java.lang.NullPointerException: Attempt to write to field 'int android.support.v7.widget.RecyclerView$ViewHolder.mItemViewType
, int position) { viewHolder.textView .setText(items.get (position)); }...因此我们发现，这个adapter的核心代码在与onBindViewHolder（）中，作用是将数据跟视图（ViewHolder）绑定，可以给子类提供一个bindData（）抽象方法。...重头戏在ViewHolder上！RecyclerView强制我们使用ViewHolder模式，然而缺不可避免地要写findViewById代码，有没有办法不写这样的代码呢？...甚至连ViewHolder都不写呢？当然可以！...public class RecyclerViewHolder extends RecyclerView.ViewHolder { private SparseArray mViews
前言 本文主要通过如下几个方面讲解RecyclerView缓存机制： ViewHolder 缓存架构 Recycler.recycleViewHolderInternal(ViewHolder holder...ViewHolder 1.1 作用 ViewHolder是对RecyclerView上的ItemView的封装，它是RecyclerView缓存的载体。...：ViewHolder对应的标记位 List mPayloads：实现局部刷新 Recycler mScrapContainer：如果不为空，表示ViewHolder是存放在Scrap缓存中...做动画时需要保证ViewHolder不能被回收掉 FLAG_RETURNED_FROM_SCRAP：从scrap缓存中获取到的ViewHolder FLAG_IGNORE：如果回收该类型的ViewHolder...ViewHolder 如果id匹配上了 type没匹配上，将该ViewHolder回收掉 ?
为左边滑出；CardConfig.SWIPED_RIGHT 为右边滑出 */ void onSwiped(RecyclerView.ViewHolder viewHolder, T t...viewHolder, RecyclerView.ViewHolder target) 和 onSwiped(RecyclerView.ViewHolder viewHolder, int direction...但是因为在上面我们对于 dragFlags 配置的是 0 ，所以在 onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder...@Override public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder...target) { return false; } 这样，我们就把目光投向 onSwiped(RecyclerView.ViewHolder viewHolder, int direction
adapter中自己去提供回调 废话不多说，直接看代码： public class GalleryAdapter extends RecyclerView.Adapter<GalleryAdapter.ViewHolder...跟listView里面一样 属性是item 布局里面各个视图控件 */ public static class ViewHolder extends RecyclerView.ViewHolder...viewHolder = new ViewHolder(view); viewHolder.mImg = (ImageView) view.findViewById(R.id.id_index_gallery_item_image...(final ViewHolder viewHolder, final int i) { // 布局填充数据 viewHolder.mImg.setImageResource(mDatas.get...= null) { viewHolder.itemView.setOnClickListener(new OnClickListener() { @Override public
, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) { return false; }...onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target)...下面就是 onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target...所以在 onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target...RecyclerView.ViewHolder viewHolder, int direction) { int position = viewHolder.getAdapterPosition
viewHolder, RecyclerView.ViewHolder target) { Log.i(TAG, "onMove viewHolder.getAdapterPosition()...is:" + viewHolder.getAdapterPosition()); int itemViewType = viewHolder.getAdapterPosition();...viewHolder) { Log.i(TAG, "getMovementFlags viewHolder.getAdapterPosition() is:" + viewHolder.getAdapterPosition...viewHolder, RecyclerView.ViewHolder target) { Log.i(TAG, "onMove viewHolder.getAdapterPosition() is:...(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) { super.clearView(recyclerView, viewHolder
viewHolder = getViewHolder(position, convertView, parent); convert(viewHolder, getItem(position...) , position); return viewHolder.getConvertView(); } public abstract void convert(ViewHolder...ViewGroup parent) { return ViewHolder.get(mContext, convertView, parent, mItemLayoutId,...position); } } ViewHolder： public class ViewHolder { private final SparseArray<View mViews; private...int mPosition; private View mConvertView; private ViewHolder(Context context, ViewGroup parent,
3，ListView实现了两级缓存，提升view性能 布局 ListView 系统api只提供了纵向列表显示，无法显示横行或者网格布局等 ViewHolder机制 ListView 没有默认实现ViewHolder...机制.关于ViewHolder机制后面有机会我会专门写一篇文章来介绍，这里先简单介绍。...viewHolder = null; if (convertView == null) { viewHolder = new ViewHolder();...); } viewHolder = (ViewHolder) convertView.getTag(); /* *...,ViewHolder的相关机制RecyclerView已经默认给实现了。
// 该方法就是 开发者 自定义 Callback 中的 // public float getMoveThreshold(@NonNull RecyclerView.ViewHolder viewHolder...viewHolder, @NonNull RecyclerView.ViewHolder target) 先获取拖动的起始位置和目标位置 , 然后传入...viewHolder, // @NonNull RecyclerView.ViewHolder target) 方法 // 一般是拖动交换数据...viewHolder = mSelected; if (viewHolder == null) { return; }...// 执行到此处说明拖动判定成功 List swapTargets = findSwapTargets(viewHolder); if
本章主要分为以下三点： 打造通用的ViewHolder优化ListView性能 使用泛型Adapter适应不同布局的ListView C#委托和Java匿名内部类的比较 打造通用的ViewHolder...(context, parent, itemLayoutId, position); } else { ViewHolder holder = (ViewHolder...的构造方法中初始化变量，并将ListView的布局view的Tag设置成viewholder的实例 Get方法使用单例模式初始化ViewHolder GetView泛型方法获取ListView布局中的空间...viewHolder = ViewHolder.Get(mContext, convertView, parent, mItemLayoutId, position); convert(viewHolder...viewHolder) { viewHolder.SetText(Resource.Id.tv_news_title, model.Title); viewHolder.SetText
