Android RecyclerView无限滚动问题
我试图用RecyclerView实现无休止的无限滚动,但我只获得前10条记录,没有获得下10条记录,甚至在尝试滚动底部时没有任何进展Android RecyclerView无限滚动问题,android,json,android-recyclerview,infinite-scroll,endlessscroll,Android,Json,Android Recyclerview,Infinite Scroll,Endlessscroll,我试图用RecyclerView实现无休止的无限滚动,但我只获得前10条记录,没有获得下10条记录,甚至在尝试滚动底部时没有任何进展 而我本来打算在scroll上获得接下来的10张唱片等等。。。但只获得前10项记录 这里我上传了我的JSON,但我无法从同一个url获取数据,这就是为什么我使用客户端的url和本地主机 我正在学习教程 这是我的完整代码,我可以知道我在哪里出错吗 JSON: { "names": [ { "name": "Name 1" },
而我本来打算在scroll上获得接下来的10张唱片等等。。。但只获得前10项记录 这里我上传了我的JSON,但我无法从同一个url获取数据,这就是为什么我使用客户端的url和本地主机 我正在学习教程 这是我的完整代码,我可以知道我在哪里出错吗 JSON:
{
"names": [
{
"name": "Name 1"
},
{
"name": "Name 2"
},
....
{
"name": "Name 60"
}
]
}
D/name -(13759): Name 1
D/name -(13759): Name 2
.......................
D/name -(13759): Name 60
public class DataAdapter extends RecyclerView.Adapter {
private final int VIEW_ITEM = 1;
private final int VIEW_PROG = 0;
private List<Student> studentList;
// The minimum amount of items to have below your current scroll position
// before loading more.
private int visibleThreshold = 5;
private int lastVisibleItem, totalItemCount;
private boolean loading;
private OnLoadMoreListener onLoadMoreListener;
public DataAdapter(List<Student> students, RecyclerView recyclerView) {
studentList = students;
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
if (onLoadMoreListener != null) {
onLoadMoreListener.onLoadMore();
}
loading = true;
}
}
});
}
}
@Override
public int getItemViewType(int position) {
return studentList.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.list_row, parent, false);
vh = new StudentViewHolder(v);
} else {
View v = LayoutInflater.from(parent.getContext()).inflate(
R.layout.progress_item, parent, false);
vh = new ProgressViewHolder(v);
}
return vh;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceof StudentViewHolder) {
Student singleStudent= (Student) studentList.get(position);
((StudentViewHolder) holder).tvName.setText(singleStudent.getName());
((StudentViewHolder) holder).student= singleStudent;
} else {
((ProgressViewHolder) holder).progressBar.setIndeterminate(true);
}
}
public void setLoaded() {
loading = false;
}
@Override
public int getItemCount() {
return studentList.size();
}
public void setOnLoadMoreListener(OnLoadMoreListener onLoadMoreListener) {
this.onLoadMoreListener = onLoadMoreListener;
}
//
public static class StudentViewHolder extends RecyclerView.ViewHolder {
public TextView tvName;
public Student student;
public StudentViewHolder(View v) {
super(v);
tvName = (TextView) v.findViewById(R.id.tvName);
v.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(v.getContext(),
"OnClick :" + student.getName(),
Toast.LENGTH_SHORT).show();
}
});
}
}
public static class ProgressViewHolder extends RecyclerView.ViewHolder {
public ProgressBar progressBar;
public ProgressViewHolder(View v) {
super(v);
progressBar = (ProgressBar) v.findViewById(R.id.progressBar1);
}
}
}
public interface OnLoadMoreListener {
void onLoadMore();
}
日志:
{
"names": [
{
"name": "Name 1"
},
{
"name": "Name 2"
},
....
{
"name": "Name 60"
}
]
}
D/name -(13759): Name 1
D/name -(13759): Name 2
.......................
