使用RecyclerView创建动态列表:

当我们创建一个RecyclerView时。适配器我们必须指定ViewHolder,它将绑定到适配器。

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {

    private String[] mDataset;

    public MyAdapter(String[] myDataset) {
        mDataset = myDataset;
    }

    public static class ViewHolder extends RecyclerView.ViewHolder {
        public TextView mTextView;
        public ViewHolder(TextView v) {
            super(v);
            mTextView = v;
        }
    }

    @Override
    public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.some_layout, parent, false);

        //findViewById...

        ViewHolder vh = new ViewHolder(v);
        return vh;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        holder.mTextView.setText(mDataset[position]);
    }

    @Override
    public int getItemCount() {
        return mDataset.length;
    }
}

有可能创建多个视图类型的RecyclerView吗?


当前回答

你可以使用这个图书馆:https://github.com/vivchar/RendererRecyclerViewAdapter

mRecyclerViewAdapter = new RendererRecyclerViewAdapter(); /* Included from library */
mRecyclerViewAdapter.registerRenderer(new SomeViewRenderer(SomeModel.TYPE, this));
mRecyclerViewAdapter.registerRenderer(...); /* You can use several types of cells */

对于每一个项目,你应该实现一个ViewRenderer, ViewHolder, SomeModel:

ViewHolder -它是回收器视图的一个简单视图持有者。

SomeModel -它是你的模型与ItemModel接口

public class SomeViewRenderer extends ViewRenderer<SomeModel, SomeViewHolder> {

    public SomeViewRenderer(final int type, final Context context) {
        super(type, context);
    }

    @Override
    public void bindView(@NonNull final SomeModel model, @NonNull final SomeViewHolder holder) {
        holder.mTitle.setText(model.getTitle());
    }

    @NonNull
    @Override
    public SomeViewHolder createViewHolder(@Nullable final ViewGroup parent) {
        return new SomeViewHolder(LayoutInflater.from(getContext()).inflate(R.layout.some_item, parent, false));
    }
}

有关更多详细信息,您可以查看文档。

其他回答

您可以通过使getItemViewType()返回该位置的预期viewType值来处理multipleViewTypes RecyclerAdapter。

我准备了一个MultipleViewTypeAdapter用于构造一个MCQ列表的考试,它可能抛出一个可能有两个或多个有效答案(复选框选项)和一个单一答案问题(单选按钮选项)的问题。

为此,我从API响应中获得问题的类型,并使用它来决定我必须为该问题显示哪个视图。

public class MultiViewTypeAdapter extends RecyclerView.Adapter {

    Context mContext;
    ArrayList<Question> dataSet;
    ArrayList<String> questions;
    private Object radiobuttontype1;


    //Viewholder to display Questions with checkboxes
    public static class Checkboxtype2 extends RecyclerView.ViewHolder {
        ImageView imgclockcheck;
        CheckBox checkbox;

        public Checkboxtype2(@NonNull View itemView) {
            super(itemView);
            imgclockcheck = (ImageView) itemView.findViewById(R.id.clockout_cbox_image);
            checkbox = (CheckBox) itemView.findViewById(R.id.clockout_cbox);
        }
    }

    //Viewholder to display Questions with radiobuttons

    public static class Radiobuttontype1 extends RecyclerView.ViewHolder {
        ImageView clockout_imageradiobutton;
        RadioButton clockout_radiobutton;
        TextView sample;

        public radiobuttontype1(View itemView) {
            super(itemView);
            clockout_imageradiobutton = (ImageView) itemView.findViewById(R.id.clockout_imageradiobutton);
            clockout_radiobutton = (RadioButton) itemView.findViewById(R.id.clockout_radiobutton);
            sample = (TextView) itemView.findViewById(R.id.sample);
        }
    }

    public MultiViewTypeAdapter(ArrayList<QueDatum> data, Context context) {
        this.dataSet = data;
        this.mContext = context;
    }

    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {
        if (viewType.equalsIgnoreCase("1")) {
            View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.clockout_radio_list_row, viewGroup, false);
            return new radiobuttontype1(view);

        } else if (viewType.equalsIgnoreCase("2")) {
            View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.clockout_cbox_list_row, viewGroup, false);
            view.setHorizontalFadingEdgeEnabled(true);
            return new Checkboxtype2(view);

        } else if (viewType.equalsIgnoreCase("3")) {
            View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.clockout_radio_list_row, viewGroup, false);
            return new Radiobuttontype1(view);

        } else if (viewType.equalsIgnoreCase("4")) {
            View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.clockout_radio_list_row, viewGroup, false);
            return new Radiobuttontype1(view);

