Resolved #312: Add language switch only if there are multiple languages.

framework/src/Volo.Abp.AspNetCore.Mvc.UI.Theme.Basic/Toolbars/BasicThemeMainTopToolbarContributor.cs

@@ -1,4 +1,8 @@
-using System.Threading.Tasks;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
 using Volo.Abp.AspNetCore.Mvc.UI.Theme.Basic.Themes.Basic.Components.Toolbar.LanguageSwitch;
 using Volo.Abp.AspNetCore.Mvc.UI.Theme.Basic.Themes.Basic.Components.Toolbar.UserMenu;
 using Volo.Abp.AspNetCore.Mvc.UI.Theme.Shared.Toolbars;
@@ -19,7 +23,13 @@ namespace Volo.Abp.AspNetCore.Mvc.UI.Theme.Basic.Toolbars
                 return Task.CompletedTask;
             }
 
-            context.Toolbar.Items.Add(new ToolbarItem(typeof(LanguageSwitchViewComponent)));
+            var requestLocalizationOptions = context.ServiceProvider.GetService<IOptions<RequestLocalizationOptions>>();
+
+            if (requestLocalizationOptions.Value.SupportedCultures.Count > 1)
+            {
+                context.Toolbar.Items.Add(new ToolbarItem(typeof(LanguageSwitchViewComponent)));
+            }
+
             context.Toolbar.Items.Add(new ToolbarItem(typeof(UserMenuViewComponent)));
 
             return Task.CompletedTask;