D/name -(13759): Name 60
public class DataAdapter extends RecyclerView.Adapter {
private final int VIEW_ITEM = 1;
private final int VIEW_PROG = 0;
private List<Student> studentList;
// The minimum amount of items to have below your current scroll position
// before loading more.
private int visibleThreshold = 5;
private int lastVisibleItem, totalItemCount;
private boolean loading;
private OnLoadMoreListener onLoadMoreListener;
public DataAdapter(List<Student> students, RecyclerView recyclerView) {
studentList = students;
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
if (onLoadMoreListener != null) {
onLoadMoreListener.onLoadMore();
}
loading = true;
}
}
});
}
}
@Override
public int getItemViewType(int position) {
return studentList.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.list_row, parent, false);
vh = new StudentViewHolder(v);
} else {
View v = LayoutInflater.from(parent.getContext()).inflate(
R.layout.progress_item, parent, false);
vh = new ProgressViewHolder(v);
}
return vh;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceof StudentViewHolder) {
Student singleStudent= (Student) studentList.get(position);
((StudentViewHolder) holder).tvName.setText(singleStudent.getName());
((StudentViewHolder) holder).student= singleStudent;
} else {
((ProgressViewHolder) holder).progressBar.setIndeterminate(true);
}
}
public void setLoaded() {
loading = false;
}
@Override
public int getItemCount() {
return studentList.size();
}
public void setOnLoadMoreListener(OnLoadMoreListener onLoadMoreListener) {
this.onLoadMoreListener = onLoadMoreListener;
}
//
public static class StudentViewHolder extends RecyclerView.ViewHolder {
public TextView tvName;
public Student student;
public StudentViewHolder(View v) {
super(v);
tvName = (TextView) v.findViewById(R.id.tvName);
v.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(v.getContext(),
"OnClick :" + student.getName(),
Toast.LENGTH_SHORT).show();
}
});
}
}
public static class ProgressViewHolder extends RecyclerView.ViewHolder {
public ProgressBar progressBar;
public ProgressViewHolder(View v) {
super(v);
progressBar = (ProgressBar) v.findViewById(R.id.progressBar1);
}
}
}
public interface OnLoadMoreListener {
void onLoadMore();
}
这是我的更新代码,我正在使用它解析JSON数据
MainActivity.java:已更新
public class MainActivity extends AppCompatActivity {
private Toolbar toolbar;
private TextView tvEmptyView;
private RecyclerView mRecyclerView;
private DataAdapter mAdapter;
private LinearLayoutManager mLayoutManager;
private ArrayList<Student> studentList;
protected Handler handler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar = (Toolbar) findViewById(R.id.toolbar);
tvEmptyView = (TextView) findViewById(R.id.empty_view);
mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
studentList = new ArrayList<Student>();
handler = new Handler();
if (toolbar != null) {
setSupportActionBar(toolbar);
getSupportActionBar().setTitle("Android Students");
}
loadData();
}
// load initial data
private void loadData() {
new Parser().execute("http://10.0.2.2/jsons/mytest.txt");
}
class Parser extends AsyncTask<String, Void, Boolean> {
ProgressDialog dialog;
@Override
protected void onPreExecute() {
super.onPreExecute();
dialog = new ProgressDialog(MainActivity.this);
dialog.show();
dialog.setCancelable(false);
}
@Override
protected Boolean doInBackground(String... urls) {
try {
//------------------>>
HttpGet httppost = new HttpGet(urls[0]);
HttpClient httpclient = new DefaultHttpClient();
HttpResponse response = httpclient.execute(httppost);
// StatusLine stat = response.getStatusLine();
int status = response.getStatusLine().getStatusCode();
if (status == 200) {
HttpEntity entity = response.getEntity();
String data = EntityUtils.toString(entity);
JSONObject jsono = new JSONObject(data);
JSONArray jarray = jsono.getJSONArray("names");
for (int i = 0; i < jarray.length(); i++) {
JSONObject object = jarray.getJSONObject(i);
Student actor = new Student();
actor.setName(object.getString("name"));
Log.d("name - ", object.getString("name"));
studentList.add(actor);
}
Log.d("MainActivity:StudentList ", "The size "+studentList.size());
return true;
}
//------------------>>
} catch (ParseException e1) {
e1.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return false;
}
protected void onPostExecute(Boolean result) {
dialog.cancel();
Log.d("MainActivity:StudentList ", "The size "+studentList.size());
ArrayList< Student > temArray =
new ArrayList< Student >(studentList.subList(0, 10));
mAdapter = new DataAdapter(temArray, mRecyclerView);
Log.d("MainActivity:TempList ", "The size "+temArray.size());
// set the adapter object to the Recyclerview
mRecyclerView.setAdapter(mAdapter);
// use this setting to improve performance if you know that changes
// in content do not change the layout size of the RecyclerView
mRecyclerView.setHasFixedSize(true);
mLayoutManager = new LinearLayoutManager(MainActivity.this);
// use a linear layout manager
mRecyclerView.setLayoutManager(mLayoutManager);
if (studentList.isEmpty()) {
mRecyclerView.setVisibility(View.GONE);
tvEmptyView.setVisibility(View.VISIBLE);
} else {
mRecyclerView.setVisibility(View.VISIBLE);
tvEmptyView.setVisibility(View.GONE);
}
mAdapter.setOnLoadMoreListener(new OnLoadMoreListener() {
@Override
public void onLoadMore() {
//add null , so the adapter will check view_type and show progress bar at bottom
studentList.add(null);
mAdapter.notifyItemInserted(studentList.size() - 1);
handler.postDelayed(new Runnable() {
@Override
public void run() {
// remove progress item
studentList.remove(studentList.size() - 1);
mAdapter.notifyItemRemoved(studentList.size());
//add items one by one
int start = studentList.size();
int end = start + 10;
for (int i = start + 1; i < end; i++) {
mAdapter.notifyItemInserted(studentList.size());
}
mAdapter.setLoaded();
//or you can add all at once but do not forget to call mAdapter.notifyDataSetChanged();
}
}, 2000);
}
});
}
}
}
1.
