samples/Support7Demos/src/com/example/android/supportv7/widget/RecyclerViewActivity.java - platform/frameworks/support - Git at Google

 /*
  * Copyright (C) 2013 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */


 package com.example.android.supportv7.widget;

 import android.R;
 import android.app.Activity;
 import android.content.Context;
 import android.graphics.Rect;
 import android.os.Bundle;
 import android.support.v4.view.MenuItemCompat;
 import android.support.v7.widget.RecyclerView;
 import android.util.DisplayMetrics;
 import android.util.TypedValue;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.View.MeasureSpec;
 import android.widget.TextView;
 import com.example.android.supportv7.Cheeses;

 import java.util.ArrayList;
 import java.util.Collections;

 public class RecyclerViewActivity extends Activity {
     private RecyclerView mRecyclerView;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);

         final RecyclerView rv = new RecyclerView(this);
         rv.setLayoutManager(new MyLayoutManager(this));
         rv.setHasFixedSize(true);
         rv.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
                 ViewGroup.LayoutParams.MATCH_PARENT));
         rv.setAdapter(new MyAdapter(Cheeses.sCheeseStrings));
         setContentView(rv);

         mRecyclerView = rv;
     }

     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
         super.onCreateOptionsMenu(menu);
         MenuItemCompat.setShowAsAction(menu.add("Layout"), MenuItemCompat.SHOW_AS_ACTION_IF_ROOM);
         return true;
     }

     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
         mRecyclerView.requestLayout();
         return super.onOptionsItemSelected(item);
     }

     private static final int SCROLL_DISTANCE = 80; // dp

     /**
      * A basic ListView-style LayoutManager.
      */
     class MyLayoutManager extends RecyclerView.LayoutManager {
         private static final String TAG = "MyLayoutManager";
         private int mFirstPosition;
         private final int mScrollDistance;

         public MyLayoutManager(Context c) {
             final DisplayMetrics dm = c.getResources().getDisplayMetrics();
             mScrollDistance = (int) (SCROLL_DISTANCE * dm.density + 0.5f);
         }

         @Override
         public void layoutChildren(RecyclerView.Adapter adapter, RecyclerView.Recycler recycler) {
             final int parentBottom = getHeight() - getPaddingBottom();

             final View oldTopView = getChildCount() > 0 ? getChildAt(0) : null;
             int oldTop = getPaddingTop();
             if (oldTopView != null) {
                 oldTop = oldTopView.getTop();
             }

             recycler.scrapAllViewsAttached();

             int top = oldTop;
             int bottom;
             final int left = getPaddingLeft();
             final int right = getWidth() - getPaddingRight();

             final int count = adapter.getItemCount();
             for (int i = 0; mFirstPosition + i < count && top < parentBottom; i++, top = bottom) {
                 View v = recycler.getViewForPosition(adapter, mFirstPosition + i);
                 addView(v, i);
                 v.measure(MeasureSpec.makeMeasureSpec(right - left, MeasureSpec.EXACTLY),
                         MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
                 bottom = top + v.getMeasuredHeight();
                 v.layout(left, top, right, bottom);
             }

             recycler.detachDirtyScrapViews();
         }

         @Override
         public RecyclerView.LayoutParams generateDefaultLayoutParams() {
             return new RecyclerView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
                     ViewGroup.LayoutParams.WRAP_CONTENT);
         }

         @Override
         public boolean canScrollVertically() {
             return true;
         }

         @Override
         public int scrollVerticallyBy(int dy, RecyclerView.Adapter adapter,
                 RecyclerView.Recycler recycler) {
             if (getChildCount() == 0) {
                 return 0;
             }

