Shared Preference List View Not Working When App Closed

Im trying to learn how the listview works for an app im creating, I have got the app to show the listview with items, images and a checkbox. Im trying to achieve is: When they cli

Solution 1:

If u want to manage ur product using SharedPreference than u can do like this

MainActivity.java

publicclassMainActivityextendsAppCompatActivity {

ArrayList<Product> products = newArrayList<Product>();
ListAdapter boxAdapter;
private SharedPreferences mPrefs;
private String mData;
publicstaticfinalStringPREFS_NAME="Product_Prefrence";

@OverrideprotectedvoidonCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main2);

    products=getProductArray(this,"Products");
    if(products==null)
    { 
        fillData();
    }
    boxAdapter = newListAdapter(this, products);

    ListViewlvMain= (ListView) findViewById(R.id.lvMain);
    lvMain.setAdapter(boxAdapter);

}

voidfillData() {
    products.add(newProduct("Al", "5230%", R.drawable.ic_launcher, false));
    products.add(newProduct("Al", "5230%", R.drawable.ic_launcher, false));
    products.add(newProduct("Alf", "5230%", R.drawable.ic_launcher, false));
    products.add(newProduct("Alfa", "5230%", R.drawable.ic_launcher, false));
    products.add(newProduct("Alfae", "5120%", R.drawable.ic_launcher, false));
    products.add(newProduct("Alfsdfsdfakher", "50435%", R.drawable.ic_launcher, false));
    products.add(newProduct("Alfasdfsdfkher", "5123120%", R.drawable.ic_launcher, false));
    products.add(newProduct("Alfasdfsdfkher", "501231%", R.drawable.ic_launcher, false));
    products.add(newProduct("Alfaksdfsdfher", "11250%", R.drawable.ic_launcher, false));

}

  @OverridepublicvoidonBackPressed() {
        saveProductArray(MainActivity.this,products,"Products");
        finish();
    }

    publicvoidsaveProductArray(Context c, List<Product> arrayList, String key) {

        SharedPreferencessettings= c.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
        SharedPreferences.Editoreditor= settings.edit();
        Gsongson=newGson();
        Stringjson= gson.toJson(arrayList);
        editor.putString(key, json).apply();

    }

    @NonNullpublic ArrayList<Product> getProductArray(Context c, String key) {

        Gsongson=newGson();
        SharedPreferencessettings= c.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
        Stringjson= settings.getString(key, "");
        Typetype=newTypeToken<ArrayList<Product>>() {
        }.getType();
        ArrayList<Product> arrayList = gson.fromJson(json, type);

        return arrayList;
    }


}

Adapter getView() Method:

@Overridepublic View getView(finalint position, View convertView, ViewGroup parent) {
    Viewview= convertView;
    if (view == null) {
        view = lInflater.inflate(R.layout.item, parent, false);
    }

   finalProductp= getProduct(position);

    ((TextView) view.findViewById(R.id.tvDescr)).setText(p.name);
    ((TextView) view.findViewById(R.id.tvPrice)).setText(p.price + "");
    ((ImageView) view.findViewById(R.id.ivImage)).setImageResource(p.image);

    finalCheckBoxcbBuy= (CheckBox) view.findViewById(R.id.cbBox);

//use click listener instead of checked change
cbBuy.setOnClickListener(newView.OnClickListener()
{
    @OverridepublicvoidonClick(View v)
    {
        if(objects.get(position).isSelected)
       {
              cbBuy.setChecked(false);
              objects.get(position).setSelected(false);

       }
       else
       {
              cbBuy.setChecked(true);
              objects.get(position).setSelected(true);

       }

    }
});


//For scrolling issue use thisif(objects.get(position).isSelected)
       {
              cbBuy.setChecked(true);

       }
       else
       {
              cbBuy.setChecked(false);
       }

            return view;

        }

    }

No need to maintain sharepreference for single product value.

Hope this will help u..if u still face problem we will find other way