Android 如何检查Recyclerviews是否为空
您好,我在CardView中有一个recyclerview,我通过截取请求从服务器(JSONObject)获取数据。如何检测我的recyclerview是否为空?我试图检查ArrayList是否为空,但似乎不起作用,如何解决?谢谢 这是我的片段:Android 如何检查Recyclerviews是否为空,android,json,android-recyclerview,fragment,Android,Json,Android Recyclerview,Fragment,您好,我在CardView中有一个recyclerview,我通过截取请求从服务器(JSONObject)获取数据。如何检测我的recyclerview是否为空?我试图检查ArrayList是否为空,但似乎不起作用,如何解决?谢谢 这是我的片段: public class Tab1History extends Fragment implements SwipeRefreshLayout.OnRefreshListener { SwipeRefreshLayout mSwipeRefreshL
public class Tab1History extends Fragment implements SwipeRefreshLayout.OnRefreshListener
{
SwipeRefreshLayout mSwipeRefreshLayout;
private RecyclerView recyclerView;
private CespiteAdapter adapter;
UserSessionManager session;
ConnectionDetector cd;
private static final String URL_DATA = "http://myfile.php";
private List<CespiteOgg> cespiteOggList;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
cd = new ConnectionDetector(getActivity());
View rootView = inflater.inflate(R.layout.tab1history, container, false);
recyclerView = (RecyclerView) rootView.findViewById(R.id.my_recycler_view);
recyclerView.setHasFixedSize(true);//every item of the RecyclerView has a fix size
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
cespiteOggList = new ArrayList<>();
// SwipeRefreshLayout
mSwipeRefreshLayout = (SwipeRefreshLayout) rootView.findViewById(R.id.swipe_container);
mSwipeRefreshLayout.setOnRefreshListener(this);
mSwipeRefreshLayout.setColorSchemeResources(
R.color.colorAccent
);
/**
* Showing Swipe Refresh animation on activity create
* As animation won't start on onCreate, post runnable is used
*/
mSwipeRefreshLayout.post(new Runnable() {
@Override
public void run() {
mSwipeRefreshLayout.setRefreshing(true);
// Fetching data from server
loadRecyclerViewData();
}
});
return rootView;
}
/**
* This method is called when swipe refresh is pulled down
*/
@Override
public void onRefresh()
{
if(cd.isNetworkAvailable())
{
// Fetching data from server
loadRecyclerViewData();
}
else
{
Toast.makeText(getActivity(), "Nessuna connessione ad internet!", Toast.LENGTH_SHORT).show();
mSwipeRefreshLayout.setRefreshing(false);
}
}
private void loadRecyclerViewData()
{
cespiteOggList.clear();
//cespiteOggList = new ArrayList<>();
// Showing refresh animation before making http call
mSwipeRefreshLayout.setRefreshing(true);
// Session class instance
session = new UserSessionManager(getActivity());
//get user data from session
HashMap<String, String> user = session.getUserDetails();
//get name
String name = user.get(UserSessionManager.KEY_NAME);
// get username
final String usernameUtente = user.get(UserSessionManager.KEY_USERNAME);
StringRequest stringRequest = new StringRequest(Request.Method.POST,
URL_DATA,
new Response.Listener<String>() {
@Override
public void onResponse(String s) {
try {
JSONObject jsonObject = new JSONObject(s);
JSONArray array = jsonObject.getJSONArray("dates");
for(int i=0; i<array.length(); i++)
{
JSONObject o = array.getJSONObject(i);
CespiteOgg item = new CespiteOgg(
o.getString("CodNumInventario"),
o.getString("Nome"),
o.getString("DtCatalogazione"),
