Please I need your help, I need to display my list in mode list or grid, that's why I use recyclerview but that does not work and give me the following error related to "recyclerView.setLayoutManager(new LinearLayoutManager(this));
However when I used listview before that worked fine!
can you help me please, thanks
this my activity_videos
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
android:id="@+id/parentLayout"
tools:context=".UI.Videos">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/AppTheme.AppBarOverlay"
>
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="#FFFFFF"
app:popupTheme="@style/AppTheme.PopupOverlay" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Videos"
android:textColor="#303F9F"
android:layout_gravity="center"
android:id="@+id/Videos" />
</android.support.v7.widget.Toolbar>
</android.support.design.widget.AppBarLayout>
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<include
layout="@layout/content_videos"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<android.support.design.widget.NavigationView
android:id="@+id/nav_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="@layout/nav_header_main"
app:menu="@menu/activity_main_drawer"/>
</android.support.v4.widget.DrawerLayout>
</android.support.design.widget.CoordinatorLayout>
my content video :
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context=".UI.Videos"
tools:showIn="@layout/activity_videos">
<Space
android:layout_width="20px"
android:layout_height="20px"
android:id="@+id/space" />
<android.support.v4.widget.SwipeRefreshLayout
android:id="@+id/activity_main_swipe_refresh_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/space"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="56dp">
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:scrollbars="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</android.support.v4.widget.SwipeRefreshLayout>
</RelativeLayout>
my cutom list adabtor :
public class CustomListViewAdapterV extends RecyclerView.Adapter<CustomListViewAdapterV.ViewHolder> {
List<Video> videoList;
Context context;
// Constructors
public CustomListViewAdapterV(Context context, ArrayList<Video> objects) {
this.context = context;
videoList = objects;
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_videos, parent, false);
return new ViewHolder(v);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
Video item = videoList.get(position);
holder.textViewTitle.setText(item.getTitle());
// holder.textViewCreated_time.setText(item.getCreated_time());
// holder.textViewId.setText(item.getId());
Picasso.with(context).load(item.getThumbnail_medium_url()).placeholder(R.mipmap.ic_launcher).error(R.mipmap.ic_launcher).into(holder.imageView);
holder.rootView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
}
});
}
@Override
public int getItemCount() {
return videoList.size();
}
public static class ViewHolder extends RecyclerView.ViewHolder {
RelativeLayout rootView;
ImageView imageView;
TextView textViewTitle;
// public final TextView textViewCreated_time;
// public final TextView textViewId;
private ViewHolder(View rootView) {
super(rootView);
this.imageView = imageView;
this.textViewTitle = textViewTitle;
// this.textViewCreated_time = textViewCreated_time;
// this.textViewId = textViewId;
}
public static void create(RelativeLayout rootView) {
ImageView imageView = (ImageView) rootView.findViewById(R.id.imageView);
TextView textViewTitle = (TextView) rootView.findViewById(R.id.textViewTitle);
// TextView textViewCreated_time = (TextView) rootView.findViewById(R.id.textViewCreated_time);
// TextView textViewId = (TextView) rootView.findViewById(R.id.textViewId);
}
}
}
and this is my mainactivity:
public class Videos extends MainActivity {
private View parentView;
private ArrayList<Video> videoList;
private CustomListViewAdapterV adapter;
SwipeRefreshLayout mSwipeRefreshLayout;
RecyclerView recyclerView;
@Override
protected void onCreate(Bundle savedInstanceState) {
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
adapter = new CustomListViewAdapterV(Videos.this, videoList);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_videos);
mSwipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.activity_main_swipe_refresh_layout);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
videoList = new ArrayList<>();
parentView = findViewById(R.id.parentLayout);
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
mSwipeRefreshLayout.setColorSchemeResources(R.color.blue, R.color.green, R.color.blue);
mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
doYourUpdate();
}
}
);
ItemClickSupport.addTo(recyclerView).setOnItemClickListener(new ItemClickSupport.OnItemClickListener() {
@Override
public void onItemClicked(RecyclerView recyclerView, int position, View v) {
Intent intent = new Intent(getApplicationContext(), Daylimotion.class);
startActivity(intent);
}
});
if (InternetConnection.isNetworkAvailable(getApplicationContext())) {
//Creating an object of our api interface
ApiInterface api = ApiClientV.getApiInterface();
/**
* Calling JSON
*/
Call<VideoList> call = api.getJsn();
/**
* Enqueue Callback will be call when get response...
*/
call.enqueue(new Callback<VideoList>() {
@Override
public void onResponse(Call<VideoList> call, Response<VideoList> response) {
//Dismiss Dialog
if(response.isSuccessful()) {
/**
* Got Successfully
*/
videoList = response.body().getList();
// adapter.notifiyDataSetChanged();
/**
* Binding that List to Adapter
*/
//This is to show data for first time when we run the app.
adapter = new CustomListViewAdapterV(Videos.this, videoList);
recyclerView.setAdapter(adapter);
} else {
Snackbar.make(parentView, R.string.string_some_thing_wrong, Snackbar.LENGTH_LONG).show();
}
}
@Override
public void onFailure(Call<VideoList> call, Throwable t) {
}
});
} else {
Snackbar.make(parentView, R.string.string_internet_connection_not_available, Snackbar.LENGTH_LONG).show();
}
}
private void doYourUpdate() {
mSwipeRefreshLayout.setRefreshing(false); // Disables the refresh icon
}
@Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.show, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int layoutId = R.layout.list_item;
int spanCount = 2;
switch (item.getItemId()) {
case R.id.linearVertical: // Vertical scrollable using LinearLayoutManager.
recyclerView.setLayoutManager(new LinearLayoutManager(this));
break;
case R.id.staggeredGridviewVertical: // Vertical scrollable using StaggeredGridLayoutManager.
recyclerView.setLayoutManager(new StaggeredGridLayoutManager(spanCount, StaggeredGridLayoutManager.VERTICAL));
break;
}
return super.onOptionsItemSelected(item);
}
the error that have is :
FATAL EXCEPTION: main
Process: com.example.sajdour.fcg_sajdour, PID: 23620
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.sajdour.fcg_sajdour/com.example.sajdour.fcg_sajdour.UI.Videos}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3254)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3350)
at android.app.ActivityThread.access$1100(ActivityThread.java:222)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1795)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7229)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)' on a null object reference
at com.example.sajdour.fcg_sajdour.UI.Videos.onCreate(Videos.java:46)
at android.app.Activity.performCreate(Activity.java:6876)
答案 0 :(得分：1)
You should create grid layout manager:
recyclerView.setLayoutManager(new GridLayoutManager(this, 2));
About error. Your recycler view is null in onCreate(). You should invoke findViewById(R.id.myRecycler) after setContentView() and before recyclerView methods invocation. In your case:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_videos);
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
adapter = new CustomListViewAdapterV(Videos.this, videoList);
...
}
答案 1 :(得分：1)
your recyclerView is null. initialize recyclerview after calling super.onCreate() & setContentView(). Change the first 5 lines in your oncreate method of your Videos Activity
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_videos);
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
adapter = new CustomListViewAdapterV(Videos.this, videoList);
答案 2 :(得分：0)
Your actual problem is that you are trying to do stuff before these two. These two should come before anything to avoid the error you got
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_videos);
So, something like:
//A bunch of code
@Override
protected void onCreate(Bundle savedInstanceState) {
//PAY ATTENTION HERE
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_videos);
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
adapter = new CustomListViewAdapterV(Videos.this, videoList);
mSwipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.activity_main_swipe_refresh_layout);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
//even more code