             int scrolled = 0;
             final int left = getPaddingLeft();
             final int right = getWidth() - getPaddingRight();
             if (dy < 0) {
                 while (scrolled > dy) {
                     final View topView = getChildAt(0);
                     final int hangingTop = Math.max(-topView.getTop(), 0);
                     final int scrollBy = Math.min(scrolled - dy, hangingTop);
                     scrolled -= scrollBy;
                     offsetChildrenVertical(scrollBy);
                     if (mFirstPosition > 0 && scrolled > dy) {
                         mFirstPosition--;
                         View v = recycler.getViewForPosition(adapter, mFirstPosition);
                         addView(v, 0);
                         v.measure(MeasureSpec.makeMeasureSpec(right - left, MeasureSpec.EXACTLY),
                                 MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
                         final int bottom = topView.getTop(); // TODO decorated top?
                         final int top = bottom - v.getMeasuredHeight();
                         v.layout(left, top, right, bottom);
                     } else {
                         break;
                     }
                 }
             } else if (dy > 0) {
                 final int parentHeight = getHeight();
                 while (scrolled < dy) {
                     final View bottomView = getChildAt(getChildCount() - 1);
                     final int hangingBottom = Math.max(bottomView.getBottom() - parentHeight, 0);
                     final int scrollBy = -Math.min(dy - scrolled, hangingBottom);
                     scrolled -= scrollBy;
                     offsetChildrenVertical(scrollBy);
                     if (scrolled < dy && getItemCount() > mFirstPosition + getChildCount()) {
                         View v = recycler.getViewForPosition(adapter,
                                 mFirstPosition + getChildCount());
                         final int top = getChildAt(getChildCount() - 1).getBottom();
                         addView(v);
                         v.measure(MeasureSpec.makeMeasureSpec(right - left, MeasureSpec.EXACTLY),
                                 MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
                         final int bottom = top + v.getMeasuredHeight();
                         v.layout(left, top, right, bottom);
                     } else {
                         break;
                     }
                 }
             }
             detachAndScrapViewsOutOfBounds(recycler);
             return scrolled;
         }

         @Override
         public View onFocusSearchFailed(View focused, int direction,
                 RecyclerView.Adapter adapter, RecyclerView.Recycler recycler) {
             final int oldCount = getChildCount();

             if (oldCount == 0) {
                 return null;
             }

             final int left = getPaddingLeft();
             final int right = getWidth() - getPaddingRight();

             View toFocus = null;
             int newViewsHeight = 0;
             if (direction == View.FOCUS_UP || direction == View.FOCUS_BACKWARD) {
                 while (mFirstPosition > 0 && newViewsHeight < mScrollDistance) {
                     mFirstPosition--;
                     View v = recycler.getViewForPosition(adapter, mFirstPosition);
                     final int bottom = getChildAt(0).getTop(); // TODO decorated top?
                     addView(v, 0);
                     v.measure(MeasureSpec.makeMeasureSpec(right - left, MeasureSpec.EXACTLY),
                             MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
                     final int top = bottom - v.getMeasuredHeight();
                     v.layout(left, top, right, bottom);
                     if (v.isFocusable()) {
                         toFocus = v;
                         break;
                     }
                 }
             }
             if (direction == View.FOCUS_DOWN || direction == View.FOCUS_FORWARD) {
                 while (mFirstPosition + getChildCount() < getItemCount() &&
                         newViewsHeight < mScrollDistance) {
                     View v = recycler.getViewForPosition(adapter, mFirstPosition + getChildCount());
                     final int top = getChildAt(getChildCount() - 1).getBottom();
                     addView(v);
                     v.measure(MeasureSpec.makeMeasureSpec(right - left, MeasureSpec.EXACTLY),
                             MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
                     final int bottom = top + v.getMeasuredHeight();
                     v.layout(left, top, right, bottom);
                     if (v.isFocusable()) {
                         toFocus = v;
                         break;
                     }
                 }
             }

             return toFocus;
         }

         public void detachAndScrapViewsOutOfBounds(RecyclerView.Recycler recycler) {
             final int childCount = getChildCount();
             final int parentWidth = getWidth();
             final int parentHeight = getHeight();
             boolean foundFirst = false;
             int first = 0;
             int last = 0;
             for (int i = 0; i < childCount; i++) {
                 final View v = getChildAt(i);
                 if (v.hasFocus() || (v.getRight() >= 0 && v.getLeft() <= parentWidth &&
                         v.getBottom() >= 0 && v.getTop() <= parentHeight)) {
                     if (!foundFirst) {
                         first = i;
                         foundFirst = true;
                     }
                     last = i;
                 }
             }
             for (int i = childCount - 1; i > last; i--) {
                 recycler.detachAndScrapView(getChildAt(i));
             }
             for (int i = first - 1; i >= 0; i--) {
                 recycler.detachAndScrapView(getChildAt(i));
             }
             if (getChildCount() == 0) {
                 mFirstPosition = 0;
             } else {
                 mFirstPosition += first;
             }
         }
     }

