5.1 What Is Fragment?
5.2 How to Use Fragment
5.2.1 Basic Use of Fragment
5.2.2 Add Fragment Dynamically
5.2.3 Back Stack for Fragment
5.2.4 Interaction Between Fragment and Activity
5.3 Lifecycle of Fragment
5.3.1 Fragment State and Callbacks
5.3.2 Experiment with Fragment Lifecycle
5.4 Dynamically Load Layout
5.4.1 Use Qualifier
5.4.2 Use Smallest-Width Qualifier
5.5 Fragment Best Practice: A Basic News App
5.6 Kotlin Class: Extension Function and Operator Overloading
5.6.1 Extension Function
5.6.2 Operator Overloading
5.7 Summary and Comment