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RECYCLERVIEW
ANDROID LISTENER NOVEMBER 2014
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No content
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A FLEXIBLE VIEW FOR
PROVIDING A LIMITED WINDOW
INTO A LARGE DATA SET.
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Yeah, that's called a
LISTVIEW!
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REDUCES
COUPLING
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DELEGATION
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MAKES IT EASY TO DO
THE RIGHT THING
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THE 5 CLASSES
YOU'LL MEET...
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ADAPTER
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2 ROLES
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PROVIDING DATA
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PROVIDING LAYOUTS
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public VH onCreateViewHolder(ViewGroup parent, int viewType)
public void onBindViewHolder(VH holder, int position)
public int getItemCount()
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VIEW HOLDER
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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);
}
}
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LAYOUT MANAGER
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ATTACHING
MEASURING
LAYING OUT
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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) ");
}
}
}
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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 */
}
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ITEM
DECORATION
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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
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ITEM
ANIMATOR
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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();
}
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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 */
}
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CODE
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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/
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KEVIN MCMAHON
@KLMCMAHON
HTTP://ABOUT.ME/KEVINMCMAHON