     class MyAdapter extends RecyclerView.Adapter {
         private int mBackground;
         private ArrayList<String> mValues;

         public MyAdapter(String[] strings) {
             TypedValue val = new TypedValue();
             RecyclerViewActivity.this.getTheme().resolveAttribute(
                     R.attr.selectableItemBackground, val, true);
             mBackground = val.resourceId;
             mValues = new ArrayList<String>();
             Collections.addAll(mValues, strings);
         }

         @Override
         public RecyclerView.ViewHolder createViewHolder(ViewGroup parent, int viewType) {
             final ViewHolder h = new ViewHolder(new TextView(RecyclerViewActivity.this));
             h.textView.setMinimumHeight(128);
             h.textView.setFocusable(true);
             h.textView.setBackgroundResource(mBackground);
             h.textView.setOnClickListener(new View.OnClickListener() {
                 @Override
                 public void onClick(View v) {
                     final int pos = h.getPosition();
                     if (mValues.size() > pos + 1) {
                         final String t = mValues.get(pos);
                         mValues.set(pos, mValues.get(pos + 1));
                         mValues.set(pos + 1, t);
                         notifyDataSetChanged();
                     }
                 }
             });
             return h;
         }

         @Override
         public void bindViewHolder(RecyclerView.ViewHolder holder, int position) {
             ((ViewHolder) holder).textView.setText(mValues.get(position));
         }

         @Override
         public int getItemCount() {
             return mValues.size();
         }
     }

     static class ViewHolder extends RecyclerView.ViewHolder {
         public TextView textView;

         public ViewHolder(TextView v) {
             super(v);
             textView = v;
         }
     }
 }
	/*
	* Copyright (C) 2013 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/


	package com.example.android.supportv7.widget;

	import android.R;
	import android.app.Activity;
	import android.content.Context;
	import android.graphics.Rect;
	import android.os.Bundle;
	import android.support.v4.view.MenuItemCompat;
	import android.support.v7.widget.RecyclerView;
	import android.util.DisplayMetrics;
	import android.util.TypedValue;
	import android.view.Menu;
	import android.view.MenuItem;
	import android.view.View;
	import android.view.ViewGroup;
	import android.view.View.MeasureSpec;
	import android.widget.TextView;
	import com.example.android.supportv7.Cheeses;

	import java.util.ArrayList;
	import java.util.Collections;

	public class RecyclerViewActivity extends Activity {
	private RecyclerView mRecyclerView;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);

	final RecyclerView rv = new RecyclerView(this);
	rv.setLayoutManager(new MyLayoutManager(this));
	rv.setHasFixedSize(true);
	rv.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
	ViewGroup.LayoutParams.MATCH_PARENT));
	rv.setAdapter(new MyAdapter(Cheeses.sCheeseStrings));
	setContentView(rv);

	mRecyclerView = rv;
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
	super.onCreateOptionsMenu(menu);
	MenuItemCompat.setShowAsAction(menu.add("Layout"), MenuItemCompat.SHOW_AS_ACTION_IF_ROOM);
	return true;
	}

	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
	mRecyclerView.requestLayout();
	return super.onOptionsItemSelected(item);
	}

	private static final int SCROLL_DISTANCE = 80; // dp

	/**
	* A basic ListView-style LayoutManager.
	*/
	class MyLayoutManager extends RecyclerView.LayoutManager {
	private static final String TAG = "MyLayoutManager";
	private int mFirstPosition;
	private final int mScrollDistance;

	public MyLayoutManager(Context c) {
	final DisplayMetrics dm = c.getResources().getDisplayMetrics();
	mScrollDistance = (int) (SCROLL_DISTANCE * dm.density + 0.5f);
	}

