storage such as a file or database.

answered Dec 11, 2016 at 1:20

Gabe Sechan

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3 Comments

zsh5032 Over a year ago

It will have about 180 values in it. Is that too large?

Gabe Sechan Over a year ago

THe main effect of it being too large will be it being slow to parse and slow to read/write the shared preference, especially if there's other data in the same preference file. So too big is mainly determined by performance.

Karun Shrestha Over a year ago

Using a sql database would be a better solution

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