Android可收缩伸展的Expandable分组RecyclerView

短命女 2023-10-17 18:55 10阅读 0赞

**Android可收缩伸展的Expandable分组RecyclerView**

Android上的可收缩伸展的Expandable RecyclerView第三方开源项目很多，但是在自己的项目引用了这些github上的类似项目后，发现问题和Bug很多，不稳定，无奈之下，自己在RecyclerView基础上写了一个相对稳定、可以收缩伸展Expandable分组RecyclerView。  
代码：

import android.graphics.Color;
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.support.v7.widget.LinearLayoutManager;
    import android.support.v7.widget.RecyclerView;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.TextView;
    
    import java.util.ArrayList;
    import java.util.Iterator;
    
    public class MainActivity extends AppCompatActivity {
        private RecyclerViewAdapter mAdapter;
    
        private final int GROUP = 0xf01;
        private final int CHILD = 0xf02;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            RecyclerView mRecyclerView = findViewById(R.id.recycler_view);
    
            LinearLayoutManager layoutManager = new LinearLayoutManager(this);
            layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
            mRecyclerView.setLayoutManager(layoutManager);
    
            ArrayList<Item> mItems = new ArrayList<>();
            mAdapter = new RecyclerViewAdapter(mItems);
            mRecyclerView.setAdapter(mAdapter);
    
            String[] groups = {"A", "B", "C", "D", "E", "F"};
    
            for (int i = 0; i < groups.length; i++) {
                GroupItem groupItem = new GroupItem();
                groupItem.id = i;
                groupItem.title = groups[i];
    
                int count = (int) (Math.random() * 10) % 5 + 1;
                for (int j = 0; j < count; j++) {
                    ChildItem childItem = new ChildItem();
                    childItem.id = j;
                    childItem.group = groupItem;
                    groupItem.addChild(childItem);
                }
    
                mAdapter.addGroup(groupItem);
            }
    
            mAdapter.expand(0);
        }
    
        public class RecyclerViewAdapter extends RecyclerView.Adapter<ItemVH> {
            private ArrayList<Item> items;
    
            public RecyclerViewAdapter(ArrayList<Item> items) {
                this.items = items;
            }
    
            public void addGroup(GroupItem groupItem) {
                items.add(groupItem);
            }
    
            @Override
            public ItemVH onCreateViewHolder(ViewGroup parent, int viewType) {
                View view;
                ItemVH itemVH = null;
                switch (viewType) {
                    case GROUP:
                        view = LayoutInflater.from(parent.getContext()).inflate(android.R.layout.simple_list_item_1, parent, false);
                        itemVH = new GroupVH(view);
                        break;
    
                    case CHILD:
                        view = LayoutInflater.from(parent.getContext()).inflate(android.R.layout.simple_list_item_1, parent, false);
                        itemVH = new ChildVH(view);
                        break;
                }
    
                return itemVH;
            }
    
            @Override
            public void onBindViewHolder(ItemVH holder, final int position) {
                int viewType = getItemViewType(position);
                Item item = items.get(position);
    
                switch (viewType) {
                    case GROUP:
                        final GroupItem groupItem = (GroupItem) item;
                        GroupVH groupVH = (GroupVH) holder;
                        groupVH.text1.setText(groupItem.title);
                        groupVH.itemView.setOnClickListener(new View.OnClickListener() {
                            @Override
                            public void onClick(View v) {
                                action(groupItem, position);
                            }
                        });
    
                        break;
    
                    case CHILD:
                        ChildItem childItem = (ChildItem) item;
                        ChildVH childVH = (ChildVH) holder;
                        childVH.text1.setText(childItem.id + "");
                        break;
                }
            }
    
            @Override
            public int getItemCount() {
                return items.size();
            }
    
            @Override
            public int getItemViewType(int position) {
                return items.get(position).type();
            }
    
            public void expand(int groupOrder) {
                for (int i = 0; i < items.size(); i++) {
                    Item item = items.get(i);
                    if (item.type() == GROUP) {
                        GroupItem groupItem = (GroupItem) item;
                        if (groupItem.id == groupOrder) {
                            items.addAll(i + 1, groupItem.children);
                            groupItem.isExpand = true;
                        }
                    }
                }
    
                mAdapter.notifyDataSetChanged();
            }
    
            private void action(GroupItem groupItem, int position) {
                groupItem.isExpand = !groupItem.isExpand;
    
                if (groupItem.isExpand) {
                    items.addAll(position + 1, groupItem.children);
                } else {
                    Iterator<Item> iterator = items.iterator();
                    while (iterator.hasNext()) {
                        Item it = iterator.next();
                        if (it.type() == CHILD) {
                            ChildItem cid = (ChildItem) it;
                            if (cid.group.id == groupItem.id)
                                iterator.remove();
                        }
                    }
                }
    
                mAdapter.notifyDataSetChanged();
            }
        }
    
        private abstract class Item {
            public int id;
    
            public abstract int type();
        }
    
        private abstract class ItemVH extends RecyclerView.ViewHolder {
    
            public ItemVH(View itemView) {
                super(itemView);
            }
    
            public abstract int type();
        }
    
        private class ChildItem extends Item {
            public GroupItem group;
    
            @Override
            public int type() {
                return CHILD;
            }
        }
    
        private class GroupItem extends Item {
            public String title;
    
            public boolean isExpand = false;
            public ArrayList<ChildItem> children;
    
            public GroupItem() {
                children = new ArrayList<>();
            }
    
            @Override
            public int type() {
                return GROUP;
            }
    
            public void addChild(ChildItem childItem) {
                children.add(childItem);
            }
        }
    
        private class ChildVH extends ItemVH {
            public TextView text1;
    
            public ChildVH(View itemView) {
                super(itemView);
                text1 = itemView.findViewById(android.R.id.text1);
                text1.setBackgroundColor(Color.LTGRAY);
            }
    
            @Override
            public int type() {
                return CHILD;
            }
        }
    
        private class GroupVH extends ItemVH {
            private TextView text1;
    
            public GroupVH(View itemView) {
                super(itemView);
                text1 = itemView.findViewById(android.R.id.text1);
                text1.setTextColor(Color.WHITE);
                itemView.setBackgroundColor(Color.RED);
            }
    
            @Override
            public int type() {
                return GROUP;
            }
        }
    }

运行结果：

![20180404105133691][]

启动后首先为用户伸展开第0组（即第一组）。在以上代码基础上，有兴趣的读者可以再次深度二次定制化开发，比如在group的组GroupVH上增加收缩伸展改变时候的指示箭头。

[20180404105133691]: https://img-blog.csdn.net/20180404105133691