我正在寻找一个相当于addHeaderView回收视图。基本上我想有2个按钮的图像被添加到列表视图的标题。有不同的方法来添加一个头视图到回收视图吗?举个例子作为指导会很有帮助

编辑2(增加片段布局):

在添加日志语句之后,getViewType似乎只接收到0的位置。这导致onCreateView只加载一个布局:

10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> getItemCount: 5
10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> getItemCount: 5
10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> getItemCount: 5
10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> getItemCount: 5
10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> getItemCount: 5
10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> getItemCount: 5
10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> getItemCount: 5
10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> getItemCount: 5
10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> getItemCount: 5
10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> getItemCount: 5
10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> getItemCount: 5
10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> getItemViewType position: 0
10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> getItemViewType position: 0
10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> getItemViewType position: 0
10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> onCreateViewHolder, viewtype: 0
10-26 16:32:53.766    5449-5449/co.testapp I/logger info﹕ Adapter-> onBindViewHolder, viewType: 0

片段转换来加载CommentFragment:

@Override
public void onPhotoFeedItemClick(View view, int position) {
    if (fragmentManager == null)
        fragmentManager = getSupportFragmentManager();

FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

    if (view.getId() == R.id.button_comment){
        CommentFragment commentFragment = CommentFragment.newInstance("","", position);
        fragmentTransaction.add(R.id.main_activity, commentFragment,"comment_fragment_tag");
        fragmentTransaction.addToBackStack(Constants.TAG_COMMENTS);
        fragmentTransaction.commit();
    }
}

Fragment的onCreateView:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.fragment_comment, container, false);
    mRecyclerView = (RecyclerView) view.findViewById(R.id.list_recylclerview);
    mRecyclerView.setLayoutManager(new LinearLayoutManager(_context));
    mRecyclerView.setItemAnimator(new DefaultItemAnimator());
    mAdapter = new CommentAdapter(R.layout.row_list_comments, R.layout.row_header_comments, _context, comments);
    mRecyclerView.setAdapter(mAdapter);
    return view;
}

包含recycleview的片段:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    tools:context="co.testapp.fragments.CommentFragment"
    android:background="@color/white">
        <RelativeLayout
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:orientation="vertical">
            <android.support.v7.widget.RecyclerView
                xmlns:android="http://schemas.android.com/apk/res/android"
                android:id="@+id/list_recylclerview"
                android:layout_width="match_parent"
                android:layout_height="200dp" />
        </RelativeLayout>
</RelativeLayout>

注释行布局:

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent" android:layout_margin="10dp"
    android:background="@color/white">
    <!--Profile Picture-->
    <ImageView
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:id="@+id/profile_picture"
        android:background="@color/blue_testapp"/>
    <!--Name-->
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:text="First Name Last Name"
        android:textSize="16dp"
        android:textColor="@color/blue_testapp"
        android:id="@+id/name_of_poster"
        android:layout_toRightOf="@id/profile_picture"
        />
    <!--Comment-->
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:layout_marginTop="-5dp"
        android:text="This is a test comment"
        android:textSize="14dp"
        android:textColor="@color/black"
        android:id="@+id/comment"
        android:layout_below="@id/name_of_poster"
        android:layout_toRightOf="@id/profile_picture"/>
</RelativeLayout>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="match_parent">
    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="300dp"
        android:id="@+id/header_photo"
        android:layout_gravity="center_horizontal"/>
</LinearLayout>

适配器代码(感谢hister让我开始):

public class CommentAdapter extends RecyclerView.Adapter<ViewHolder>{

    private final int rowCardLayout;
    public static Context mContext;
    private final int headerLayout;
    private final String [] comments;
    private static final int HEADER = 0;
    private static final int OTHER = 1;

    public CommentAdapter(int rowCardLayout, int headerLayout, Context context, String [] comments) {
        this.rowCardLayout = rowCardLayout;
        this.mContext = context;
        this.comments = comments;
        this.headerLayout = headerLayout;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
        logger.i("onCreateViewHolder, viewtype: " + i); //viewtype always returns 0 so OTHER layout is never inflated
        if (i == HEADER) {
            View v = LayoutInflater.from(viewGroup.getContext()).inflate(headerLayout, viewGroup, false);
            return new ViewHolderHeader(v);
        }
        else if (i == OTHER){
            View v = LayoutInflater.from(viewGroup.getContext()).inflate(rowCardLayout, viewGroup, false);
            return new ViewHolderComments(v);
        }
        else 
          throw new RuntimeException("Could not inflate layout");
    }

