values/array.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string-array name="timer">
        <item>No Time</item>
        <item>10 Seconds</item>
        <item>20 Seconds</item>
        <item>30 Seconds</item>
        <item>40 Seconds</item>
        <item>50 Seconds</item>
        <item>60 Seconds</item>
    </string-array>

</resources>

MainActivity.java

	
public class MainActivity extends AppCompatActivity {

   int selectedTimerItem = 0;
   public static long START_TIME_IN_MILLIS = 60000;
   public static long mTimeLeftInMillis = START_TIME_IN_MILLIS;

 
  @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        ////Shared preference value set on first app start ////
        SharedPreferences prefs = getSharedPreferences("prefs", MODE_PRIVATE);
        boolean firstStart = prefs.getBoolean("firstStart", true);

        if (firstStart) {
            timerDialog();
           // SharedPreferences prefs = getSharedPreferences("prefs", MODE_PRIVATE);
            SharedPreferences.Editor editor = prefs.edit();
            editor.putBoolean("firstStart", false);
            editor.apply();
        }
        
        //////////////////////////////////
        
      
      //Loading variable value from shared preference
        loadData();
        
        //Alert dialog called
        timerDialog();
       
    }
 
 
 public void timerDialog(){

     // Where we track the selected items
    AlertDialog.Builder builder = new AlertDialog.Builder(this);

     // Set the dialog title
     builder.setTitle("Set time for each question")
                // Specify the list array, the items to be selected by default (null for none),
                // and the listener through which to receive callbacks when items are selected
                
    .setSingleChoiceItems(R.array.timer, selectedTimerItem, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {

                        selectedTimerItem = which;


                       switch (selectedTimerItem){
                            case 0:
                                mTimeLeftInMillis = 6000000;
                                break;
                            case 1:
                                mTimeLeftInMillis = 10000;
                                break;
                            case 2:
                                mTimeLeftInMillis = 20000;
                                break;
                            case 3:
                                mTimeLeftInMillis = 30000;
                                break;
                            case 4:
                                mTimeLeftInMillis = 40000;
                                break;
                            case 5:
                                mTimeLeftInMillis = 50000;
                                break;
                            case 6:
                                mTimeLeftInMillis = 60000;
                                break;

                        }


                    }
                })
   .setPositiveButton("Ok", new DialogInterface.OnClickListener() {
    @Override
        public void onClick(DialogInterface dialog, int which) {
        saveData();


        Toast.makeText(SetsActivity.this, "Successfully Saved", Toast.LENGTH_SHORT).show();
        dialog.dismiss();// dismiss the alertbox after chose option

       }
  });

       builder.create().show();

 }
    
    ///////////////////Shared preference support methods for save and load variable values ////////////
    
 public void saveData() {
     SharedPreferences sharedPreferences = getSharedPreferences(SHARED_PREFS, MODE_PRIVATE);
     SharedPreferences.Editor editor = sharedPreferences.edit();
     editor.putInt(TIMER, selectedTimerItem);
     editor.apply();
   
 }
 public void loadData() {
     SharedPreferences sharedPreferences = getSharedPreferences(SHARED_PREFS, MODE_PRIVATE);
     selectedTimerItem = sharedPreferences.getInt(TIMER, 0);
  }

  //////////////////////////////////////////////////////////

        
 }