o.getString("CodIdA"),
o.getString("username")
);
cespiteOggList.add(item);
}
adapter = new CespiteAdapter(cespiteOggList, getActivity());
recyclerView.setAdapter(adapter);
} catch (JSONException e) {
e.printStackTrace();
}
// Stopping swipe refresh
mSwipeRefreshLayout.setRefreshing(false);
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
// Stopping swipe refresh
mSwipeRefreshLayout.setRefreshing(false);
}
})
{
@Override
protected Map<String, String> getParams() throws AuthFailureError {
Map<String, String> params = new HashMap<String, String>();
params.put("Username", usernameUtente);
return params;
}
};
RegisterRequest.getmInstance(getActivity()).addToRequestque(stringRequest);
}
}
public类Tab1History扩展片段实现SwipeRefreshLayout.OnRefreshListener
{
SwipeRefreshLayout mSwipeRefreshLayout;
私人回收站;
专用CespiteAdapter适配器;
用户会话管理器会话;
连接检测器cd;
私有静态最终字符串URL_DATA=”http://myfile.php";
私人名单;种族主义者;
@凌驾
创建视图上的公共视图(布局、充气机、视图组容器、,
Bundle savedInstanceState)
{
cd=新的ConnectionDetector(getActivity());
视图根视图=充气机。充气(R.layout.tab1历史记录,容器,false);
recyclerView=(recyclerView)rootView.findViewById(R.id.my\u recycler\u视图);
setHasFixedSize(true);//recyclerView的每个项都有一个固定大小
setLayoutManager(新的LinearLayoutManager(getContext());
cespiteoglist=newarraylist();
//SwipeRefreshLayout
mSwipeRefreshLayout=(SwipeRefreshLayout)rootView.findViewById(R.id.swipe_容器);
mSwipeRefreshLayout.setOnRefreshListener(此);
mSwipeRefreshLayout.setColorSchemeResources(
颜色重音
);
/**
*在“创建活动”上显示滑动刷新动画
*由于动画不会在onCreate上启动,因此会使用post runnable
*/
mSwipeRefreshLayout.post(新的Runnable(){
@凌驾
公开募捐{
mSwipeRefreshLayout.setRefreshing(true);
//从服务器获取数据
loadRecycleServiceWdata();
}
});
返回rootView;
}
/**
*下拉滑动刷新时调用此方法
*/
@凌驾
公共void onRefresh()
{
if(cd.isNetworkAvailable())
{
//从服务器获取数据
loadRecycleServiceWdata();
}
其他的
{
Toast.makeText(getActivity(),“Nessuna connessione广告互联网!”,Toast.LENGTH_SHORT.show();
mSwipeRefreshLayout.setRefresh(false);
}
}
私有void loadRecyclerViewData()
{
Cespiteoggleist.clear();
//cespiteoglist=newarraylist();
//在进行http调用之前显示刷新动画
mSwipeRefreshLayout.setRefreshing(true);
//会话类实例
session=newusersessionmanager(getActivity());
//从会话获取用户数据
HashMap user=session.getUserDetails();
//得名
String name=user.get(UserSessionManager.KEY\u name);
//获取用户名
最后一个字符串usernameunte=user.get(UserSessionManager.KEY\u USERNAME);
StringRequest StringRequest=新StringRequest(Request.Method.POST,
URL\u数据,
新的Response.Listener(){
@凌驾
公共void onResponse(字符串s){
试一试{
JSONObject JSONObject=新的JSONObject;
JSONArray数组=jsonObject.getJSONArray(“日期”);
对于(int i=0;i您可以覆盖适配器getItemCount()以返回列表的大小,并从您的RecyclerView()获取适配器。将此部分添加到适配器:
@Override
public int getItemCount() {
return cespiteOggList.size();
}
您可以通过以下方式获得recyclerView的大小:
adapter.getItemCount()
您可能需要覆盖onCreateViewHolder
、onBindViewHolder
和getItemCount
。值getItemCount
返回的值等于RecyclerView的项目计数。您可以使用getItemCount
if (adapter.getItemCount() == 0)
{
Toast.makeText(getApplicationContext(), "NO Data Found",Toast.LENGTH_SHORT).show();
}
如果您正在从服务器获取数据,则不必检查回收器视图项的大小,您可以在(array.length>0){//表示您有数据,所以回收器视图不为空}的情况下检查通过截取来的数据的大小
if (adapter.getItemCount() == 0)
{
Toast.makeText(getApplicationContext(), "NO Data Found",Toast.LENGTH_SHORT).show();
}