问题描述
我知道如何在ListView中显示EmptyView，但它确实使我在RecyclerView中感到困惑，并且也从firebasedabase获取数据。 有人可以告诉我如何在下面的代码中显示空视图吗？
XML文件
<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:id="@+id/content_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="com.example.dexter.ddiary.MainActivity"
tools:showIn="@layout/app_bar_main">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<LinearLayout
android:id="@+id/main_date_display"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:padding="4dp">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/main_date"
android:gravity="center"
android:textSize="24sp" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.RecyclerView
android:id="@+id/notes_list"
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v7.widget.RecyclerView>
</LinearLayout>
</LinearLayout>
</RelativeLayout>
MainActivity.java
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener, View.OnClickListener {
private LinearLayoutManager mlinearLayoutManager;
private RecyclerView mNotesList;
private FirebaseAuth auth;
private FirebaseAuth.AuthStateListener mAuthListener;
private DatabaseReference mDatabase;
private DatabaseReference mDatabaseUsers;
private DatabaseReference mDatabaseLike;
private DatabaseReference mDataCurrentUser;
private boolean mProcessLike = false;
private TextView userName;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
auth = FirebaseAuth.getInstance();
mAuthListener = new FirebaseAuth.AuthStateListener() {
@Override
public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
if (firebaseAuth.getCurrentUser() == null) {
Intent loginIntent = new Intent(MainActivity.this, AccountActivity.class);
loginIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(loginIntent);
}
}
};
String currentDateString = DateFormat.getDateInstance(DateFormat.FULL).format(new Date());
TextView textView = (TextView) findViewById(R.id.main_date);
textView.setText(currentDateString);
mDatabaseLike = FirebaseDatabase.getInstance().getReference().child("Likes");
mDatabase = FirebaseDatabase.getInstance().getReference().child("Notes");
mDatabaseUsers = FirebaseDatabase.getInstance().getReference().child("Users");
mDatabase.keepSynced(true);
mDatabaseUsers.keepSynced(true);
mDatabaseLike.keepSynced(true);
mNotesList = (RecyclerView) findViewById(R.id.notes_list);
mNotesList.setHasFixedSize(true);
mlinearLayoutManager = new LinearLayoutManager(this);
mlinearLayoutManager.setStackFromEnd(true);
mlinearLayoutManager.setReverseLayout(true);
mNotesList.setLayoutManager(mlinearLayoutManager);
checkUserExist();
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(this);
FloatingActionButton fab_chat = (FloatingActionButton) findViewById(R.id.fab_chat);
fab_chat.setOnClickListener(this);
FloatingActionButton fab_post = (FloatingActionButton) findViewById(R.id.fab_post);
fab_post.setOnClickListener(this);
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);
userName = (TextView)navigationView.getHeaderView(0).findViewById(R.id.user_name);
}
@Override
protected void onStart() {
super.onStart();
auth.addAuthStateListener(mAuthListener);
FirebaseRecyclerAdapter<Notes, NotesViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Notes, NotesViewHolder>(
Notes.class,
R.layout.notes_row,
NotesViewHolder.class,
mDatabase
) {
@Override
protected void populateViewHolder(NotesViewHolder viewHolder, Notes model, int position) {
final String post_key = getRef(position).getKey();
viewHolder.setDate(model.getDate());
viewHolder.setTime(model.getTime());
viewHolder.setTitle(model.getTitle());
viewHolder.setDesc(model.getDesc());
viewHolder.setImage(getApplicationContext(), model.getImage());
viewHolder.setUsername(model.getUsername());
viewHolder.setUserImage(getApplicationContext(), model.getUserimage());
viewHolder.setLikeBtn(post_key);
viewHolder.mView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//Toast.makeText(MainActivity.this, "View clicked", Toast.LENGTH_SHORT).show();
Intent singleNotesIntent = new Intent(MainActivity.this, NotesSingleActivity.class);
singleNotesIntent.putExtra("notes_id", post_key);
startActivity(singleNotesIntent);
}
});
viewHolder.mLikebtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mProcessLike = true;
mDatabaseLike.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (mProcessLike) {
if (dataSnapshot.child(post_key).hasChild(auth.getCurrentUser().getUid())) {
mDatabaseLike.child(post_key).child(auth.getCurrentUser().getUid()).removeValue();
mProcessLike = false;
} else {
mDatabaseLike.child(post_key).child(auth.getCurrentUser().getUid()).setValue("ramdom");
mProcessLike = false;
}
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
});
}
};
mNotesList.setAdapter(firebaseRecyclerAdapter);
}
private void checkUserExist() {
if (auth.getCurrentUser() != null) {
final String user_id = auth.getCurrentUser().getUid();
mDatabaseUsers.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (!dataSnapshot.hasChild(user_id)) {
Intent setupIntent = new Intent(MainActivity.this, SetupActivity.class);
setupIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(setupIntent);
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}else {