    @Override
    public void onBindViewHolder(ViewHolder viewHolder, int i) {
        logger.i("onBindViewHolder, viewType: " + i);

        if (viewHolder instanceof ViewHolderComments)
            ((ViewHolderComments) viewHolder).comment.setText(comments[i].toString());
        if (viewHolder instanceof ViewHolderHeader)
           ((ViewHolderHeader) viewHolder).header.setImageResource(R.drawable.image2);
        else {
            logger.e("no instance of viewholder found");
        }
    }

    @Override
    public int getItemCount() {
        int count = comments.length + 1;
        logger.i("getItemCount: " + count);
        return count;
    }

    @Override
    public int getItemViewType(int position) {
        logger.i("getItemViewType position: " + position);
        if (position == HEADER)
            return HEADER;
        else
            return OTHER;
    }

    public static class ViewHolderComments extends RecyclerView.ViewHolder {
        public TextView comment;
        public ImageView image;

        public ViewHolderComments(View itemView) {
            super(itemView);
            comment = (TextView) itemView.findViewById(R.id.comment);
            image = (ImageView) itemView.findViewById(R.id.image);
        }
    }

    public static class ViewHolderHeader extends RecyclerView.ViewHolder {
        public final ImageView header;

        public ViewHolderHeader(View itemView){
            super(itemView);
            header = (ImageView) itemView.findViewById(R.id.header_photo);
        }
    }
}

使用上面的代码,只有头部布局显示为viewType总是0。它是这样的。如果我强制另一个布局,它看起来像这样:


当前回答

出于个人目的,我在@hister的基础上做了一个实现,但使用了继承。

我在抽象超类HeadingableRecycleAdapter中隐藏了实现细节机制(如向itemCount中添加1,从position中减去1),通过 实现所需的方法从适配器像onBindViewHolder, getItemViewType和getItemCount,使该方法最终,并提供新的方法与隐藏的逻辑客户端:

onAddViewHolder (RecyclerView。ViewHolder holder, int position), onCreateViewHolder (ViewGroup父), itemCount ()

这里是HeadingableRecycleAdapter类和一个客户端。我留下的标题布局有点硬编码,因为它符合我的需要。

public abstract class HeadingableRecycleAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

    private static final int HEADER_VIEW_TYPE = 0;

    @LayoutRes
    private int headerLayoutResource;
    private String headerTitle;
    private Context context;

    public HeadingableRecycleAdapter(@LayoutRes int headerLayoutResourceId, String headerTitle, Context context) {
        this.headerLayoutResource = headerLayoutResourceId;
        this.headerTitle = headerTitle;
        this.context = context;
    }

    public Context context() {
        return context;
    }

    @Override
    public final RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        if (viewType == HEADER_VIEW_TYPE) {
            return new HeaderViewHolder(LayoutInflater.from(context).inflate(headerLayoutResource, parent, false));
        }
        return onCreateViewHolder(parent);
    }

    @Override
    public final void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        int viewType = getItemViewType(position);
        if (viewType == HEADER_VIEW_TYPE) {
            HeaderViewHolder vh = (HeaderViewHolder) holder;
            vh.bind(headerTitle);
        } else {
            onAddViewHolder(holder, position - 1);
        }
    }

    @Override
    public final int getItemViewType(int position) {
        return position == 0 ? 0 : 1;
    }

    @Override
    public final int getItemCount() {
        return itemCount() + 1;
    }

    public abstract int itemCount();

    public abstract RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent);

    public abstract void onAddViewHolder(RecyclerView.ViewHolder holder, int position);

}



@PerActivity
public class IngredientsAdapter extends HeadingableRecycleAdapter {
    public static final String TITLE = "Ingredients";
    private List<Ingredient> itemList;


    @Inject
    public IngredientsAdapter(Context context) {
        super(R.layout.layout_generic_recyclerview_cardified_header, TITLE, context);
    }

    public void setItemList(List<Ingredient> itemList) {
        this.itemList = itemList;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent) {
        return new ViewHolder(LayoutInflater.from(context()).inflate(R.layout.item_ingredient, parent, false));
    }

