![A simple list
• ListView
– Contains a list
– android:id=“@android:id/list”
• Elements of the list
– android.R.layout.simple_list_item_1
• Static
– May use String[]
• Dynamic
– Use ArrayList<String>
20](https://image.slidesharecdn.com/mdad4-201112121014/85/MDAD-5-Android-Lists-adapters-and-recycling-20-320.jpg)
MDAD 5 - Android - Lists, adapters and recycling
- 1. Android Lists, adapters and recycling
- 2. Bibliography 1. Wallace Jackson, Android Apps for Absolute Beginners, Apress, 2017 2. Hello Views, http://developer.android.com/guide/tutorials/vi ews/index.html 3. Android Application Fundamentals, http://developer.android.com/guide/topics/fun damentals.html 2
- 3. Contents • MVC • Lists – Model – Adaptor • List Elements – Simple – from XML • ListActvity • Optimization – Recycling – Tags – Cache • GridView 3
- 4. Model View Controller • Pattern • Splits – UI – Program – Data storage • Advantages – Programing with components – Easier to maintain • Disadvantages – May be slow 4
- 5. MVC Empirical Database (Model) Display (View) Program logic (Controller) 5
- 7. Observer 7
- 8. Observator • Pattern • Splits – Observed object – Observer • Advantages – Programming with components – Easier to maintain – Standard way • Disadvantages – May be slow 8
- 9. Gmail - Notification New email 9
- 10. Specific Activities • ListActivity – Specially for a list – May have other components – List ID • android:id=“@android:id/list” • Special functions – onListItemClick (…) – setListAdapter (…) 10
- 12. Adapter 12
- 13. ListView • A vertical container – Similar with ScrollView – Optimized for movement • Identical components – Each row – Almost true ;) • Adapter’s role – Creates these components • Events – setOnItemClickListener (…) – setOnItemLongClickListener (…) 13
- 14. Adapter • Part of View • Specifies the way of display – Adapts the data – Modifies the View 14
- 15. ListView Adapter • Predefined – ArrayAdapter • User defined – Implementation of ListAdapter – Extend BaseAdapter 15
- 16. Usage of ArrayAdapter (XML) • Example – Static list 16
- 17. Usage of ArrayAdapter (Java) • Example – Static List 17
- 18. Usage of ArrayAdapter (XML) • Example – Dynamic List 18
- 19. Usage of ArrayAdapter (Java) 19
- 20. A simple list • ListView – Contains a list – android:id=“@android:id/list” • Elements of the list – android.R.layout.simple_list_item_1 • Static – May use String[] • Dynamic – Use ArrayList<String> 20
- 21. The List with complex elements • Elements – Components • EditView • ImageView • Container • Adapter custom-made – Implement ListAdapter – Extend BaseAdapter 21
- 22. Extend BaseAdapter • View getView (int position, View convertView, ViewGroup list) • int getCount () • Object getItem (int position) • long getItemId (int position) • int getViewTypeCount () • int getItemViewType (int position) 22
- 28. Recycling • Objects reusage • Avoid object creation – new is bad for memory! • Use – Buffers – Lists 28
- 31. Different types of elements? int getViewTypeCount () int getItemViewType (int position) 31
- 33. Tags (for View) • void setTag (Object tag) • Object getTag () 33
- 34. Efficient using Tag Utilizarea tag-ului 34
- 35. GridView • Identical with ListView – Extend BaseAdapater 35
- 36. The new RecyclerView • A new way of building lists – Uses several layouts • Not just a LinearLayout – The developer has to use recycling and tagging • Extend RecyclerView.Adapter – onCreateViewHolder() • Inflate the view – onBindViewHolder() • Set the View’s data – getItemCount() 36
- 37. Conclusions • Lists – Linear containers – Contain components • Including containers • ListActivity – Activity with special functions for list • Adapter – Formats the data from the model for the list – Simple – Custom made – Recycling of elements • Elements – Described in XML 37
- 38. Keywords • MVC • Adaptor • Classes – ListActivity – ListView – GridView – View – ArrayAdapter – BaseAdapter – ArrayList • Interfaces – ListAdapter • Recycling • Tags 38
- 39. Questions 39