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

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。

其他回答

使用Kotlin,视图类型的实现变得更加容易。下面是这个light库https://github.com/Link184/KidAdapter的示例

recyclerView.setUp {
    withViewType {
        withLayoutResId(R.layout.item_int)
        withItems(mutableListOf(1, 2, 3, 4, 5, 6))
        bind<Int> { // this - is adapter view hoder itemView, it - current item
            intName.text = it.toString()
        }
    }


    withViewType("SECOND_STRING_TAG") {
        withLayoutResId(R.layout.item_text)
        withItems(mutableListOf("eight", "nine", "ten", "eleven", "twelve"))
        bind<String> {
            stringName.text = it
        }
    }
}

是的,这是可能的。只需实现getItemViewType(),并照顾onCreateViewHolder()中的viewType参数。

所以你可以这样做:

public class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
    class ViewHolder0 extends RecyclerView.ViewHolder {
        ...
        public ViewHolder0(View itemView){
        ...
        }
    }

    class ViewHolder2 extends RecyclerView.ViewHolder {
        ...
        public ViewHolder2(View itemView){
        ...
    }

    @Override
    public int getItemViewType(int position) {
        // Just as an example, return 0 or 2 depending on position
        // Note that unlike in ListView adapters, types don't have to be contiguous
        return position % 2 * 2;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
         switch (viewType) {
             case 0: return new ViewHolder0(...);
             case 2: return new ViewHolder2(...);
             ...
         }
    }

    @Override
    public void onBindViewHolder(final RecyclerView.ViewHolder holder, final int position) {
        switch (holder.getItemViewType()) {
            case 0:
                ViewHolder0 viewHolder0 = (ViewHolder0)holder;
                ...
                break;

            case 2:
                ViewHolder2 viewHolder2 = (ViewHolder2)holder;
                ...
                break;
        }
    }
}

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

我首先推荐你阅读Hannes Dorfmann关于这个主题的优秀文章。

当一个新的视图类型出现时,你必须编辑适配器,你必须处理这么多乱七八糟的事情。您的适配器应该对扩展开放,但对修改关闭。

你可以看看这两个项目,他们可以给出如何在适配器中处理不同的ViewTypes的想法:

https://github.com/sockeqwe/AdapterDelegates https://github.com/ibrahimyilmaz/kiel

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。