How to get data from the db in activity a, when activity b is closed in Android with ActiveAndroid

im new to this and have some problems, thanks for your help.

Situation: I have a MainActivity and a second Activity called MainAddMedActivity. I get data from the second activity through an EditText and save it in the database. My intention is to display the data from the EditText in a ListView in the MainActivity by taking it from the database. How to do it the right way ?

Med:

@Table(name = "Med")
public class Med extends Model {
// Zähler für eindeutige IDs
private static long counter = 0;

@Column(name = "_id", unique = true, onUniqueConflict = Column.ConflictAction.REPLACE)
public long id;

@Column(name = "Description", index = true)
public String description;

public Med() {
    super();
}

public Med(String message) {
    super();
    id = counter++;
    description = message;
}
}

MedDAO:

public class MedDAO {

public static List<Med> getAll(String text) {
    return new Select()
            .from(Med.class)
            .where("Description like ?", new String[]{'%' + text + '%'})
            .orderBy("Description")
            .limit(40)
            .execute();
}

public static List<Med> getAll() {
    return new Select()
            .all()
            .from(Med.class)
            .execute();
}

public static List<Med> getOneItem(String text) {
    return new Select()
            .from(Med.class)
            .where("Description = ?", text)
            .execute();
}

public static void insertMed(String msg){
    new Med(msg).save();
}

public static void remove(String text) {
    new Delete().from(Med.class).where("Description = ?", text).execute();
}
}

MainActivity:

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {
private ArrayAdapter<String> listAdapter;

@Override

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            Intent intent = new Intent(view.getContext(), MainAddMedActivity.class);
            startActivity(intent);
        }
    });

    ListView mainListView = (ListView) findViewById(R.id.listView);

    mainListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            String item = listAdapter.getItem(position);
            //Aus DB entfernen
            MedDAO.remove(item);
            //Aus Liste im Gui entfernen
            listAdapter.remove(item);
            Toast.makeText(getBaseContext(), item + "gelöscht", Toast.LENGTH_SHORT).show();
        }
    });
    //TODO: ArrayAdapter bugt
    //Adapter für die Liste erzeugen
    listAdapter = new ArrayAdapter<String>(this, R.layout.single_row, R.id.listMedNrPart);
    mainListView.setAdapter(listAdapter);


@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public void onStart() {
    super.onStart();
}

@Override
public void onStop() {
    super.onStop();
}


@Override
public void onResume() {
    super.onResume();
//        MedDAO.getLatestItem();
    /*int max = listAdapter.getCount();
    int i = 0;
    while (i < max){
        Log.d("MainActivity", listAdapter.getItem(i));
        i++;
    }*/
//        listAdapter.add(MedDAO.getLatestItem().toString());
}
}

MainAddMedActivity:

public class MainAddMedActivity extends AppCompatActivity {


private EditText txtSearchMedicament;
private EditText txtNumberMedicament;
private TextView txtAlarmPrompt;
private TimePickerDialog timePickerDialog;
private Switch switchReminder;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_add_med);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);


    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            EditText description = (EditText) findViewById(R.id.txtSearchMedicament);
            String text = description.getText().toString();
            **//SAVE IN DATABASE**
            MedDAO.insertMed(text);
            //TODO: Close Activity
        }
    });

    getSupportActionBar().setDisplayHomeAsUpEnabled(true);

    this.txtSearchMedicament = (EditText) findViewById(R.id.txtSearchMedicament);
    this.txtNumberMedicament = (EditText) findViewById(R.id.txtNumberMedicament);
    this.txtAlarmPrompt = (TextView) findViewById(R.id.txtAlarmPrompt);
    this.switchReminder = (Switch) findViewById(R.id.switchReminder);


    switchReminder.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
            if (isChecked) {
                cancelSwitch();
            }
        }
    });