RecyclerView加载更多内容时出现ProgressBar错误 [英] RecyclerView load more with ProgressBar error

问题描述

我正在尝试在底部创建 Recyclerview onLoadMore，并使用 ProgressBar 。我已经尝试过此解决方案，但是在我的活动中使用onLoadMore方法永远不会被调用。请帮帮我。

I'm trying to create Recyclerview onLoadMore with ProgressBar at the bottom. I've tried this solution, but method onLoadMore in my Activity is never called. Please, help me.

这是我的适配器：

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

    private ArrayList<NewsDataModel> dataSet;
    private Context context;

    private final int VIEW_ITEM = 1;
    private final int VIEW_PROG = 0;

    // The minimum amount of items to have below your current scroll position before loading more.
    private int visibleThreshold = 2;
    private int lastVisibleItem, totalItemCount;
    private boolean loading;
    private OnLoadMoreListener onLoadMoreListener;

    public NewsAdapterTest(ArrayList<NewsDataModel> data, Context context, RecyclerView recyclerView) {
        this.dataSet = data;
        this.context = context;


        if (recyclerView.getLayoutManager() instanceof LinearLayoutManager) {

            final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
            recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
                @Override
                public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                    super.onScrolled(recyclerView, dx, dy);

                    totalItemCount = linearLayoutManager.getItemCount();
                    lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
                    if (!loading && totalItemCount <= (lastVisibleItem + visibleThreshold)) {
                        // End has been reached
                        // Do something
                        Log.i("newsAdaptertest", "onScrolled: End reached");
                        if (onLoadMoreListener != null) {
                            onLoadMoreListener.onLoadMore();
                        }
                        loading = true;
                    }
                }
            });
        }

    }

    public class MyViewHolder extends RecyclerView.ViewHolder {
        ExpandableTextView postMessage;
        TextView postTitle;
        TextView postSubTitle;
        ImageView authorImage;

        public MyViewHolder(View itemView) {
            super(itemView);
            this.authorImage = (ImageView) itemView.findViewById(R.id.header_image);
            this.postTitle = (TextView) itemView.findViewById(R.id.header_title);
            this.postSubTitle = (TextView) itemView.findViewById(R.id.header_subtitle);
            this.postMessage = (ExpandableTextView) itemView.findViewById(R.id.post_text_expand);
        }
    }

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

    @Override
    public int getItemViewType(int position) {
        return dataSet.get(position) != null ? VIEW_ITEM : VIEW_PROG;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        RecyclerView.ViewHolder vh;
        if (viewType == VIEW_ITEM) {
            View v = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.recycler_news, parent, false);

            vh = new MyViewHolder(v);
        } else {
            View v = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.recycler_progress, parent, false);

            vh = new ProgressViewHolder(v);
        }
        return vh;
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int listPosition) {
        if (holder instanceof MyViewHolder) {
            Binding Views...
        } else {
            ((ProgressViewHolder) holder).progressBar.setIndeterminate(true);
        }
    }

    public void setLoaded() {
        loading = false;
    }

    public void setOnLoadMoreListener(OnLoadMoreListener onLoadMoreListener) {
        this.onLoadMoreListener = onLoadMoreListener;
    }

    public interface OnLoadMoreListener {
        void onLoadMore();
    }

    public static class ProgressViewHolder extends RecyclerView.ViewHolder {
        public ProgressBar progressBar;

        public ProgressViewHolder(View v) {
            super(v);
            progressBar = (ProgressBar) v.findViewById(R.id.progressBar);
        }
    }

}

活动：

private static NewsAdapterTest adapter;
    private LinearLayoutManager layoutManager;
    private static RecyclerView recyclerView;
    private ArrayList<NewsDataModel> data = new ArrayList<NewsDataModel>();

recyclerView = (RecyclerView) findViewById(R.id.recyclerview_news);
        layoutManager = new LinearLayoutManager(this);
        adapter = new NewsAdapterTest(data, NewsActivity.this, recyclerView);

        recyclerView.setHasFixedSize(false);
        recyclerView.setLayoutManager(layoutManager);
        recyclerView.setItemAnimator(new DefaultItemAnimator());

        adapter.setOnLoadMoreListener(new NewsAdapterTest.OnLoadMoreListener() {
            @Override
            public void onLoadMore() {
                Log.i(TAG, "onLoadMore called");
                //add progress item
                data.add(null);
                adapter.notifyItemInserted(data.size() - 1);

                Log.i(TAG, "Loading new data... (" + Integer.toString(loadNumber) + ") posts");
                loadPosts(startLoadPosition, loadNumber);
                startLoadPosition += loadNumber;

                //remove progress item
                data.remove(data.size() - 1);
                adapter.notifyItemRemoved(data.size());
                //add items one by one

                adapter.setLoaded();
                //or you can add all at once but do not forget to call mAdapter.notifyDataSetChanged();
            }
        });