将前11个recyclerview项设置为空白(并显示进度条
连续),请参见下面的屏幕截图:
将加载数据的方法更改为:
private void loadData() {
new Parser().execute("http://clienturl.com/jsons/mytest.txt");
}
2.
而我应该得到前10条记录,然后滚动下10条
唱片等等
将onPostExecute
解析器的方法更改为:
protected void onPostExecute(Boolean result) {
dialog.cancel();
ArrayList< Student > temArray =
new ArrayList< Student >(studentList.subList(0, 10));
mAdapter = new DataAdapter(temArray, mRecyclerView);
// set the adapter object to the Recyclerview
mRecyclerView.setAdapter(mAdapter);
}
试着换个颜色
int i = start + 1; i <= end; i++
inti=start+1;ifor(int i=start+1;i
尝试更改NotifyItemRange
yourCurrentList.addAll(newData);
mAdapter.notifyItemRangeChanged(yourCurretList.size() + 1, newDataSize);
我想这会对您有所帮助。问题1:在为RecyclerView设置LayoutManager
之前,您已经创建了一个mAdapter
的新实例。因此,要添加的ScrollListener
的DataAdapter中的构造函数代码不会执行,因为recyclerView.getLayoutManager()
返回null
:
if (recyclerView.getLayoutManager() instanceof LinearLayoutManager){
// code to add ScrollListener is never executed
}
修复:首先为Recyclerview设置布局管理器
,然后创建适配器,如下所示:
// use a linear layout manager
mRecyclerView.setLayoutManager(mLayoutManager);
mAdapter = new DataAdapter(temArray, mRecyclerView);
// set the adapter object to the Recyclerview
mRecyclerView.setAdapter(mAdapter);
Issue-2:您已经使用temArray
创建了DataAdapter
,但是在onLoadMore()
中,您正在使用studentList
添加/删除新项目,因为studentList
没有与mAdapter
绑定,您的更改不会反映在UI中
修复:将temArray
声明为类级变量,并使用temArray
操作项
//class variable
private ArrayList<Student> temArray = new ArrayList<Student>();
handler.postDelayed(new Runnable() {
@Override public void run() {
// remove progress item
temArray.remove(temArray.size() - 1);
mAdapter.notifyItemRemoved(temArray.size());
//add items one by one
int start = temArray.size();
int end = start + 10;
if(end<=studentList.size()){
temArray.addAll(studentList.subList(start,end));
}
mAdapter.setLoaded();
}
}, 2000);
//类变量
private ArrayList temArray=new ArrayList();
handler.postDelayed(新的Runnable(){
@重写公共无效运行(){
//删除进度项目
temArray.remove(temArray.size()-1);
notifyItemRemoved(temArray.size());
//逐个添加项目
int start=temArray.size();
int end=开始+10;
如果(结束更换
private List<Student> studentList;
与
对于检测列表末尾,您可以使用
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
// When went to the end of the list, load more posts
if (newState == RecyclerView.SCROLL_STATE_IDLE) {
if (linearLayoutManager.findLastVisibleItemPosition() >= linearLayoutManager.getItemCount() - 1) {
// Grow List
}
}
}
也用于添加加载项。在适配器中添加此代码
public void addLoadingView(){
list.add(new Object());
notifyDataSetChanged();
}
我曾经有过同样的问题,我用这个代码解决了它。。。
首先,创建这个类
public abstract class EndlessOnScrollListener extends OnScrollListener {
public static String TAG = EndlessOnScrollListener.class.getSimpleName();
// use your LayoutManager instead
private LinearLayoutManager llm;
public EndlessOnScrollListener(LinearLayoutManager sglm) {
this.lm = llm;
}
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
if (!recyclerView.canScrollVertically(1)) {
onScrolledToEnd();
}
}
public abstract void onScrolledToEnd();
}
第二,在你的活动中使用这个
