Save Variables 
public class MainActivity extends AppCompatActivity {

    private Button saveButton;
    private Switch switch1;
    private TextView textView;
   
    public static final String SHARED_PREFS = "sharedPrefs";
    public static final String TIMER = "timer";
    int selectedTimerItem = 0;
     
    
    public static final String SWITCH1 = "switch1";
    private boolean switchOnOff;
  
   

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        saveButton = (Button) findViewById(R.id.save_button);
        switch1 = (Switch) findViewById(R.id.switch1);
        
           saveButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                saveData();
            }
        });


           loadData();
           
        textView.setText(text);
        switch1.setChecked(switchOnOff);
  }
  
  
  public void saveData() {
        SharedPreferences sharedPreferences = getSharedPreferences(SHARED_PREFS, MODE_PRIVATE);
        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.putInt(TIMER, selectedTimerItem);
        editor.putBoolean(SWITCH1, switch1.isChecked());
        editor.apply();
    //    Toast.makeText(this,"set time: "+ mTimeLeftInMillis, Toast.LENGTH_SHORT).show();
    }
    public void loadData() {
        SharedPreferences sharedPreferences = getSharedPreferences(SHARED_PREFS, MODE_PRIVATE);
        selectedTimerItem = sharedPreferences.getInt(TIMER, 0);
        switchOnOff = sharedPreferences.getBoolean(SWITCH1, false);
    }
    
}