MainActivity. java
public class MainActivity extends AppCompatActivity {
RecyclerView recyclerView;
DatabaseReference reference;
FirebaseRecyclerAdapter<Bookdeets,Bkhomeholder>adapter;
FirebaseRecyclerOptions<Bookdeets> options;
ProgressBar loading;
FloatingActionButton searchbtn;
TextView logout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
reference = FirebaseDatabase.getInstance().getReference().child("books");
reference.keepSynced(true);
recyclerView = (RecyclerView) findViewById(R.id.rv);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.addItemDecoration(new DividerItemDecoration(this, LinearLayoutManager.VERTICAL));
loading=(ProgressBar)findViewById(R.id.loading);
searchbtn=(FloatingActionButton)findViewById(R.id.searchbtn);
logout = (TextView) findViewById(R.id.Logout);
logout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Logout();
}
});
searchbtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Opensearchpage();
}
});
options = new FirebaseRecyclerOptions.Builder<Bookdeets>()
.setQuery(reference, Bookdeets.class).build();
adapter = new FirebaseRecyclerAdapter<Bookdeets, Bkhomeholder>(options) {
@Override
protected void onBindViewHolder(@NonNull Bkhomeholder holder, int position, @NonNull Bookdeets model) {
Picasso.get().load(model.getImage()).into(holder.bookimg, new Callback() {
@Override
public void onSuccess() {
loading.setVisibility(View.GONE);
}
@Override
public void onError(Exception e) {
Toast.makeText(getApplicationContext(), "could not get the image", Toast.LENGTH_LONG).show();
loading.setVisibility(View.GONE);
}
});
holder.title.setText(model.getBookname());
}
@NonNull
@Override
public Bkhomeholder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.cardviewlay, parent, false);
return new Bkhomeholder(view);
}
};
GridLayoutManager gridLayoutManager=new GridLayoutManager(getApplicationContext(),3);
recyclerView.setLayoutManager(gridLayoutManager);
adapter.startListening();
recyclerView.setAdapter(adapter);
}
@Override
protected void onStart() {
super.onStart();
if(adapter!=null)
adapter.startListening();
loading.setVisibility(View.VISIBLE);
}
@Override
protected void onStop() {
super.onStop();
if(adapter!=null)
adapter.stopListening();
}
@Override
protected void onResume() {
super.onResume();
if(adapter!=null)
adapter.startListening();
}
public void Opensearchpage(){
Intent intent=new Intent(this, SearchPage.class);
startActivity(intent);
}
public void Logout() {
FirebaseAuth.getInstance().signOut();
startActivity(new Intent(getApplicationContext(), Login.class));
finish();
}
Бхомодержатель. java
public class Bkhomeholder extends RecyclerView.ViewHolder {
public TextView title;
public ImageView bookimg;
public Bkhomeholder(@NonNull View itemView) {
super(itemView);
title = itemView.findViewById(R.id.bkdettitle);
bookimg = itemView.findViewById(R.id.bkdetimg);
}
activity_main. xml
<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"
tools:context=".homepage.MainActivity"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="60dp"
android:layout_marginTop="4dp"
android:layout_marginStart="8dp"
android:layout_marginEnd="8dp"
android:text="Library App"
android:textAlignment="center"
android:textColor="#E21B1B"
android:textSize="32dp"
android:textStyle="bold" />
<androidx.recyclerview.widget.RecyclerView
android:clipChildren="true"
android:id="@+id/rv"
android:layout_width="match_parent"
android:layout_height="525dp"
android:layout_marginStart="8dp"
android:layout_marginTop="75dp"
android:layout_marginEnd="8dp"
android:layout_marginBottom="8dp"
android:clickable="true"
android:foreground="?android:attr/selectableItemBackground"/>
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="@+id/searchbtn"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_marginStart="345dp"
android:layout_marginTop="480dp"
android:layout_marginEnd="12dp"
android:background="#B3E5FC"
android:clickable="true"
app:srcCompat="@drawable/customicon" />
<ProgressBar
android:id="@+id/loading"
style="?android:attr/progressBarStyle"
android:layout_width="76dp"
android:layout_height="76dp"
android:layout_marginStart="163dp"
android:layout_marginTop="253dp"
android:layout_marginEnd="163dp"
android:layout_marginBottom="253dp"
android:visibility="invisible"
/>
<TextView
android:layout_width="match_parent"
android:layout_height="25dp"
android:id="@+id/Logout"
android:layout_centerHorizontal="true"
android:text="Logout"
android:textAlignment="center"
android:textSize="14sp"
android:layout_marginBottom="8dp"
android:layout_marginTop="565dp"
просмотр карты xml
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:cardview="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:clickable="true"
android:foreground="?android:attr/selectableItemBackground"
android:id="@+id/bookcardview"
android:layout_width="120dp"
android:layout_height="190dp"
android:layout_margin="5dp"
cardview:cardCornerRadius="4dp">
<LinearLayout
android:id="@+id/bkdetlinear"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:ignore="ExtraText"
android:clickable="true"
android:foreground="?android:attr/selectableItemBackground"
android:layout_marginEnd="4dp"
>
<ImageView
android:id="@+id/bkdetimg"
android:layout_width="match_parent"
android:layout_height="160dp"
android:background="#2d2d2d"
android:clickable="true"
android:scaleType="fitXY" />
<TextView
android:id="@+id/bkdettitle"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:text="Book title"
android:textColor="#2d2d2d"
android:textSize="12sp" />
</LinearLayout>
</androidx.cardview.widget.CardView>
</RelativeLayout>
я попытался установить щелчок на держателе карты, который является отдельным файлом xml, который надувается в моем mainacctivity, создать и установить прослушиватель onclick в onBindViewHolder, но я получил ошибку, связанную с нулевым указанием объекта, как если бы активность не могла обнаружить просмотр карты