在RecyclerView或Grouping Recyclerview项目中的组上划分元素，例如按日期

Question

我想将我的android RecyclerView项目与基于日期的标头分组，如下所示：

    1 week ago
    - item
    - item
    - item
    - item
    2 weeks ago
    - item
    - item
    - item

基于某种元素的事物或分组。

Answer 1

这是我在网上进行大量研究后得到的一个解决方案，该博客链接以及Kartikey
Kuswhaha也是
如此，所以这并不是我的全部功劳，但我只是想更加清楚一点。下面是代码：创建以下文件：
PojoOfJsonArray ， MainActivity ， ListItem ， GeneralItem ，
DateItem ， Adapter

PojoOfJsonArray .java-该 文件将表示您的POJO类或您在应用程序中进行的任何pojo，因此：

 public class PojoOfJsonArray  {

    public PojoOfJsonArray(String name, String date) {
        this.name = name;
        this.date = date;
    }

    private String name,date;


    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }
}

MainActivity .java这是您将用来实现recyclerview的活动：

public class MainActivity extends AppCompatActivity {
    private List<PojoOfJsonArray> myOptions = new ArrayList<>();
    List<ListItem> consolidatedList = new ArrayList<>();

    private RecyclerView mRecyclerView;
    private Adapter adapter;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mRecyclerView = (RecyclerView) findViewById(R.id.recyclerview);
        mRecyclerView.setHasFixedSize(true);

        myOptions.add(new PojoOfJsonArray("name 1", "2016-06-21"));
        myOptions.add(new PojoOfJsonArray("name 2", "2016-06-05"));
        myOptions.add(new PojoOfJsonArray("name 2", "2016-06-05"));
        myOptions.add(new PojoOfJsonArray("name 3", "2016-05-17"));
        myOptions.add(new PojoOfJsonArray("name 3", "2016-05-17"));
        myOptions.add(new PojoOfJsonArray("name 3", "2016-05-17"));
        myOptions.add(new PojoOfJsonArray("name 3", "2016-05-17"));
        myOptions.add(new PojoOfJsonArray("name 2", "2016-06-05"));
        myOptions.add(new PojoOfJsonArray("name 3", "2016-05-17"));

        HashMap<String, List<PojoOfJsonArray>> groupedHashMap = groupDataIntoHashMap(myOptions);


        for (String date : groupedHashMap.keySet()) {
            DateItem dateItem = new DateItem();
            dateItem.setDate(date);
            consolidatedList.add(dateItem);


            for (PojoOfJsonArray pojoOfJsonArray : groupedHashMap.get(date)) {
                GeneralItem generalItem = new GeneralItem();
                generalItem.setPojoOfJsonArray(pojoOfJsonArray);//setBookingDataTabs(bookingDataTabs);
                consolidatedList.add(generalItem);
            }
        }


        adapter = new Adapter(this, consolidatedList);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
        mRecyclerView.setLayoutManager(layoutManager);
        mRecyclerView.setAdapter(adapter);


    }

    private HashMap<String, List<PojoOfJsonArray>> groupDataIntoHashMap(List<PojoOfJsonArray> listOfPojosOfJsonArray) {

        HashMap<String, List<PojoOfJsonArray>> groupedHashMap = new HashMap<>();

        for (PojoOfJsonArray pojoOfJsonArray : listOfPojosOfJsonArray) {

            String hashMapKey = pojoOfJsonArray.getDate();

            if (groupedHashMap.containsKey(hashMapKey)) {
                // The key is already in the HashMap; add the pojo object
                // against the existing key.
                groupedHashMap.get(hashMapKey).add(pojoOfJsonArray);
            } else {
                // The key is not there in the HashMap; create a new key-value pair
                List<PojoOfJsonArray> list = new ArrayList<>();
                list.add(pojoOfJsonArray);
                groupedHashMap.put(hashMapKey, list);
            }
        }


        return groupedHashMap;
    }

}

myOptions是用于将数据馈入其中的位置。 ListItem .java

public abstract class ListItem {

    public static final int TYPE_DATE = 0;
    public static final int TYPE_GENERAL = 1;

    abstract public int getType();
}

GeneralItem .java

public class GeneralItem extends ListItem {
    private PojoOfJsonArray pojoOfJsonArray;

    public PojoOfJsonArray getPojoOfJsonArray() {
        return pojoOfJsonArray;
    }

    public void setPojoOfJsonArray(PojoOfJsonArray pojoOfJsonArray) {
        this.pojoOfJsonArray = pojoOfJsonArray;
    }

    @Override
    public int getType() {
        return TYPE_GENERAL;
    }


}

DateItem .java

public class DateItem extends ListItem {

    private String date;

    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }

    @Override
    public int getType() {
        return TYPE_DATE;
    }
}

适配器
.java，如果您对如何制作简单的分段recyclerview不太了解，那么此适配器适用于recyclerview，那么我建议您仔细阅读这些内容并精通该领域，因为无论如何这还是比较棘手的：

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


    private Context mContext;
    List<ListItem> consolidatedList = new ArrayList<>();

    public Adapter(Context context, List<ListItem> consolidatedList) {
        this.consolidatedList = consolidatedList;
        this.mContext = context;


    }


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

        RecyclerView.ViewHolder viewHolder = null;
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());

        switch (viewType) {

            case ListItem.TYPE_GENERAL:
                View v1 = inflater.inflate(R.layout.items, parent,
                        false);
                viewHolder = new GeneralViewHolder(v1);
                break;

            case ListItem.TYPE_DATE:
                View v2 = inflater.inflate(R.layout.itemsh, parent, false);
                viewHolder = new DateViewHolder(v2);
                break;
        }

        return viewHolder;
    }

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

        switch (viewHolder.getItemViewType()) {

            case ListItem.TYPE_GENERAL:

                GeneralItem generalItem   = (GeneralItem) consolidatedList.get(position);
                GeneralViewHolder generalViewHolder= (GeneralViewHolder) viewHolder;
                generalViewHolder.txtTitle.setText(generalItem.getPojoOfJsonArray().getName());

                break;

            case ListItem.TYPE_DATE:
                DateItem dateItem = (DateItem) consolidatedList.get(position);
                DateViewHolder dateViewHolder = (DateViewHolder) viewHolder;

                dateViewHolder.txtTitle.setText(dateItem.getDate());
                // Populate date item data here

                break;
        }
    }





    // ViewHolder for date row item
    class DateViewHolder extends RecyclerView.ViewHolder {
        protected TextView txtTitle;

        public DateViewHolder(View v) {
            super(v);
            this.txtTitle = (TextView) v.findViewById(R.id.txt);

        }
    }

    // View holder for general row item
    class GeneralViewHolder extends RecyclerView.ViewHolder {
        protected TextView txtTitle;

        public GeneralViewHolder(View v) {
            super(v);
            this.txtTitle = (TextView) v.findViewById(R.id.txt);

        }
    }

    @Override
    public int getItemViewType(int position) {
        return consolidatedList.get(position).getType();
    }

    @Override
    public int getItemCount() {
        return consolidatedList != null ? consolidatedList.size() : 0;
    }

}

这有两个布局正在使用。因此所有