    @Override
    public void onAddViewHolder(RecyclerView.ViewHolder holder, int position) {
        ViewHolder vh = (ViewHolder) holder;
        vh.bind(itemList.get(position));
    }

    @Override
    public int itemCount() {
        return itemList == null ? 0 : itemList.size();
    }

    private String getQuantityFormated(double quantity, String measure) {
        if (quantity == (long) quantity) {
            return String.format(Locale.US, "%s %s", String.valueOf(quantity), measure);
        } else {
            return String.format(Locale.US, "%.1f %s", quantity, measure);
        }
    }


    class ViewHolder extends RecyclerView.ViewHolder {
        @BindView(R.id.text_ingredient)
        TextView txtIngredient;

        ViewHolder(View itemView) {
            super(itemView);
            ButterKnife.bind(this, itemView);
        }

        void bind(Ingredient ingredient) {
            String ingredientText = ingredient.getIngredient();
            txtIngredient.setText(String.format(Locale.US, "%s %s ", getQuantityFormated(ingredient.getQuantity(),
                    ingredient.getMeasure()), Character.toUpperCase(ingredientText.charAt(0)) +
                    ingredientText
                            .substring(1)));
        }
    }
}

其他回答

我知道这是一个老问题,但我还是想提供一个答案。

这里有一个ConcatAdapter(文档)可以为您解决这个问题。 你所要做的就是定义你的头视图布局,并用一个项目创建一个虚拟适配器 在Kotlin中,它只需要几行

class HeaderAdapter(private val inflater: LayoutInflater) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
    
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) = object : RecyclerView.ViewHolder(inflater.inflate(yourViewLayoutId, parent, false)) {}

    override fun onBindViewHolder(viewHolder: RecyclerView.ViewHolder, position: Int) {}

    override fun getItemCount() = 1
}

在此之后,您所要做的就是将头适配器和原始适配器添加到ConcatAdapter

recyclerView.adapter = ConcatAdapter(headerAdapter, adapter)

有关更多详细信息和高级案例,请参阅文档。

已经过去几年了,但以防有人以后读到这篇文章……

使用上面的代码,只有头部布局显示为viewType总是0。

问题在于常量声明:

private static final int HEADER = 0;
private static final int OTHER = 0;  <== bug 

如果您将它们都声明为零,那么您将始终得到零!

如果您想在多个列表之间轻松重用头文件,请查看recyclerview库的1.2.0版本。它引入了ConcatAdapter类,该类将多个适配器连接成一个适配器。因此,你可以创建一个头适配器,并轻松地将它与任何其他适配器结合起来,比如:

myRecyclerView.adapter = ConcatAdapter(headerAdapter, listAdapter)

公告文章包含了如何使用ConcatAdapter在页眉和页脚中显示加载进度的示例。

当我发布这个答案的时候,这个库的1.2.0版本还在alpha阶段,所以api可能会改变。您可以在这里查看状态。

基于这篇文章,我创建了一个RecyclerView的子类。支持任意数量的页眉和页脚的适配器。

https://gist.github.com/mheras/0908873267def75dc746

虽然这似乎是一个解决方案,但我也认为这个东西应该由LayoutManager管理。不幸的是,我现在需要它,我没有时间从头开始实现StaggeredGridLayoutManager(甚至也没有从它扩展)。

我还在测试,但如果你想试试也可以。如果你发现有任何问题,请告诉我。

简单和可重复使用的物品装饰

静态标题可以很容易地使用ItemDecoration添加,而不需要任何进一步的更改。

// add the decoration. done.
HeaderDecoration headerDecoration = new HeaderDecoration(/* init */);
recyclerView.addItemDecoration(headerDecoration);

装饰也是可重用的,因为根本不需要修改适配器或RecyclerView。

下面提供的示例代码将需要在顶部添加一个视图,该视图可以像其他任何东西一样膨胀。它可以是这样的:

为什么是静态的?