        } else if (viewType.equalsIgnoreCase("5")) {
            View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.clockout_radio_list_row, viewGroup, false);
            return new Radiobuttontype1(view);
        }

        return null;
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder viewHolder, int viewType) {
        if (viewType.equalsIgnoreCase("1")) {
            options =  dataSet.get(i).getOptions();
            question = dataSet.get(i).getQuestion();
            image = options.get(i).getValue();
            ((radiobuttontype1) viewHolder).clockout_radiobutton.setChecked(false);
            ((radiobuttontype1) viewHolder).sample.setText(question);
            //Loading image bitmap in the ViewHolder's View
            Picasso.with(mContext)
                    .load(image)
                    .into(((radiobuttontype1) viewHolder).clockout_imageradiobutton);

        } else if (viewType.equalsIgnoreCase("2")) {
            options = (ArrayList<Clockout_questions_Option>) dataSet.get(i).getOptions();
            question = dataSet.get(i).getQuestion();
            image = options.get(i).getValue();
            //Loading image bitmap in the ViewHolder's View
            Picasso.with(mContext)
                    .load(image)
                    .into(((Checkboxtype2) viewHolder).imgclockcheck);

        } else if (viewType.equalsIgnoreCase("3")) {
            //Fit data to viewHolder for ViewType 3
        } else if (viewType.equalsIgnoreCase("4")) {
            //Fit data to viewHolder for ViewType 4
        } else if (viewType.equalsIgnoreCase("5")) {
            //Fit data to viewHolder for ViewType 5
        }
    }

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

    /**
     * Returns viewType for that position by picking the viewType value from the
     *     dataset
     */
    @Override
    public int getItemViewType(int position) {
        return dataSet.get(position).getViewType();
    }
}

你可以避免在onBindViewHolder()中基于多个条件的viewHolder数据填充,通过为不同位置的viewHolder中相似的视图分配相同的id。

为不同的布局创建不同的ViewHolder

RecyclerView可以有任意数量的viewholders,但为了更好的可读性,让我们看看如何创建一个有两个viewholders的viewholders。

这可以通过三个简单的步骤来完成

覆盖公共int getItemViewType(int position) 在onCreateViewHolder()方法中根据ViewType返回不同的ViewHolders 根据onBindViewHolder()方法中的itemViewType填充视图

下面是一小段代码片段:

public class YourListAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

   private static final int LAYOUT_ONE = 0;
   private static final int LAYOUT_TWO = 1;

   @Override
   public int getItemViewType(int position)
   {
      if(position==0)
        return LAYOUT_ONE;
      else
        return LAYOUT_TWO;
   }

   @Override
   public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

      View view = null;
      RecyclerView.ViewHolder viewHolder = null;

      if(viewType==LAYOUT_ONE)
      {
          view = LayoutInflater.from(parent.getContext()).inflate(R.layout.one,parent,false);
          viewHolder = new ViewHolderOne(view);
      }
      else
      {
          view = LayoutInflater.from(parent.getContext()).inflate(R.layout.two,parent,false);
          viewHolder= new ViewHolderTwo(view);
      }

      return viewHolder;
   }

   @Override
   public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) {

      if(holder.getItemViewType() == LAYOUT_ONE)
      {
            // Typecast Viewholder
            // Set Viewholder properties
            // Add any click listener if any
      }
      else {
        ViewHolderOne vaultItemHolder = (ViewHolderOne) holder;
        vaultItemHolder.name.setText(displayText);
        vaultItemHolder.name.setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View v) {
            .......
           }
         });
       }
   }

  //****************  VIEW HOLDER 1 ******************//

   public class ViewHolderOne extends RecyclerView.ViewHolder {

      public TextView name;

      public ViewHolderOne(View itemView) {
         super(itemView);
         name = (TextView)itemView.findViewById(R.id.displayName);
     }
   }


   //****************  VIEW HOLDER 2 ******************//

   public class ViewHolderTwo extends RecyclerView.ViewHolder {

      public ViewHolderTwo(View itemView) {
         super(itemView);

        ..... Do something
      }
   }
}

getItemViewType(int position)是键。

在我看来,创建这种recyclerView的起点是这个方法的知识。因为这个方法是可选的,所以默认情况下它在RecylerView类中是不可见的,这使得许多开发人员(包括我)不知道从哪里开始。

一旦您知道了这个方法的存在,创建这样的RecyclerView将是小菜一菜。

让我们看一个例子来证明我的观点。如果你想显示两个布局 在交替的位置上这样做

@Override
public int getItemViewType(int position)
{
   if(position%2==0)       // Even position
     return LAYOUT_ONE;
   else                   // Odd position
     return LAYOUT_TWO;
}