	@Override
	public void layoutChildren(RecyclerView.Adapter adapter, RecyclerView.Recycler recycler) {
	final int parentBottom = getHeight() - getPaddingBottom();

	final View oldTopView = getChildCount() > 0 ? getChildAt(0) : null;
	int oldTop = getPaddingTop();
	if (oldTopView != null) {
	oldTop = oldTopView.getTop();
	}

	recycler.scrapAllViewsAttached();

	int top = oldTop;
	int bottom;
	final int left = getPaddingLeft();
	final int right = getWidth() - getPaddingRight();

	final int count = adapter.getItemCount();
	for (int i = 0; mFirstPosition + i < count && top < parentBottom; i++, top = bottom) {
	View v = recycler.getViewForPosition(adapter, mFirstPosition + i);
	addView(v, i);
	v.measure(MeasureSpec.makeMeasureSpec(right - left, MeasureSpec.EXACTLY),
	MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
	bottom = top + v.getMeasuredHeight();
	v.layout(left, top, right, bottom);
	}

	recycler.detachDirtyScrapViews();
	}

	@Override
	public RecyclerView.LayoutParams generateDefaultLayoutParams() {
	return new RecyclerView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
	ViewGroup.LayoutParams.WRAP_CONTENT);
	}

	@Override
	public boolean canScrollVertically() {
	return true;
	}

	@Override
	public int scrollVerticallyBy(int dy, RecyclerView.Adapter adapter,
	RecyclerView.Recycler recycler) {
	if (getChildCount() == 0) {
	return 0;
	}

	int scrolled = 0;
	final int left = getPaddingLeft();
	final int right = getWidth() - getPaddingRight();
	if (dy < 0) {
	while (scrolled > dy) {
	final View topView = getChildAt(0);
	final int hangingTop = Math.max(-topView.getTop(), 0);
	final int scrollBy = Math.min(scrolled - dy, hangingTop);
	scrolled -= scrollBy;
	offsetChildrenVertical(scrollBy);
	if (mFirstPosition > 0 && scrolled > dy) {
	mFirstPosition--;
	View v = recycler.getViewForPosition(adapter, mFirstPosition);
	addView(v, 0);
	v.measure(MeasureSpec.makeMeasureSpec(right - left, MeasureSpec.EXACTLY),
	MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
	final int bottom = topView.getTop(); // TODO decorated top?
	final int top = bottom - v.getMeasuredHeight();
	v.layout(left, top, right, bottom);
	} else {
	break;
	}
	}
	} else if (dy > 0) {
	final int parentHeight = getHeight();
	while (scrolled < dy) {
	final View bottomView = getChildAt(getChildCount() - 1);
	final int hangingBottom = Math.max(bottomView.getBottom() - parentHeight, 0);
	final int scrollBy = -Math.min(dy - scrolled, hangingBottom);
	scrolled -= scrollBy;
	offsetChildrenVertical(scrollBy);
	if (scrolled < dy && getItemCount() > mFirstPosition + getChildCount()) {
	View v = recycler.getViewForPosition(adapter,
	mFirstPosition + getChildCount());
	final int top = getChildAt(getChildCount() - 1).getBottom();
	addView(v);
	v.measure(MeasureSpec.makeMeasureSpec(right - left, MeasureSpec.EXACTLY),
	MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
	final int bottom = top + v.getMeasuredHeight();
	v.layout(left, top, right, bottom);
	} else {
	break;
	}
	}
	}
	detachAndScrapViewsOutOfBounds(recycler);
	return scrolled;
	}

	@Override
	public View onFocusSearchFailed(View focused, int direction,
	RecyclerView.Adapter adapter, RecyclerView.Recycler recycler) {
	final int oldCount = getChildCount();

	if (oldCount == 0) {
	return null;
	}

	final int left = getPaddingLeft();
	final int right = getWidth() - getPaddingRight();