startActivity(new Intent(MainActivity.this, AccountActivity.class));
}
}
public static class NotesViewHolder extends RecyclerView.ViewHolder {
View mView;
ImageButton mLikebtn;
DatabaseReference mDatabaseLike;
FirebaseAuth mAuth;
public NotesViewHolder(View itemView) {
super(itemView);
mView = itemView;
mLikebtn = (ImageButton) mView.findViewById(R.id.like_button);
mAuth = FirebaseAuth.getInstance();
mDatabaseLike = FirebaseDatabase.getInstance().getReference().child("Likes");
mDatabaseLike.keepSynced(true);
}
public void setLikeBtn(final String post_key) {
if (mAuth.getCurrentUser() != null) {
mDatabaseLike.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.child(post_key).hasChild(mAuth.getCurrentUser().getUid())) {
mLikebtn.setImageResource(R.drawable.like_it_48p);
} else {
mLikebtn.setImageResource(R.drawable.like_it_48);
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
}
public void setDate(String date) {
TextView notes_date = (TextView) mView.findViewById(R.id.notes_date);
notes_date.setText(date);
}
public void setTime(String time) {
TextView notes_time = (TextView) mView.findViewById(R.id.notes_time);
notes_time.setText(time);
}
public void setTitle(String title) {
TextView notes_title = (TextView) mView.findViewById(R.id.notes_title);
notes_title.setText(title);
}
public void setDesc(String desc) {
TextView notes_desc = (TextView) mView.findViewById(R.id.notes_desc);
notes_desc.setText(desc);
}
public void setUsername(String username) {
TextView notes_username = (TextView) mView.findViewById(R.id.notes_username);
notes_username.setText(username);
}
public void setUserImage(final Context context, final String image) {
final ImageView user_image = (ImageView) mView.findViewById(R.id.notes_userimage);
// Load image from offline first
Glide.with(context).load(image).fitCenter().diskCacheStrategy(DiskCacheStrategy.ALL).into(user_image);
}
public void setImage(final Context context, final String image) {
final ImageView notes_image = (ImageView) mView.findViewById(R.id.notes_image);
// Load image from offline first
Glide.with(context).load(image).fitCenter().diskCacheStrategy(DiskCacheStrategy.ALL).into(notes_image);
}
}
@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.main, menu);
MenuItem item = menu.findItem(R.id.action_image);
item.setVisible(false);
MenuItem item2 = menu.findItem(R.id.action_share);
item2.setVisible(false);
MenuItem item3 = menu.findItem(R.id.action_delete);
item3.setVisible(false);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_search) {
return true;
}
//noinspection SimplifiableIfStatement
if (id == R.id.action_logout) {
logout();
return true;
}
if (item.getItemId() == R.id.action_my_post) {
startActivity(new Intent(MainActivity.this, MyNotesActivity.class));
}
if (item.getItemId() == R.id.action_private_post) {
startActivity(new Intent(MainActivity.this, PrivateNotesActivity.class));
}
return super.onOptionsItemSelected(item);
}
private void logout() {
AuthUI.getInstance()
.signOut(this)
.addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
Log.d("AUTH", "USER LOGGED OUT!");
finish();
;
}
});
}
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
if (id == R.id.nav_account) {
// Handle the camera action
Intent intent = new Intent(this, AccountActivity.class);
startActivity(intent);
// Handle shared notes action
} else if (id == R.id.nav_shared_notes) {
Intent intent = new Intent(this, MyNotesActivity.class);
startActivity(intent);
// Handle private notes action
} else if (id == R.id.nav_private_notes) {
Intent intent = new Intent(this, PrivateNotesActivity.class);
startActivity(intent);
// Handle the Data action
} else if (id == R.id.nav_data) {
Intent intent = new Intent(this, DataActivity.class);
startActivity(intent);
// Handle the Reminders action
} else if (id == R.id.nav_reminders) {
Intent intent = new Intent(this, RemindersActivity.class);
startActivity(intent);
// Handle the help action
} else if (id == R.id.nav_help) {
Intent intent = new Intent(this, HelpActivity.class);
startActivity(intent);
// Handle the upgrade action
} else if (id == R.id.nav_upgrade) {
Intent intent = new Intent(this, UpgradeActivity.class);
startActivity(intent);
// Handle the logout action
} else if (id == R.id.nav_logout) {
Intent intent = new Intent(this, LogoutActivity.class);
startActivity(intent);
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.fab:
startActivity(new Intent(MainActivity.this, EntryEditActivity.class));
break;
case R.id.fab_chat:
startActivity(new Intent(MainActivity.this, ChatActivity.class));
break;
}
}
}
1楼
您可以使用以下示例：
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/emptyView"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<android.support.v7.widget.RecyclerView
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>
内部适配器：
@Override
public int getItemCount() {
if (mItems.size() == 0) {
mRecyclerView.setVisibility(View.INVISIBLE);
} else {
mRecyclerView.setVisibility(View.VISIBLE);
}
return mItems.size();
}
2楼
您还可以使用跟随并设置其高度。
<View
android:id="@+id/emptyview"
android:layout_width="match_parent"
android:layout_height="40dp"
/>