Android: Save JSON data into SharedPreferences

I have this ListView which fetches its data (image+text) from JSON on the web. Now I have a task to make the ListView is accessible without internet connection. My idea is by saving the JSON data from the web when the app is run for the first time with internet, and when it can't find internet connection it will get the data from the persistent Storage.

Can anybody help me with this? I'm still a beginner can't find the example of SharedPreferences with JSON. Thanks a lot

public class ProjectsList extends Activity {
    /** Called when the activity is first created. */
    //ListView that will hold our items references back to main.xml
    ListView lstTest;

    //Array Adapter that will hold our ArrayList and display the items on the ListView
    ProjectAdapter arrayAdapter;


    //List that will  host our items and allow us to modify that array adapter
    ArrayList<Project> prjcts=null;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.projects_list);

        //Initialize ListView
        lstTest= (ListView)findViewById(R.id.lstText);

         //Initialize our ArrayList
        prjcts = new ArrayList<Project>();
        //Initialize our array adapter notice how it references the listitems.xml layout

        arrayAdapter = new ProjectAdapter(ProjectsList.this, R.layout.listitems,prjcts,ProjectsList.this);

        //Set the above adapter as the adapter of choice for our list
        //lstTest.setAdapter(arrayAdapter);



            lstTest.setAdapter(arrayAdapter);
            if (isOnline())
            {
        //Instantiate the Web Service Class with he URL of the web service not that you must pass
        WebService webService = new WebService("http://liebenwald.spendino.net/admanager/dev/android/projects.json");


        //Pass the parameters if needed , if not then pass dummy one as follows
        Map<String, String> params = new HashMap<String, String>();
        params.put("var", "");

        //Get JSON response from server the "" are where the method name would normally go if needed example
        // webService.webGet("getMoreAllerts", params);
        String response = webService.webGet("", params);

        try
        {
            //Parse Response into our object
            Type collectionType = new TypeToken<ArrayList<Project>>(){}.getType();

            //JSON expects an list so can't use our ArrayList from the lstart
            List<Project> lst= new Gson().fromJson(response, collectionType);


            //Now that we have that list lets add it to the ArrayList which will hold our items.
            for(Project l : lst)
            {
                prjcts.add(l);
                ConstantData.projectsList.add(l);
            }

            //Since we've modified the arrayList we now need to notify the adapter that
            //its data has changed so that it updates the UI
            arrayAdap开发者_StackOverflow社区ter.notifyDataSetChanged();
        }
        catch(Exception e)
        {
            Log.d("Error: ", e.getMessage());
        }
       }

        lstTest.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {              
                Intent care = new Intent(ProjectsList.this, ProjectDetail.class);
                care.putExtra("spendino.de.ProjectDetail.position",position);
                startActivity(care);
            }
        });




    }
    @Override
    public void onDestroy()
    {
        yAdapter.imageLoader.stopThread();
        lstTest.setAdapter(null);
        super.onDestroy();
    }

    protected boolean isOnline() {
        ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo netInfo = cm.getActiveNetworkInfo();
        if (netInfo != null && netInfo.isConnected()) {
            return true;
        } else {
             AlertDialog.Builder alertbox = new AlertDialog.Builder(this);
             alertbox.setTitle("spendino Helfomat");
             alertbox.setMessage ("Please check your internet connection");
             alertbox.setPositiveButton("OK", new DialogInterface.OnClickListener() {
                 public void onClick(DialogInterface dialog, int id) {
                      //Main.this.finish();
                 }
             });
             alertbox.show();
            return false;
        }
    }


}

SharedPreferences has no methods for saving a JSON object as is, you must try to convert it to a String. Then when getting it you must parse this String back to JSON. Good luck!

JSON to String:

JSONObject o = new JSONObject(data.trim());
                String name = o.getString(Constants.NAME);
                long date = o.getLong(Constants.DATE);
                String mes = o.getString(Constants.MESSAGE);

                StringBuilder buf = new StringBuilder(text.getText());

                buf.append(name).append(" (").append(dfTime.format(new Date(date))).append(")\n").append(mes).append("\n");

                text.setText(buf.toString());

Making a JSON from a String is not a harder task, use StringTokenizer. Good luck!