	View toFocus = null;
	int newViewsHeight = 0;
	if (direction == View.FOCUS_UP \|\| direction == View.FOCUS_BACKWARD) {
	while (mFirstPosition > 0 && newViewsHeight < mScrollDistance) {
	mFirstPosition--;
	View v = recycler.getViewForPosition(adapter, mFirstPosition);
	final int bottom = getChildAt(0).getTop(); // TODO decorated top?
	addView(v, 0);
	v.measure(MeasureSpec.makeMeasureSpec(right - left, MeasureSpec.EXACTLY),
	MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
	final int top = bottom - v.getMeasuredHeight();
	v.layout(left, top, right, bottom);
	if (v.isFocusable()) {
	toFocus = v;
	break;
	}
	}
	}
	if (direction == View.FOCUS_DOWN \|\| direction == View.FOCUS_FORWARD) {
	while (mFirstPosition + getChildCount() < getItemCount() &&
	newViewsHeight < mScrollDistance) {
	View v = recycler.getViewForPosition(adapter, mFirstPosition + getChildCount());
	final int top = getChildAt(getChildCount() - 1).getBottom();
	addView(v);
	v.measure(MeasureSpec.makeMeasureSpec(right - left, MeasureSpec.EXACTLY),
	MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
	final int bottom = top + v.getMeasuredHeight();
	v.layout(left, top, right, bottom);
	if (v.isFocusable()) {
	toFocus = v;
	break;
	}
	}
	}

	return toFocus;
	}

	public void detachAndScrapViewsOutOfBounds(RecyclerView.Recycler recycler) {
	final int childCount = getChildCount();
	final int parentWidth = getWidth();
	final int parentHeight = getHeight();
	boolean foundFirst = false;
	int first = 0;
	int last = 0;
	for (int i = 0; i < childCount; i++) {
	final View v = getChildAt(i);
	if (v.hasFocus() \|\| (v.getRight() >= 0 && v.getLeft() <= parentWidth &&
	v.getBottom() >= 0 && v.getTop() <= parentHeight)) {
	if (!foundFirst) {
	first = i;
	foundFirst = true;
	}
	last = i;
	}
	}
	for (int i = childCount - 1; i > last; i--) {
	recycler.detachAndScrapView(getChildAt(i));
	}
	for (int i = first - 1; i >= 0; i--) {
	recycler.detachAndScrapView(getChildAt(i));
	}
	if (getChildCount() == 0) {
	mFirstPosition = 0;
	} else {
	mFirstPosition += first;
	}
	}
	}

	class MyAdapter extends RecyclerView.Adapter {
	private int mBackground;
	private ArrayList<String> mValues;

	public MyAdapter(String[] strings) {
	TypedValue val = new TypedValue();
	RecyclerViewActivity.this.getTheme().resolveAttribute(
	R.attr.selectableItemBackground, val, true);
	mBackground = val.resourceId;
	mValues = new ArrayList<String>();
	Collections.addAll(mValues, strings);
	}

	@Override
	public RecyclerView.ViewHolder createViewHolder(ViewGroup parent, int viewType) {
	final ViewHolder h = new ViewHolder(new TextView(RecyclerViewActivity.this));
	h.textView.setMinimumHeight(128);
	h.textView.setFocusable(true);
	h.textView.setBackgroundResource(mBackground);
	h.textView.setOnClickListener(new View.OnClickListener() {
	@Override
	public void onClick(View v) {
	final int pos = h.getPosition();
	if (mValues.size() > pos + 1) {
	final String t = mValues.get(pos);
	mValues.set(pos, mValues.get(pos + 1));
	mValues.set(pos + 1, t);
	notifyDataSetChanged();
	}
	}
	});
	return h;
	}

	@Override
	public void bindViewHolder(RecyclerView.ViewHolder holder, int position) {
	((ViewHolder) holder).textView.setText(mValues.get(position));
	}

	@Override
	public int getItemCount() {
	return mValues.size();
	}
	}

	static class ViewHolder extends RecyclerView.ViewHolder {
	public TextView textView;

	public ViewHolder(TextView v) {
	super(v);
	textView = v;
	}
	}
	}