推荐答案

示例代码：

MainActivity：

MainActivity:

package com.example.sabari.recyclerviewsample;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private static RecyclerViewAdapter adapter;
    private LinearLayoutManager layoutManager;
    private static RecyclerView recyclerView;
    private List<Book> data = new ArrayList<>();

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

        getNextItems();
        recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
        layoutManager = new LinearLayoutManager(this);
        recyclerView.setHasFixedSize(false);
        recyclerView.setLayoutManager(layoutManager);
        adapter = new RecyclerViewAdapter(data, this, recyclerView);
        recyclerView.setAdapter(adapter);
        recyclerView.setItemAnimator(new DefaultItemAnimator());

        adapter.setOnLoadMoreListener(new RecyclerViewAdapter.OnLoadMoreListener() {
            @Override
            public void onLoadMore() {
                Log.i("LoadMore", "onLoadMore called");
                //add progress item
                data.add(null);
                adapter.notifyDataSetChanged();

                Log.i("LoadMore", "Loading new data... (" + 5 + ") posts");
                //remove progress item
                data.remove(data.size() - 1);

                getNextItems();

                adapter.notifyDataSetChanged();
                //add items one by one

                adapter.setLoaded();
            }
        });

    }

    private void getNextItems() {
        int itemCount = data.size();
        for (int i = itemCount; i <= itemCount + 5; i++) {
            Book book = new Book();
            book.title = "Title " + i;
            book.author = "Author " + i;
            book.description = "Description " + i;
            book.imageId = R.drawable.empty_user;
            data.add(book);
        }
    }

}

RecyclerViewAdapter：

RecyclerViewAdapter:

package com.example.sabari.recyclerviewsample;

import android.content.Context;
import android.support.v4.content.ContextCompat;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.TextView;

import java.util.List;

/**
 * Created by sabari on 2/8/2016.
 */
public class RecyclerViewAdapter extends RecyclerView.Adapter {
    private List<Book> dataSet;
    private Context context;

    private final int VIEW_ITEM = 1;
    private final int VIEW_PROG = 0;

    // The minimum amount of items to have below your current scroll position before loading more.
    private int visibleThreshold = 1;
    private int lastVisibleItem, totalItemCount;
    private boolean loading;
    private OnLoadMoreListener onLoadMoreListener;

    public RecyclerViewAdapter(List<Book> data, Context context, RecyclerView recyclerView) {
        this.dataSet = data;
        this.context = context;

        final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
        recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);
                final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
                totalItemCount = linearLayoutManager.getItemCount();
                lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
                if (!loading && totalItemCount <= (lastVisibleItem + visibleThreshold)) {
                    loading = true;
                    // End has been reached
                    // Do something
                    Log.i("AdapterScrolled", "onScrolled: End reached");
                    if (onLoadMoreListener != null) {
                        onLoadMoreListener.onLoadMore();
                    }

                }
            }
        });

    }

    public class MyViewHolder extends RecyclerView.ViewHolder {
        TextView description;
        TextView title;
        TextView author;
        ImageView profilePic;

        public MyViewHolder(View itemView) {
            super(itemView);
            this.profilePic = (ImageView) itemView.findViewById(R.id.user_profile_pic);
            this.title = (TextView) itemView.findViewById(R.id.title);
            this.author = (TextView) itemView.findViewById(R.id.author);
            this.description = (TextView) itemView.findViewById(R.id.description);
        }
    }

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

    @Override
    public int getItemViewType(int position) {
        return dataSet.get(position) != null ? VIEW_ITEM : VIEW_PROG;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        RecyclerView.ViewHolder vh;
        if (viewType == VIEW_ITEM) {
            View v = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.book_layout, parent, false);

            vh = new MyViewHolder(v);
        } else {
            View v = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.progress_bar_layout, parent, false);

            vh = new ProgressViewHolder(v);
        }
        return vh;
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        if (holder instanceof MyViewHolder) {
//                Binding Views...
            Book book = dataSet.get(position);
            ((MyViewHolder) holder).profilePic.setImageDrawable(ContextCompat.getDrawable(context, book.imageId));
            ((MyViewHolder) holder).title.setText(book.title);
            ((MyViewHolder) holder).author.setText(book.author);
            ((MyViewHolder) holder).description.setText(book.description);
        } else {
            ((ProgressViewHolder) holder).progressBar.setIndeterminate(true);
        }
    }

    public void setLoaded() {
        loading = false;
    }

    public void setOnLoadMoreListener(OnLoadMoreListener onLoadMoreListener) {
        this.onLoadMoreListener = onLoadMoreListener;
    }

    public interface OnLoadMoreListener {
        void onLoadMore();
    }

    public static class ProgressViewHolder extends RecyclerView.ViewHolder {
        public ProgressBar progressBar;

        public ProgressViewHolder(View v) {
            super(v);
            progressBar = (ProgressBar) v.findViewById(R.id.progressBar);
        }
    }
}

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