如果你只是要显示文本和图像,这个解决方案是为你-不可能的用户交互,如按钮或查看分页,因为它只会被绘制到列表的顶部。

空列表处理

如果没有视图来装饰,装饰就画不出来了。您仍然需要自己处理一个空列表。(一种可行的解决方法是向适配器添加一个虚拟项。)

的代码

你可以在GitHub上找到完整的源代码,包括一个Builder来帮助初始化装饰器,或者只是使用下面的代码并将自己的值提供给构造函数。

请确保为您的视图设置正确的layout_height。例如,match_parent可能无法正常工作。

public class HeaderDecoration extends RecyclerView.ItemDecoration {

    private final View mView;
    private final boolean mHorizontal;
    private final float mParallax;
    private final float mShadowSize;
    private final int mColumns;
    private final Paint mShadowPaint;

    public HeaderDecoration(View view, boolean scrollsHorizontally, float parallax, float shadowSize, int columns) {
        mView = view;
        mHorizontal = scrollsHorizontally;
        mParallax = parallax;
        mShadowSize = shadowSize;
        mColumns = columns;

        if (mShadowSize > 0) {
            mShadowPaint = new Paint();
            mShadowPaint.setShader(mHorizontal ?
                    new LinearGradient(mShadowSize, 0, 0, 0,
                            new int[]{Color.argb(55, 0, 0, 0), Color.argb(55, 0, 0, 0), Color.argb(3, 0, 0, 0)},
                            new float[]{0f, .5f, 1f},
                            Shader.TileMode.CLAMP) :
                    new LinearGradient(0, mShadowSize, 0, 0,
                            new int[]{Color.argb(55, 0, 0, 0), Color.argb(55, 0, 0, 0), Color.argb(3, 0, 0, 0)},
                            new float[]{0f, .5f, 1f},
                            Shader.TileMode.CLAMP));
        } else {
            mShadowPaint = null;
        }
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        super.onDraw(c, parent, state);
        // layout basically just gets drawn on the reserved space on top of the first view
        mView.layout(parent.getLeft(), 0, parent.getRight(), mView.getMeasuredHeight());

        for (int i = 0; i < parent.getChildCount(); i++) {
            View view = parent.getChildAt(i);
            if (parent.getChildAdapterPosition(view) == 0) {
                c.save();
                if (mHorizontal) {
                    c.clipRect(parent.getLeft(), parent.getTop(), view.getLeft(), parent.getBottom());
                    final int width = mView.getMeasuredWidth();
                    final float left = (view.getLeft() - width) * mParallax;
                    c.translate(left, 0);
                    mView.draw(c);
                    if (mShadowSize > 0) {
                        c.translate(view.getLeft() - left - mShadowSize, 0);
                        c.drawRect(parent.getLeft(), parent.getTop(), mShadowSize, parent.getBottom(), mShadowPaint);
                    }
                } else {
                    c.clipRect(parent.getLeft(), parent.getTop(), parent.getRight(), view.getTop());
                    final int height = mView.getMeasuredHeight();
                    final float top = (view.getTop() - height) * mParallax;
                    c.translate(0, top);
                    mView.draw(c);
                    if (mShadowSize > 0) {
                        c.translate(0, view.getTop() - top - mShadowSize);
                        c.drawRect(parent.getLeft(), parent.getTop(), parent.getRight(), mShadowSize, mShadowPaint);
                    }
                }
                c.restore();
                break;
            }
        }
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        if (parent.getChildAdapterPosition(view) < mColumns) {
            if (mHorizontal) {
                if (mView.getMeasuredWidth() <= 0) {
                    mView.measure(View.MeasureSpec.makeMeasureSpec(parent.getMeasuredWidth(), View.MeasureSpec.AT_MOST),
                            View.MeasureSpec.makeMeasureSpec(parent.getMeasuredHeight(), View.MeasureSpec.AT_MOST));
                }
                outRect.set(mView.getMeasuredWidth(), 0, 0, 0);
            } else {
                if (mView.getMeasuredHeight() <= 0) {
                    mView.measure(View.MeasureSpec.makeMeasureSpec(parent.getMeasuredWidth(), View.MeasureSpec.AT_MOST),
                            View.MeasureSpec.makeMeasureSpec(parent.getMeasuredHeight(), View.MeasureSpec.AT_MOST));
                }
                outRect.set(0, mView.getMeasuredHeight(), 0, 0);
            }
        } else {
            outRect.setEmpty();
        }
    }
}

请注意:GitHub项目是我个人的游乐场。它没有经过彻底的测试,这就是为什么还没有库。

它能做什么?

ItemDecoration是对列表项的附加绘图。在这种情况下,装饰被绘制到第一项的顶部。

视图被测量和布局,然后被绘制到第一个项目的顶部。如果添加视差效果,它也会被剪辑到正确的边界。