You now need to add some icons to the toolbar you added in the previous lesson. There's also a thing called the Overflow Menu. This is for items that won't fit on the toolbar. You'll then typically see three dots. Press the dots and you see a sub menu appear. This sub menu is the Overflow Menu. Let's see how to do that.
Items that go on your toolbars come from a separate XML file that is placed in a menu folder. You then attach the XML file to your toolbar using Java code.
First, we'll need the menu folder.
In the Explorer area on the left of Android Studio, right-click the res folder. From the menu that appears, select New > Android resource directory:
When you get the dialogue box up, select menu from the Resources type dropdown:
The Directory name box at the top will then change to menu:
Click OK to create a menu folder inside of your res directory:
Now right click your new menu folder. From the menu that appears, select New > Menu resource file:
When you get the New Resource File dialogue box up, type menu_items as the file name:
Click OK to create a new XML file in your menu folder:
The XML file will open up in Design view in your main coding area. It should look something like this: (Later versions of Android Studio will have a Cast Button item at the top.)
Have a look on the left, though, and notice the Palette and the Component Tree. You can drag items from the Palette onto either your Component Tree or directly onto your toolbar.
Drag a Menu Item from the Palette to your Component Tree or toolbar:
Your Component Tree will then look like this:
And your layout will look like this:
Notice that the layout is showing the three dots for the Overflow Menu, and a menu item with the default name of item.
With your new menu item selected, have a look at the properties area on the right:
We'll need IDs for the menu items. Type favourites_page as the ID. For the title, click the Pick a Resource button to the right of the title area. Then select the favourites string resource you set up in the previous lesson:
Click OK and your layout will update with your new title:
The title will appear only if a menu item is pushed to the Overflow Menu. It is pushed to the Overflow Menu if there is not enough room on the toolbar. But only if you have specified this in the showAsAction property. Click inside of this property to see the following box appear in earlier versions of Android Studio:
In later versions, you need to click the little flag. You'll then see the same dialog box but in a different design:
Select the one for ifRoom. This means that the item will appear on the toolbar if there is room for it, otherwise it will get pushed to the Overflow Menu. The never means that it will never appear on the toolbar but always on the Overflow Menu; always means it will always appear on the toolbar; withText means that the title you add will always be displayed. (The collpaseActionView item is used with something called an Action Layout. We won't be using these.)
Your properties area should look like this, so far:
You'll probably want an icon to appear for your toolbar items. Instead of designing one yourself, there are lots of inbuilt ones you can use. You add these to the drawable folder as a Vector asset. You'll learn how to do that in the next lesson below.