How to put value in every items inside spinner with switch case?

im new on java in android studio. I dont know what to do now, i have a spinner “mu”, i put items inside “mu” with AarrayAdapter (makanan_pokok), my question is how can i give a value for every items inside spinner and put it in mapo? thanks…

package stmikbumigoramataram.simulasipemodelan;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.Spinner;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    String[] makanan_pokok = {"...","Nasi Putih 175 kal/200gr","Lontong 38 kal/200gr","Roti Tawar 145 kal/60gr","Bubur 44 kal/200gr"};

    public int mapo,lapak,samur;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        Button tmblhitung = (Button)findViewById(R.id.bhitung);
        Spinner mu = (Spinner)findViewById(R.id.makanan_utama);


        ArrayAdapter Arr_mu = new ArrayAdapter(this,android.R.layout.simple_spinner_item,makanan_pokok);
        Arr_mu.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        mu.setAdapter(Arr_mu);

    }

    public void hitung_kalori(){
        switch (...){
case 1:     
mapo = 0;
case 2:
mapo = 175;
case 3:
mapo = 38;
case 4:
mapo = 145;
        }
    }

}