我的问题是当Recycler View向上和向下滚动时
这是我如何在Fragment中设置My Recycler视图。
private void setRecyclerView() {
recyclerView.setHasFixedSize(true);
StaggeredGridLayoutManager layoutManager =
new StaggeredGridLayoutManager(2, 1);
recyclerView.setLayoutManager(layoutManager);
adapter = new TwitterTweetAdapter(getActivity());
// setting every thing false in item animator
recyclerView.setItemAnimator(new RecyclerView.ItemAnimator() {
@Override
public void runPendingAnimations() {
}
@Override
public boolean animateRemove(RecyclerView.ViewHolder viewHolder) {
return false;
}
@Override
public boolean animateAdd(RecyclerView.ViewHolder viewHolder) {
return false;
}
@Override
public boolean animateMove(RecyclerView.ViewHolder viewHolder, int i, int i2, int i3, int i4) {
return false;
}
@Override
public boolean animateChange(RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder viewHolder2, int i, int i2, int i3, int i4) {
return false;
}
@Override
public void endAnimation(RecyclerView.ViewHolder viewHolder) {
}
@Override
public void endAnimations() {
}
@Override
public boolean isRunning() {
return false;
}
});
recyclerView.setAdapter(adapter);
}
这是我的适配器类
在我的适配器中，我正在设置One Header
//我的ViewHolders
class Header extends RecyclerView.ViewHolder {
@Bind(R.id.feed_head)
CardView feedHeader;
@Bind(R.id.feed_header_count)
TextView userCount;
@Bind(R.id.feed_header_text)
TextView userText;
public TwitterHeader(View itemView) {
super(itemView);
ButterKnife.bind(this, itemView);
}
}
public static class RowViewHolder extends RecyclerView.ViewHolder {
@Bind(R.id.feed_row_view)
CardView feedRow;
@Bind(R.id.feed_image)
ImageView feedImage;
@Bind(R.id.video_play_icon)
ImageButton playButton;
@Bind(R.id.feed_description)
TextView feedDescription;
@Bind(R.id.feed_user_image)
ImageView userImage;
@Bind(R.id.feed_user_name)
TextView userName;
@Bind(R.id.feed_time)
TextView feedDate;
@Bind(R.id.feed_progress_bar)
ProgressBar progressBar;
public RowViewHolder(View itemView) {
super(itemView);
ButterKnife.bind(this, itemView);
}
}
//变量声明
private static final int TYPE_HEADER = 0;
private static final int TYPE_FEED = 1;
Context context;
private Activity activity;
private List<MockData> dataLists;
public static List<MockData> dataListsupdated;
int userSearchCount;
//构造函数
public FeedAdapter(Activity activity) {
this.activity = activity;
}
//设置数据列表
public void setDataList(List<MockData> dataLists, int userSearchCount, float density) {
this.dataLists = dataLists;
this.density = density;
this.userSearchCount = userSearchCount;
}
// onCreateViewHolder
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
if (viewType == TYPE_HEADER) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.feed_header, viewGroup, false);
return new Header(view);
} else {
View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.feed_row, viewGroup, false);
return new RowViewHolder(v);
}
}
// onBindViewHolder我将视图与数据绑定。
if (holder instanceof Header) {
Header header = (Header) holder;
if (userSearchCount == 20) {
header.userCount.setText(R.string.twitter_default_count);
} else {
header.userCount.setText(userSearchCount);
}
header.userText.setText(R.string.user);
header.feedHeader.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(activity, TwitterSearchActivity.class);
activity.startActivity(intent);
}
});
} else {
if (holder instanceof RowViewHolder) {
final RowViewHolder rowViewHolder = (RowViewHolder) holder;
final MockData responseList = dataLists.get(position);
rowWidth = rowViewHolder.feedImage.getWidth();
rowViewHolder.playButton.setVisibility(View.GONE);
if (responseList.text.startsWith("RT")) {
rowViewHolder.feedRow.setVisibility(View.GONE);
FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.WRAP_CONTENT);
params.setMargins(0, 0, 0, 0);
rowViewHolder.feed.setLayoutParams(params);
} else {
setRowImage(rowViewHolder, responseList);
rowViewHolder.feedDescription.setText(responseList.text);
rowViewHolder.userImage.setVisibility(View.VISIBLE);
Glide.with(activity)
.load(responseList.user.profileImageUrlHttps)
.into(rowViewHolder.userImage);
rowViewHolder.userName.setText(responseList.user.screenName);
Date date = new Date(responseList.createdAt);
DateFormat dateFormat = android.text.format.DateFormat.getDateFormat(activity.getApplicationContext());
rowViewHolder.feedDate.setText(dateFormat.format(date));