相关链接:

看看我已经实现了这个项目。

比以往任何时候都简单,忘记ViewTypes。不建议在一个适配器中使用多个视图类型。这将使代码混乱,并打破单一责任原则,因为现在适配器需要处理逻辑来知道要填充哪个视图。

现在,想象一下在大型团队中工作,每个团队都必须在这些视图类型中的一种功能中工作。如果在不同视图类型中工作的所有团队都使用同一个适配器,那将是一团糟。这是使用ConcatAdapter解决的,其中隔离了适配器。逐个编码,然后将它们合并到一个视图中。

在recyclerview:1.2.0-alpha04中,您现在可以使用ConcatAdapter。

如果你需要一个具有不同viewTypes的视图,你可以为每个部分编写适配器,并使用ConcatAdapter将它们合并到一个recyclerview中。

ConcatAdapter

这张图片显示了一个recyclerview拥有的三种不同的视图类型,页眉,内容和页脚。

你只需要为每个section创建一个适配器,然后使用ConcatAdapter将它们合并到一个recyclerview中:

val firstAdapter: FirstAdapter = …
val secondAdapter: SecondAdapter = …
val thirdAdapter: ThirdAdapter = …
val concatAdapter = ConcatAdapter(firstAdapter, secondAdapter,
                                  thirdAdapter)
recyclerView.adapter = concatAdapter

这就是你需要知道的。如果您想处理加载状态,例如在某些加载发生后删除最后一个适配器,您可以使用LoadState。

欲了解更多深入信息,请关注Florina Muntenescu的帖子https://medium.com/androiddevelopers/merge-adapters-sequentially-with-mergeadapter-294d2942127a

遵循Anton的解决方案,我想出了这个ViewHolder,它持有/处理/委托不同类型的布局。

但是我不确定当回收视图的ViewHolder不是数据滚入的类型时,替换新的布局是否会工作。

所以基本上, onCreateViewHolder(ViewGroup父视图,int viewType)只在需要新的视图布局时调用;

getItemViewType(int position)将为viewType调用;

onBindViewHolder(ViewHolder holder, int position)总是在回收视图时被调用(新数据被引入并尝试与ViewHolder一起显示)。

当onBindViewHolder被调用时,它需要被放在正确的视图布局中并更新ViewHolder。

public int getItemViewType(int position) {
    TypedData data = mDataSource.get(position);
    return data.type;
}

public ViewHolder onCreateViewHolder(ViewGroup parent,
    int viewType) {
    return ViewHolder.makeViewHolder(parent, viewType);
}

public void onBindViewHolder(ViewHolder holder,
    int position) {
    TypedData data = mDataSource.get(position);
    holder.updateData(data);
}

///
public static class ViewHolder extends
    RecyclerView.ViewHolder {

    ViewGroup mParentViewGroup;
    View mCurrentViewThisViewHolderIsFor;
    int mDataType;

    public TypeOneViewHolder mTypeOneViewHolder;
    public TypeTwoViewHolder mTypeTwoViewHolder;

    static ViewHolder makeViewHolder(ViewGroup vwGrp,
        int dataType) {
        View v = getLayoutView(vwGrp, dataType);
        return new ViewHolder(vwGrp, v, viewType);
    }

    static View getLayoutView(ViewGroup vwGrp,
        int dataType) {
        int layoutId = getLayoutId(dataType);
        return LayoutInflater.from(vwGrp.getContext())
                             .inflate(layoutId, null);
    }

    static int getLayoutId(int dataType) {
        if (dataType == TYPE_ONE) {
            return R.layout.type_one_layout;
        } else if (dataType == TYPE_TWO) {
            return R.layout.type_two_layout;
        }
    }

    public ViewHolder(ViewGroup vwGrp, View v,
        int dataType) {
        super(v);
        mDataType = dataType;
        mParentViewGroup = vwGrp;
        mCurrentViewThisViewHolderIsFor = v;

        if (data.type == TYPE_ONE) {
            mTypeOneViewHolder = new TypeOneViewHolder(v);
        } else if (data.type == TYPE_TWO) {
            mTypeTwoViewHolder = new TypeTwoViewHolder(v);
        }
    }

    public void updateData(TypeData data) {
        mDataType = data.type;
        if (data.type == TYPE_ONE) {
            mTypeTwoViewHolder = null;
            if (mTypeOneViewHolder == null) {
                View newView = getLayoutView(mParentViewGroup,
                               data.type);