extends RecyclerView.ViewHolder { TextView text; public ViewHolder(@NonNull...viewHolder, int actionState) { super.onSelectedChanged(viewHolder, actionState); }...viewHolder, int fromPos, @NonNull RecyclerView.ViewHolder target, int toPos, int x, int y) {...viewHolder, @NonNull RecyclerView.ViewHolder target) { return false; } @Override...public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) { } @Override
但从Recycler中获取一个ViewHolder的前提是Recycler中要有ViewHolder。那Recycler中是如何有ViewHolder的呢？...但比较疑惑的可能就是上述ViewHolder缓存集合中什么时候会保存ViewHolder。接下来分几个RecyclerView的具体情形，来一点一点弄明白这些ViewHolder缓存集合的问题。...很明显在这种情形下Recycler中是不会存在任何可复用的ViewHolder。所以所有的ViewHolder都是新创建的。...那这些创建的ViewHolder会缓存起来吗？ 这时候新创建的这些ViewHolder是不会被缓存起来的。...所以在普通的滚动复用的情况下，ViewHolder的复用主要来自于mCacheViews集合, 旧的ViewHolder会被放到mCacheViews集合, mCacheViews集合挤出来的更老的ViewHolder
viewHolder, ViewHolder target); //和滑动有关,可用于实现swipe功能 public abstract void onSwiped(ViewHolder viewHolder...void clearView(RecyclerView recyclerView, ViewHolder viewHolder) {} 当创建完ItemTouchHelper.Callback的实现类...source, RecyclerView.ViewHolder target); //数据删除 void onItemDissmiss(RecyclerView.ViewHolder source...viewHolder) { super.clearView(recyclerView, viewHolder); if (!...viewHolder) { //当拖拽选中时放大选中的view viewHolder.itemView.setScaleX(1.2f); viewHolder.itemView.setScaleY
holder.shouldIgnore()) { holder.addFlags(ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID...包括当前所有被填充表项及离屏缓存中的 ViewHolder 实例。无效化体现在代码上即是为 ViewHolder 添加 FLAG_UPDATE 和 FLAG_INVALID 标志位。...viewHolder.isRemoved() && !...// 从缓存获取 ViewHolder 实例并绑定数据 ViewHolder tryGetViewHolderForPositionByDeadline(int position, boolean...包括当前所有被填充表项及离屏缓存中的 ViewHolder 实例。无效化体现在代码上即是为 ViewHolder 添加 FLAG_UPDATE 和 FLAG_INVALID 标志位。
viewHolder = new ViewHolder(view); return viewHolder; } @Override public void onBindViewHolder...(@NonNull final ViewHolder viewHolder, final int i) { if (itemsBeanList !...(""); } else { viewHolder.text_content.setText(itemsBean.getItemName());..., currentStarCount, 1, i); } }); viewHolder.iv_comment_star_..., currentStarCount, 1, i); } }); viewHolder.iv_comment_star_
viewHolder = (ProgressViewHolder)holder; viewHolder.progressBar.setIndeterminate(true); }...){ ImageViewHolder viewHolder = (ImageViewHolder)holder; viewHolder.title.setText(list.get(position...).getTitle()); viewHolder.time.setText(list.get(position).getTime()); setItemImage(viewHolder, list...viewHolder, List<News list, int position){ viewHolder.imageMiddle.setVisibility(View.VISIBLE); viewHolder.imageRight.setVisibility...); viewHolder.imageMiddle.setVisibility(View.GONE); viewHolder.imageRight.setVisibility(View.GONE);
onBindViewHolder(@NonNull ViewHolder viewHolder, int i) { BundleCodeInfoModel bundleCodeInfoModel...= mBundleCodeInfoModel.get(i); viewHolder.perfPackId1.setText("包装记录id:"); viewHolder.perfPackId2....setText(String.valueOf(bundleCodeInfoModel.getPerfPackId())); viewHolder.steelGrade1.setText...viewHolder.packRootCount1.setText("包装根数:"); viewHolder.packRootCount2.setText(String.valueOf...viewHolder.INSP_VALUE_NAME.setText(model.INSP_VALUE_NAME); xxx viewHolder.JUDGE_RESULT.setText
省去了自己编写ViewHolder等大量的重复的代码。 可以通过holder.getView(id)拿到任何控件。...ViewHolder中封装了大量的常用的方法，比如holder.setText(id,text)，holder.setOnClickListener(id,listener)等，可以支持使用。...viewHolder = ViewHolder.get(mContext, convertView, parent, 43 layoutId, position); 44...convert(viewHolder, getItem(position)); 45 return viewHolder.getConvertView(); 46...(context, parent, layoutId, position); 44 } else { 45 ViewHolder holder = (ViewHolder
viewHolder, RecyclerView.ViewHolder target) { } @Override public void onSwiped(RecyclerView.ViewHolder...@Override public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder...target) { int fromPosition = viewHolder.getAdapterPosition();//得到拖动ViewHolder的position int...： @Override public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState...原来如此，我们可以在item的长按事件中得到当前item的ViewHolder ，然后调用ItemTouchHelper.startDrag(ViewHolder vh)就可以实现拖拽了，那就这么办：
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