A class I wrote to save an ArrayList<String> to a single String to be saved in Android's SharedPreferences.

ArrayHelper.java

package com.example;
// Change the package name to match your package

import java.util.ArrayList;

import org.json.JSONArray;
import org.json.JSONException;

import android.content.Context;
import android.content.SharedPreferences;
import android.preference.PreferenceManager;

public class ArrayHelper {
  Context context;
	SharedPreferences prefs;
	SharedPreferences.Editor editor;
	
	public ArrayHelper(Context context) {
		this.context = context;
		prefs = PreferenceManager.getDefaultSharedPreferences(context);
		editor = prefs.edit();
	}
	
	/**
	 * Converts the provided ArrayList<String>
	 * into a JSONArray and saves it as a single
	 * string in the apps shared preferences
	 * @param String key Preference key for SharedPreferences
	 * @param array ArrayList<String> containing the list items
	 */
	public void saveArray(String key, ArrayList<String> array) {
		JSONArray jArray = new JSONArray(array);
		editor.remove(key);
		editor.putString(key, jArray.toString());
		editor.commit();
	}
	
	/**
	 * Loads a JSONArray from shared preferences
	 * and converts it to an ArrayList<String>
	 * @param String key Preference key for SharedPreferences
	 * @return ArrayList<String> containing the saved values from the JSONArray
	 */
	public ArrayList<String> getArray(String key) {
		ArrayList<String> array = new ArrayList<String>();
		String jArrayString = prefs.getString(key, "NOPREFSAVED");
		if (jArrayString.matches("NOPREFSAVED")) return getDefaultArray();
		else {
			try {
				JSONArray jArray = new JSONArray(jArrayString);
				for (int i = 0; i < jArray.length(); i++) {
					array.add(jArray.getString(i));
				}
				return array;
			} catch (JSONException e) {
				return getDefaultArray();
			}
		}	
	}
	
	// Get a default array in the event that there is no array
	// saved or a JSONException occurred
	private ArrayList<String> getDefaultArray() {
		ArrayList<String> array = new ArrayList<String>();
		array.add("Example 1");
		array.add("Example 2");
		array.add("Example 3");
		
		return array;
	}
}

I have a question about implementing this code into a program. What is the String key that is supposed to be passed into the saveArray and getArray functions? Is it the name of the SharedPreference that is being saved?

When I implemented this class into my code, I could get the ArrayList to save onPause and OnStop, but not onDestroy as if the ArrayList wasn't being saved.