rowViewHolder.feedRow.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(position);
}
});
}
}
}
}
//设置行图像。
private void setRowImage(RowViewHolder rowViewHolder, Tweet responseList) {
if (responseList.entities.media != null) {
MediaEntity mediaEntity = responseList.entities.media.get(0);
if (mediaEntity.mediaUrlHttps != null) {
int height = mediaEntity.sizes.medium.h;
int width = mediaEntity.sizes.medium.w;
int ratio = width / 143;
int newHeight = (int) ((height / ratio) * density);
Glide.with(activity)
.load(mediaEntity.mediaUrlHttps)
.override(width, newHeight)
.placeholder(R.color.colorAccent)
.into(rowViewHolder.feedImage);
} else {
rowViewHolder.feedImage.setImageDrawable(null);
}
} else {
rowViewHolder.feedImage.setImageDrawable(null);
}
}
//查看条件以设置标题和行。
@Override
public int getItemViewType(int position) {
if (isPositionHeader(position))
return TYPE_HEADER;
return TYPE_FEED;
}
private boolean isPositionHeader(int position) {
return position == 0;
}
@Override
public int getItemCount() {
return dataLists == null ? 0 : dataLists.size();
}
}
答案 0 :(得分：3)
我在我的应用程序中有一个非常相似的适配器，我从Facebook而不是Twitter显示提要，首先，切换到Glide而不是Picasso，因为它使用RecyclerView提供了更好的缓存和图像加载，请检查THIS 。现在回到你的问题，在第一步调用你的适配器上的setHasStableIds（true），覆盖getItemId方法从你的适配器返回一个合适的长，因为你正在使用一个feed，你可以为postId计算一个哈希值或者某个字段唯一标识Feed中的每个帖子。我的Feed也有一个可选图像，这就是我有这两种方法的原因
public void setProfilePicture(String uri) {
//As per the solution discussed here http://stackoverflow.com/questions/32706246/recyclerview-adapter-and-glide-same-image-every-4-5-rows
if (uri != null) {
Glide.with(mContext)
.load(uri)
.asBitmap()
.transform(new CropCircleTransform(mContext))
.into(mProfilePicture);
} else {
Glide.clear(mProfilePicture);
mProfilePicture.setImageResource(R.drawable.com_facebook_profile_picture_blank_square);
}
}
public void setPostPicture(String uri) {
//As per the solution discussed here http://stackoverflow.com/questions/32706246/recyclerview-adapter-and-glide-same-image-every-4-5-rows
if (uri != null) {
Glide.with(mContext)
.load(uri)
.asBitmap()
.transform(new CropTransformation(mContext, mPostImageWidth, mPostImageHeight))
.into(mPostPicture);
} else {
Glide.clear(mPostPicture);
mPostPicture.setImageDrawable(null);
}
}
然后你要做的就是从onBindViewHolder调用这些方法来设置Image。 Post是我的对象，其中包含单个帖子的详细信息，例如姓名，用户ID，人物图片的图片网址和可选的帖子图片的图片网址。如果您再遇到任何问题，请告诉我。
@Override
public void onBindViewHolder(ItemHolder holder, int position) {
Post post = mResults.get(position);
holder.setUserName(post.getUserName());
holder.setUpdatedTime(post.getUpdatedTime());
holder.setMessage(post.getMessage(), mState, position);
holder.setPostPicture(post.getPicture());
holder.setProfilePicture(post.getUserPicture());
// Check for an expanded view, collapse if you find one
}
答案 1 :(得分：2)
如果您看到RecyclerView的源代码超过HERE，请导航到包含这些行的第3028行
/**
* Returns a unique key to be used while handling change animations.
* It might be child's position or stable id depending on the adapter type.
*/
long getChangedHolderKey(ViewHolder holder) {
return mAdapter.hasStableIds() ? holder.getItemId() : holder.mPosition;
}
和包含此
的源文件中的第5279行/**
* Return the stable ID for the item at <code>position</code>. If {@link #hasStableIds()}
* would return false this method should return {@link #NO_ID}. The default implementation
* of this method returns {@link #NO_ID}.
*
* @param position Adapter position to query
* @return the stable ID of the item at position
*/
public long getItemId(int position) {
return NO_ID;
}
它清楚地表明覆盖setHasStableIds后需要覆盖getItemId方法。当您向上和向下滚动时，让您的RecyclerView中的每个项目显示正确的项目getItemId无法返回一个位置或更糟糕的是停止。确保返回标识数据集中每一行的唯一long值。
这个独特的价值是什么？
这对于动画和在正确位置显示正确的行都很重要。希望有助于解决您的问题
答案 2 :(得分：1)
您遇到的问题是您没有实施getItemID，或者您没有正确实施它。
如果您将setHasStableIds设置为true，并且未实现getItemId为列表中的每个项目返回唯一long，则RecyclerView 将重复项目。这是因为getItemID的默认实现为列表中的所有项返回-1，因此，在视图被回收后调用onBindViewHolder时，它将返回ViewHolder显示的最后一个事物的缓存视图。
实现此目的的一种简单方法就是返回绑定到ViewHolder的列表中对象的哈希码。
@Override
public long getItemId(int position) {
Object listItem = listItems.get(position);
return listItem.hashCode();
}
显然，这意味着对于该特定对象，您必须覆盖它的equals()和hashCode()方法，以使每个对象都是唯一的。一个好主意是String显示何时从与对象名称连接的数据库创建它。
答案 3 :(得分：0)
在您的recyclerview适配器中覆盖这两个方法，并更改getItemViewType的代码，如下所示。
@Override
public long getItemId(int position) {
return position;
}
@Override
public int getItemViewType(int position) {
if (isPositionHeader(position)) {
return TYPE_HEADER;
}
else {
return position;
}
}
我也有同样的问题。做这个。这肯定会解决你的问题。