                /**
                 *  How can I replace a new view with
                    the view in the parent
                    view container?
                 */
                replaceView(mCurrentViewThisViewHolderIsFor,
                            newView);
                mCurrentViewThisViewHolderIsFor = newView;

                mTypeOneViewHolder =
                    new TypeOneViewHolder(newView);
            }
            mTypeOneViewHolder.updateDataTypeOne(data);

        } else if (data.type == TYPE_TWO){
            mTypeOneViewHolder = null;
            if (mTypeTwoViewHolder == null) {
                View newView = getLayoutView(mParentViewGroup,
                               data.type);

                /**
                 *  How can I replace a new view with
                    the view in the parent view
                    container?
                 */
                replaceView(mCurrentViewThisViewHolderIsFor,
                            newView);
                mCurrentViewThisViewHolderIsFor = newView;

                mTypeTwoViewHolder =
                    new TypeTwoViewHolder(newView);
            }
            mTypeTwoViewHolder.updateDataTypeOne(data);
        }
    }
}

public static void replaceView(View currentView,
    View newView) {
    ViewGroup parent = (ViewGroup)currentView.getParent();
    if(parent == null) {
        return;
    }
    final int index = parent.indexOfChild(currentView);
    parent.removeView(currentView);
    parent.addView(newView, index);
}

ViewHolder有成员mItemViewType来保存视图。

它看起来像在onBindViewHolder(ViewHolder holder, int position)中传递进来的ViewHolder已经通过查看getItemViewType(int position)来获取(或创建),以确保它是匹配的,所以它可能不需要担心ViewHolder的类型不匹配数据[position]的类型。

看起来循环ViewHolder是由类型选择的,所以这里没有战士。

构建一个RecyclerView LayoutManager -第1部分回答了这个问题。

它像这样得到循环ViewHolder:

holder = getRecycledViewPool().getRecycledView(mAdapter.getItemViewType(offsetPosition));

如果没有找到正确类型的recycle ViewHolder,也可以创建一个新的。

public ViewHolder getRecycledView(int viewType) {
        final ArrayList<ViewHolder> scrapHeap = mScrap.get(viewType);
        if (scrapHeap != null && !scrapHeap.isEmpty()) {
            final int index = scrapHeap.size() - 1;
            final ViewHolder scrap = scrapHeap.get(index);
            scrapHeap.remove(index);
            return scrap;
        }
        return null;
    }

View getViewForPosition(int position, boolean dryRun) {
    ......

    if (holder == null) {
            final int offsetPosition = mAdapterHelper.findPositionOffset(position);
            if (offsetPosition < 0 || offsetPosition >= mAdapter.getItemCount()) {
                throw new IndexOutOfBoundsException("Inconsistency detected. Invalid item "
                        + "position " + position + "(offset:" + offsetPosition + ")."
                        + "state:" + mState.getItemCount());
            }

            final int type = mAdapter.getItemViewType(offsetPosition);
            // 2) Find from scrap via stable ids, if exists
            if (mAdapter.hasStableIds()) {
                holder = getScrapViewForId(mAdapter.getItemId(offsetPosition), type, dryRun);
                if (holder != null) {
                    // update position
                    holder.mPosition = offsetPosition;
                    fromScrap = true;
                }
            }
            if (holder == null && mViewCacheExtension != null) {
                // We are NOT sending the offsetPosition because LayoutManager does not
                // know it.
                final View view = mViewCacheExtension
                        .getViewForPositionAndType(this, position, type);
                if (view != null) {
                    holder = getChildViewHolder(view);
                    if (holder == null) {
                        throw new IllegalArgumentException("getViewForPositionAndType returned"
                                + " a view which does not have a ViewHolder");
                    } else if (holder.shouldIgnore()) {
                        throw new IllegalArgumentException("getViewForPositionAndType returned"
                                + " a view that is ignored. You must call stopIgnoring before"
                                + " returning this view.");
                    }
                }
            }
            if (holder == null) { // fallback to recycler
                // try recycler.
                // Head to the shared pool.
                if (DEBUG) {
                    Log.d(TAG, "getViewForPosition(" + position + ") fetching from shared "
                            + "pool");
                }
                holder = getRecycledViewPool()
                        .getRecycledView(mAdapter.getItemViewType(offsetPosition));
                if (holder != null) {
                    holder.resetInternal();
                    if (FORCE_INVALIDATE_DISPLAY_LIST) {
                        invalidateDisplayListInt(holder);
                    }
                }
            }
            if (holder == null) {
                holder = mAdapter.createViewHolder(RecyclerView.this,
                        mAdapter.getItemViewType(offsetPosition));
                if (DEBUG) {
                    Log.d(TAG, "getViewForPosition created new ViewHolder");
                }
            }
        }
        boolean bound = false;
        if (mState.isPreLayout() && holder.isBound()) {
            // do not update unless we absolutely have to.
            holder.mPreLayoutPosition = position;
        } else if (!holder.isBound() || holder.needsUpdate() || holder.isInvalid()) {
            if (DEBUG && holder.isRemoved()) {
                throw new IllegalStateException("Removed holder should be bound and it should"
                        + " come here only in pre-layout. Holder: " + holder);
            }
            final int offsetPosition = mAdapterHelper.findPositionOffset(position);
            mAdapter.bindViewHolder(holder, offsetPosition);
            attachAccessibilityDelegate(holder.itemView);
            bound = true;
            if (mState.isPreLayout()) {
                holder.mPreLayoutPosition = position;
            }
        }

