RecyclerView

Quick intro talk about the RecyclerView given to Chicago's AndroidListener group on November 19, 2014

Transcript

1. RECYCLERVIEW ANDROID LISTENER NOVEMBER 2014
3. A FLEXIBLE VIEW FOR PROVIDING A LIMITED WINDOW INTO A LARGE DATA SET.
4. Yeah, that's called a LISTVIEW!
5. REDUCES COUPLING
6. DELEGATION
7. MAKES IT EASY TO DO THE RIGHT THING
8. THE 5 CLASSES YOU'LL MEET...
9. ADAPTER
10. 2 ROLES
11. PROVIDING DATA
12. PROVIDING LAYOUTS
13. public VH onCreateViewHolder(ViewGroup parent, int viewType) public void onBindViewHolder(VH holder, int position) public int getItemCount()
14. VIEW HOLDER
15. public final static class ListItemViewHolder extends RecyclerView.ViewHolder { TextView label; TextView dateTime; public ListItemViewHolder(View itemView) { super(itemView); label = (TextView) itemView.findViewById(R.id.txt_label_item); dateTime = (TextView) itemView.findViewById(R.id.txt_date_time); } }
16. LAYOUT MANAGER
17. ATTACHING MEASURING LAYING OUT
18. public class RecyclerView extends ViewGroup { public static abstract class LayoutManager { // The required bits to implement public abstract LayoutParams generateDefaultLayoutParams(); public void scrollToPosition(int position) { if (DEBUG) { Log.e(TAG, "You MUST implement scrollToPosition. It will soon become abstract"); } } public void onLayoutChildren(Recycler recycler, State state) { Log.e(TAG, "You must override onLayoutChildren(Recycler recycler, State state) "); } } }
19. DEFAULT IMPLEMENTATION /** * A {@link android.support.v7.widget.RecyclerView.LayoutManager} implementation which provides * similar functionality to {@link android.widget.ListView}. */ public class LinearLayoutManager extends RecyclerView.LayoutManager { /* REALLY INTERESTING CODE HERE */ }
20. ITEM DECORATION
21. public static abstract class ItemDecoration { /* drawn before the item views */ public void onDraw(Canvas c, RecyclerView parent, State state) {} /* drawn after the item views */ public void onDrawOver(Canvas c, RecyclerView parent, State state) {} /* adjusts the item insets to give space if necessary for the decoration */ public void getItemOffsets(Rect outRect, View view, RecyclerView parent, State state) {} } BIG NOTA BENE : These methods are not called of each item individually but just once for the RecyclerView
22. ITEM ANIMATOR
23. public static abstract class ItemAnimator { abstract public void runPendingAnimations(); abstract public boolean animateRemove(ViewHolder holder); abstract public boolean animateAdd(ViewHolder holder); abstract public boolean animateMove(ViewHolder holder, int fromX, int fromY, int toX, int toY); abstract public boolean animateChange(ViewHolder oldHolder, ViewHolder newHolder, int fromLeft, int fromTop, int toLeft, int toTop); abstract public void endAnimation(ViewHolder item); abstract public void endAnimations(); abstract public boolean isRunning(); }
24. DEFAULT IMPLEMENTATION /** * This implementation of {@link RecyclerView.ItemAnimator} provides basic * animations on remove, add, and move events that happen to the items in * a RecyclerView. RecyclerView uses a DefaultItemAnimator by default. */ public class DefaultItemAnimator extends RecyclerView.ItemAnimator { /* REALLY INTERESTING CODE HERE */ }
25. CODE
26. LINKS ▸ https://github.com/kevinmcmahon/android-RecyclerView ▸ http://lucasr.org/2014/07/31/the-new-twowayview/ ▸ http://wiresareobsolete.com/2014/09/building-a-recyclerview- layoutmanager-part-1/
27. KEVIN MCMAHON @KLMCMAHON HTTP://ABOUT.ME/KEVINMCMAHON