Finally, we need to make the SettingsActivity available from the MainActivity. As we said before, we will use the options menu on the MainActivty for this.

First of all, let's create a menu.xml file under the app/src/main/res/menu directory. The structure of the menu will be set to the following:

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/settings"
        android:icon="@drawable/ic_settings_black"
        android:title="Settings" />
</menu>

This means that there will be just a single menu entry named settings. Also, we have added an icon for the entry:

@drawable/ic_settings_black

Usually, icons can be generated using Android Studio with File||New||Image Asset. This can be seen here:

Next, we will enable this menu in the MainActivity by adding menu initialization code in the MainActivity class:

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.menu, menu);
    return true;
}

The last step is to handle the action when the menu option gets selected by having the following in the MainActivity:

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case R.id.settings:
            startActivity(new Intent(this, SettingsActivity.class));
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}

That's it; now we have a fully working SettingsActivity class. After the settings option is clicked on, the user should be presented with this screen:

When a user clicks on Symbols or Keywords entries, a dialog box will be shown where the Keywords or Symbols can be entered:

The values here are separated by spaces.