recyclerView.addOnScrollListener(new EndlessOnScrollListener() {
@Override
public void onScrolledToEnd() {
if (!loading) {
loading = true;
// add 10 by 10 to tempList then notify changing in data
}
loading = false;
}
});
这对我很有用……我希望它对你有用。mAdapter.setOnLoadMoreListener(新的OnLoadMoreListener(){
mAdapter.setOnLoadMoreListener(new OnLoadMoreListener() {
@Override
public void onLoadMore() {
//add null , so the adapter will check view_type and show progress bar at bottom
studentList.add(null);
mAdapter.notifyItemInserted(studentList.size() - 1);
handler.postDelayed(new Runnable() {
@Override
public void run() {
// remove progress item
studentList.remove(studentList.size() - 1);
mAdapter.notifyItemRemoved(studentList.size());
//add items one by one
int start = studentList.size();
int end = start + 10;
for (int i = start + 1; i < end; i++) {
// studentList.add();
mAdapter.notifyItemInserted(studentList.size());
}
mAdapter.setLoaded();
//or you can add all at once but do not forget to call mAdapter.notifyDataSetChanged();
}
}, 2000);
}
});
@凌驾
public void onLoadMore(){
//添加null,这样适配器将检查视图类型并在底部显示进度条
studentList.add(空);
mAdapter.notifyItemInserted(studentList.size()-1);
handler.postDelayed(新的Runnable(){
@凌驾
公开募捐{
//删除进度项目
studentList.remove(studentList.size()-1);
mAdapter.notifyItemRemoved(studentList.size());
//逐个添加项目
int start=studentList.size();
int end=开始+10;
对于(int i=start+1;i
好的,你插入了进度条,然后你也删除了它,但是你从来没有插入下一个要显示的学生。。。
类似studentList.add()的内容
我希望这解决了您的问题…祝您好运..您能在浏览器中执行,看看您得到了什么吗?您能在LogCat
中记录数据,看看它打印了什么吗?您没有在loadmore中的循环中添加项目,因为您一次加载所有项目,我想您不需要加载更多。您没有更改visibilitpost execute.addif(studentList.isEmpty()){mRecyclerView.setVisibility(view.GONE);tvEmptyView.setVisibility(view.VISIBLE);}else{mRecyclerView.setVisibility(view.VISIBLE);tvEmptyView.setVisibility(view.GONE);}
在异步任务的后期执行中,您是否在以下位置看到了代码?@Oreo:ok movemAdapter.setOnLoadMoreListener
onPostExecute aftermRecyclerView.setAdapter(mAdapter)中的方法代码;
line@Oreo:已修复或仍面临相同问题?@Oreo:在学生列表中获取数据
?使用日志并检查学生列表
和temArray
ArrayListSize@Oreo:请在onPostExecute
方法中添加调试器,并检查它是否正在执行?让我们来看看。我本来打算在scroll上获得接下来的10条记录,以此类推在……但请只拿到前10张唱片
recyclerView.addOnScrollListener(new EndlessOnScrollListener() {
@Override
public void onScrolledToEnd() {
if (!loading) {
loading = true;
// add 10 by 10 to tempList then notify changing in data
}
loading = false;
}
});
mAdapter.setOnLoadMoreListener(new OnLoadMoreListener() {
@Override
public void onLoadMore() {
//add null , so the adapter will check view_type and show progress bar at bottom
studentList.add(null);
mAdapter.notifyItemInserted(studentList.size() - 1);
handler.postDelayed(new Runnable() {
@Override
public void run() {
// remove progress item
studentList.remove(studentList.size() - 1);
mAdapter.notifyItemRemoved(studentList.size());
//add items one by one
int start = studentList.size();
int end = start + 10;
for (int i = start + 1; i < end; i++) {
// studentList.add();
mAdapter.notifyItemInserted(studentList.size());
}
mAdapter.setLoaded();
//or you can add all at once but do not forget to call mAdapter.notifyDataSetChanged();
}
}, 2000);
}
});