Tukukkk

I only have 2 activities which are Main and second activities however sharedpreference works between 2 activities but when I restarted it it never goes to the if statement(Main activity) if(prefs != null) which means prefs is always null when I restart it. Does sharedpreference actually saves data when the application is closed? Thx in advance :)

MainActivity



package com.example.hongsukchoi.rentaltruck;



import android.content.Intent;

import android.provider.MediaStore;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.util.Log;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

import android.widget.RadioButton;

import android.widget.RadioGroup;

import android.content.SharedPreferences;



import java.util.ArrayList;

import java.util.HashSet;

import java.util.Set;





public class MainActivity extends AppCompatActivity {



    private EditText mile_edittext;

    private RadioGroup radio;

    private Button submit_button;

    double truck_price;

    double mile_price;

    double total_price;

    private int truck_type;

    private RadioButton ten;

    private RadioButton seventeen;

    private RadioButton twentysix;





    SharedPreferences prefs;

    SharedPreferences.Editor editor;



    Set<String> mySet = new HashSet<>();





    @Override

    protected void onCreate(Bundle savedInstanceState) {



        ten = (RadioButton) findViewById(R.id.tenfeettruck);

        seventeen = (RadioButton) findViewById(R.id.seventeenfeettruck);

        twentysix = (RadioButton) findViewById(R.id.twentysixfeettruck);





        //ten.setChecked(true);



        if(prefs != null) {

            System.out.println("This is what I am looking for " + prefs.getAll());

            //R.id.checked

            ten.setChecked(true);





        }

        System.out.println("Application is now started");



        //ArrayList<String> allPrefs = new ArrayList(prefs.getStringSet("total_set", null));

       // System.out.println("HERE ARE ALL THE PREFERENCES(Main acivity): " + allPrefs.toString());











        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);



        prefs = getSharedPreferences("type", MODE_PRIVATE);

        editor = prefs.edit();



        radio = (RadioGroup) findViewById(R.id.truckRadio);

        submit_button = (Button) findViewById(R.id.submit_button);

        mile_edittext = (EditText) findViewById(R.id.mile_edittext);







        submit_button.setOnClickListener(new View.OnClickListener(){





            @Override

            public void onClick(View v) {



                String temp3 = mile_edittext.getText().toString();

                mile_price = Double.parseDouble(temp3);









                total_price = truck_price + (mile_price*2);





                String total2 = String.valueOf(total_price);



                //editor.putString("total", total2);

                //editor.putStringSet("total_set", mySet);

                editor.putInt("type", truck_type);

                editor.commit();







                Intent i = new Intent(MainActivity.this, SecondActivity.class);

                i.putExtra("total",total2);

                //i.putExtra("type", truck_type);

                startActivity(i);















            }

        });

















    }

    public void onRadioButtonClicked(View view) {

        // Is the button now checked?

        boolean checked = ((RadioButton) view).isChecked();



        // Check which radio button was clicked

        switch(view.getId()) {

            case R.id.tenfeettruck:

                if (checked)

                    truck_price = 19.99;

                truck_type = 10;



                mySet.add(String.valueOf(truck_type));







                break;

            case R.id.seventeenfeettruck:

                if (checked)

                    truck_price = 29.99;

                truck_type = 17;





                mySet.add(String.valueOf(truck_type));





                break;

            case R.id.twentysixfeettruck:

                if (checked)

                    truck_price = 39.99;

                truck_type = 26;





                mySet.add(String.valueOf(truck_type));





                break;

        }

    }









}





SecondActivity



package com.example.hongsukchoi.rentaltruck;



import android.app.Activity;

import android.content.Intent;

import android.content.SharedPreferences;

import android.os.Bundle;

import android.widget.ImageView;

import android.widget.TextView;



import org.w3c.dom.Text;



import java.util.ArrayList;



public class SecondActivity extends Activity {

    private double total_price;

    private ImageView myImgView;

    private TextView Total_displaying;

    private TextView whichtruck;

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_second);



        myImgView = (ImageView)findViewById(R.id.truckimage);

        whichtruck = (TextView)findViewById(R.id.whichtruck);

        SharedPreferences prefs = getSharedPreferences("type", MODE_PRIVATE);



        SharedPreferences prefs_set = getSharedPreferences("total_set", MODE_PRIVATE);



        if(prefs.getStringSet("total_set", null) != null) {



            ArrayList<String> allPrefs = new ArrayList(prefs.getStringSet("total_set", null));

            System.out.println("HERE ARE ALL THE PREFERENCES(Second acivity): " + allPrefs.toString());

        }



        //SharedPreferences type = getSharedPreferences("type", MODE_PRIVATE);

        Intent i = getIntent();

        String temp = i.getExtras().getString("total");



        int type_temp = prefs.getInt("type", 0);





        if(temp != null) {

             total_price = Double.parseDouble(temp);

        }







        if(type_temp == 10)

        {

            myImgView.setImageDrawable(getResources().getDrawable(R.drawable.truckten));

            whichtruck.setText("is 10 feet truck!");



        }

        else if(type_temp == 17)

        {

            myImgView.setImageDrawable(getResources().getDrawable(R.drawable.truckseventeen));

            whichtruck.setText("is 17 feet truck!");



        }

        else if(type_temp == 26)

        {

            myImgView.setImageDrawable(getResources().getDrawable(R.drawable.trucktwentysix));

            whichtruck.setText("is 26 feet truck!");



        }



        Total_displaying = (TextView) findViewById(R.id.Total_displaying);

        String display = Double.toString(total_price);

        Total_displaying.setText(display);

    }





}

sharedpreference do save data when the application is closed.

You are checking if "prefs" is not null before initiate it.

Try the code below and check if this solves your problem :

inside onCreate:

   prefs = getSharedPreferences("type", MODE_PRIVATE);

inside onStart:

   if(prefs != null) {

        System.out.println("This is what I am looking for " + prefs.getAll());

        //R.id.checked

        ten.setChecked(true);

    }