我正在尝试在底部创建Recyclerview onLoadMore，ProgressBar。我尝试了this solution，但我的Activity中的onLoadMore方法从未被调用过。求你帮帮我。
这是我的Adapter：
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);
}
}
}
我的活动：
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();
}
});
答案 0 :(得分：3)
示例代码：
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：
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);
}
}
}