        final ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams();
        final LayoutParams rvLayoutParams;
        if (lp == null) {
            rvLayoutParams = (LayoutParams) generateDefaultLayoutParams();
            holder.itemView.setLayoutParams(rvLayoutParams);
        } else if (!checkLayoutParams(lp)) {
            rvLayoutParams = (LayoutParams) generateLayoutParams(lp);
            holder.itemView.setLayoutParams(rvLayoutParams);
        } else {
            rvLayoutParams = (LayoutParams) lp;
        }
        rvLayoutParams.mViewHolder = holder;
        rvLayoutParams.mPendingInvalidate = fromScrap && bound;
        return holder.itemView;
}

是的,这是可能的。

在您的适配器getItemViewType布局如下....

public class MultiViewTypeAdapter extends RecyclerView.Adapter {

    private ArrayList<Model>dataSet;
    Context mContext;
    int total_types;
    MediaPlayer mPlayer;
    private boolean fabStateVolume = false;

    public static class TextTypeViewHolder extends RecyclerView.ViewHolder {

        TextView txtType;
        CardView cardView;

        public TextTypeViewHolder(View itemView) {
            super(itemView);

            this.txtType = (TextView) itemView.findViewById(R.id.type);
            this.cardView = (CardView) itemView.findViewById(R.id.card_view);
        }
    }

    public static class ImageTypeViewHolder extends RecyclerView.ViewHolder {

        TextView txtType;
        ImageView image;

        public ImageTypeViewHolder(View itemView) {
            super(itemView);

            this.txtType = (TextView) itemView.findViewById(R.id.type);
            this.image = (ImageView) itemView.findViewById(R.id.background);
        }
    }

    public static class AudioTypeViewHolder extends RecyclerView.ViewHolder {

        TextView txtType;
        FloatingActionButton fab;

        public AudioTypeViewHolder(View itemView) {
            super(itemView);

            this.txtType = (TextView) itemView.findViewById(R.id.type);
            this.fab = (FloatingActionButton) itemView.findViewById(R.id.fab);
        }
    }

    public MultiViewTypeAdapter(ArrayList<Model>data, Context context) {
        this.dataSet = data;
        this.mContext = context;
        total_types = dataSet.size();
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        View view;
        switch (viewType) {
            case Model.TEXT_TYPE:
                view = LayoutInflater.from(parent.getContext()).inflate(R.layout.text_type, parent, false);
                return new TextTypeViewHolder(view);
            case Model.IMAGE_TYPE:
                view = LayoutInflater.from(parent.getContext()).inflate(R.layout.image_type, parent, false);
                return new ImageTypeViewHolder(view);
            case Model.AUDIO_TYPE:
                view = LayoutInflater.from(parent.getContext()).inflate(R.layout.audio_type, parent, false);
                return new AudioTypeViewHolder(view);
        }
        return null;
    }

    @Override
    public int getItemViewType(int position) {

        switch (dataSet.get(position).type) {
            case 0:
                return Model.TEXT_TYPE;
            case 1:
                return Model.IMAGE_TYPE;
            case 2:
                return Model.AUDIO_TYPE;
            default:
                return -1;
        }
    }

    @Override
    public void onBindViewHolder(final RecyclerView.ViewHolder holder, final int listPosition) {

        Model object = dataSet.get(listPosition);
        if (object != null) {
            switch (object.type) {
                case Model.TEXT_TYPE:
                    ((TextTypeViewHolder) holder).txtType.setText(object.text);

                    break;
                case Model.IMAGE_TYPE:
                    ((ImageTypeViewHolder) holder).txtType.setText(object.text);
                    ((ImageTypeViewHolder) holder).image.setImageResource(object.data);
                    break;
                case Model.AUDIO_TYPE:

                    ((AudioTypeViewHolder) holder).txtType.setText(object.text);

            }
        }
    }

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

Android RecyclerView示例-多个视图类型