Order a LIST based on another LIST

Question

I have a class that has a property that is another class. Follow example:

Menu Class

public class Menu implements Serializable {

    private static final long serialVersionUID = 1L;
    private Long id;
    private String descricao;
    private Integer orderVisibilidade;
    private GrupoMenu grupoMenu;
}

Grupomenu class

public class GrupoMenu  implements Serializable {

    private static final long serialVersionUID = 1L;
    private Long id;
    private String descricao;
    private Integer ordemVisibilidade;
}

Well, I have a MENU LIST List<Menu> listMenu.

I created a class to sort through the field ordemVisibilidade class GrupoMenu and it worked.

As I’m making the ordination call:

OrdenaMenuPorGrupoMenu ordenaMenuGrupoMenu = new OrdenaMenuPorGrupoMenu();
Collections.sort(listMenu, ordenaMenuGrupoMenu);

Ordenamenuporgrupomenu

public class OrdenaMenuPorGrupoMenu implements Comparator<Menu> {

    @Override
    public int compare(Menu o1, Menu o2) {
        return o1.getGrupoMenu().getOrdemVisibilidade().compareTo(o2.getGrupoMenu().getOrdemVisibilidade());
    }

}

However, I must order also by the field orderVisibilidade class Menu, I mean, I need to sort the group and then for each group to sort the menus.

If I order by GrupoMenu and then by Menu, he reorders everything just by Menu. How do I make that comparison?

Answer 1

How about you try that?

public class OrdenaMenuPorVisibilidade implements Comparator<Menu> {

    @Override
    public int compare(Menu o1, Menu o2) {
        int d = o1.getGrupoMenu().getOrdemVisibilidade().compareTo(o2.getGrupoMenu().getOrdemVisibilidade());
        if (d != 0) return d;
        return o1.getOrderVisibilidade().compareTo(o2.getOrderVisibilidade());
    }

}

He tries to compare it to the visibility of the group. If you tie (which will happen if both menus are in the same group), then it uses menu visibility to unpack.