Pass string from method to SQLite Database in Android

I'm trying to pass the return of a method into my SQLite Database on the click of a button. The random unique roles should update an already existing column in a table. The trouble is, I have tried calling the method but I am getting errors. I have hit a wall and don't know how I would progress since I am relatively new to programming. This is my code for my activity class:

    public class StartGame extends AppCompatActivity implements    View.OnClickListener {

    DatabaseHelper myDb;
    Button btnRoles;


    public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_startgame);
    myDb = new DatabaseHelper(this);

    btnRoles = (Button)findViewById(R.id.btnAssignRoles);
    assignRoles();

}

public String RandomNumber()  {
    List<String> roles = Arrays.asList("Mafia", "Mafia", "Angel", "Detective", "Civilian", "Civilian", "Civilian");
    Collections.shuffle(roles);
    Random rand = new Random();
    int i = 0;
    while (i < 7) {
        roles.get(i);
        i++;
    }
    return roles.get(i);
}
public void assignRoles() {
    btnRoles.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                     {

                    }
                }
            }
    );

}









@Override
public void onClick(View v) {

}
}

I have this in my database helper class so far for this method:

    public boolean updateRole(String role){
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(COL_ROLE, role);
    db.update(TABLE_NAME, contentValues, "Role =?", new String[] {role});
    return true;
}

My question is, what should I look at to progress this? It's driving me crazy because I can't figure it out and materials online aren't being any help. Any help would be greatly appreciated!