Should I put same action button in both Action Bar and screen content?

1. How to set button in action bar in android?
2. How to add action bar icon in android studio?
3. What is action bar?

How to set button in action bar in android?

Add Action Buttons

To add actions to the action bar, create a new XML file in your project's res/menu/ directory. The app:showAsAction attribute specifies whether the action should be shown as a button on the app bar.

How to add action bar icon in android studio?

To generate ActionBar icons, be sure to use the Asset Studio in Android Studio. To create a new Android icon set, right click on a res/drawable folder and invoke New -> Image Asset.

What is action bar?

The app bar, also known as the action bar, is one of the most important design elements in your app's activities, because it provides a visual structure and interactive elements that are familiar to users.