在RecyclerView中更改不同视图的布局管理器

Question

我实现了一个可扩展的recyclerview,其子元素是列表的一部分.我按照这个代码.这是它的工作原理,

使用RecyclerView实现ExpandableListView简要描述如下.列表模型有一个附加参数"type",用于标识项目是标题还是子项.通过检查此参数,适配器会扩展与该类型对应的视图和视图.如果类型是HEADER,它将膨胀标题项的布局,其中包含TextView和ImageView,用于指示子树是否展开.

现在,我想要做的是使扩展的布局成为网格.我通常会通过将布局管理器设置为GridLayoutManager来实现这一点,但在这种情况下,我只使用一个recyclerview,这意味着我无法在不更改标题的情况下更改布局管理器,最终导致整个recyclerview变为网格包括标题.

我的问题是:如何在适配器内仅为几个布局更改布局管理器？

编辑:我添加了一些代码.

Recyclerview适配器:

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

// These are constants that are used to determine if the item is a child or a header and is defined with each item from the data model
public static final int HEADER = 0;
public static final int CHILD = 1;

private List<Item> data;

public ExpandableListAdapter(List<Item> data) {
    this.data = data;
}

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int type) {
    View view = null;

    LayoutInflater inflater = (LayoutInflater) parent.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    // Check whether the item is a header or child and inflate differnet layouts
    switch (type) {
        case HEADER:
            // Inflate a header layout if the item is a header
            view = inflater.inflate(R.layout.list_header, parent, false);
            ListHeaderViewHolder header = new ListHeaderViewHolder(view);
            return header;
        case CHILD:
            // Inflate a child layout if the item is a child
            view = inflater.inflate(R.layout.list_child, parent, false);
            ListChildViewHolder child = new ListChildViewHolder(view);
            return child;
    }
    return null;
}

public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
    final Item item = data.get(position);

    // Bind different layouts based on if the item is a header or child
    switch (item.getType()) {
        case HEADER:
            // ...
        case CHILD:
            // ...
    }
}

@Override
public int getItemViewType(int position) {
    return data.get(position).type;
}

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

// Viewholder for the header items
private static class ListHeaderViewHolder extends RecyclerView.ViewHolder {
    // ...
}

// Viewholder for the child items
private static class ListChildViewHolder extends RecyclerView.ViewHolder {
    // ...
}

这是我声明布局管理器的主要活动:

recyclerview = (RecyclerView) findViewById(R.id.recyclerview);
recyclerview.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));

Answer 1

您可以将布局管理器更改为GridLayoutManager并定义标题的"跨度大小",例如,如果您希望网格具有2列,则标题应具有跨度大小2且子跨度大小为1:

    GridLayoutManager glm = new GridLayoutManager(getContext(), 2);
    glm.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
        @Override
        public int getSpanSize(int position) {
            switch(getTypeForPosition(position)) {
                case HEADER:
                    return 2;
                default:
                    return 1;
            }
        }
    });
    recyclerView.setLayoutManager(glm);

有一个与头部扩张电网的完整的例子在这里使用这个库.