HomeFragment.java

package com.codewithharry.firebase;

import android.content.Intent;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.SearchView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.core.view.MenuItemCompat;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.codewithharry.firebase.adapters.AdapterPost;
import com.codewithharry.firebase.models.ModelPost;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;

import java.util.ArrayList;

public class HomeFragment extends Fragment {

    //FireBase aUth
    FirebaseAuth firebaseAuth;

    RecyclerView recyclerView;
    ArrayList<ModelPost> postList;
    AdapterPost adapterPosts;

    public HomeFragment() {
        // Required empty public constructor
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_home, container, false);

        //init
        firebaseAuth = FirebaseAuth.getInstance();

        //recycler view and its properties
        recyclerView = view.findViewById(R.id.postsRecyclerView);
        LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
        //show newest post first, for this load from last
        layoutManager.setStackFromEnd(true);
        layoutManager.setReverseLayout(true);
        //set layout recycler view
        recyclerView.setLayoutManager(layoutManager);

        //init post list
        postList = new ArrayList<>();

        loadPosts();

        return view;
    }

    private void loadPosts() {

        //path of all posts
        DatabaseReference ref = FirebaseDatabase.getInstance().getReference("Posts");
        //get all data from this ref
        ref.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                postList.clear();
                for (DataSnapshot ds : dataSnapshot.getChildren()) {
                    ModelPost modelPost = ds.getValue(ModelPost.class);

                    postList.add(modelPost);

                }
                //adapter
                adapterPosts = new AdapterPost(getActivity(), postList);
                //set adapter to recyclerview
                recyclerView.setAdapter(adapterPosts);
            }

            @Override
            public void onCancelled(@NonNull DatabaseError error) {
                //in case of error
                Toast.makeText(getActivity(), "" + error.getMessage(), Toast.LENGTH_SHORT).show();
            }
        });

    }

    private void searchPosts(String searchQuery) {


        //path of all posts
        DatabaseReference ref = FirebaseDatabase.getInstance().getReference("Posts");
        //get all data from this ref
        ref.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                postList.clear();
                for (DataSnapshot ds : dataSnapshot.getChildren()) {
                    ModelPost modelPost = ds.getValue(ModelPost.class);

                    if (modelPost.getpTitle().toLowerCase().contains(searchQuery.toLowerCase())
                            || modelPost.getpDescr().toLowerCase().contains(searchQuery.toLowerCase())) {
                        postList.add(modelPost);
                    }

                    //adapter
                    adapterPosts = new AdapterPost(getActivity(), postList);
                    //set adapter to recyclerview
                    recyclerView.setAdapter(adapterPosts);
                }
            }

            @Override
            public void onCancelled(@NonNull DatabaseError error) {
                //in case of error
                Toast.makeText(getActivity(), "" + error.getMessage(), Toast.LENGTH_SHORT).show();
            }
        });

    }

    private void checkUserStatus() {
        //Get current user
        FirebaseUser user = firebaseAuth.getCurrentUser();
        if (user != null) {
            //User is signed in stay here
            //set email of logged in user
            //mProfileTv.setText(user.getEmail());
        } else {
            //User not signed in go to main activity
            startActivity(new Intent(getActivity(), MainActivity.class));
            getActivity().finish();
        }
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        setHasOptionsMenu(true);//to show menu options in fragments
        super.onCreate(savedInstanceState);
    }

    /*Inflate options menu*/

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        inflater.inflate(R.menu.menu_main, menu);

        //search view to search posts by post title/description
        MenuItem item = menu.findItem(R.id.action_search);
        SearchView searchView = (SearchView) MenuItemCompat.getActionView(item);

        //search listener
        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                //called when user presses search button
                if (!TextUtils.isEmpty(query)) {
                    searchPosts(query);
                } else {
                    loadPosts();
                }
                return false;
            }

            @Override
            public boolean onQueryTextChange(String newText) {
                //called as and when user presses any letter
                if (!TextUtils.isEmpty(newText)) {
                    searchPosts(newText);
                } else {
                    loadPosts();
                }
                return false;
            }
        });

        super.onCreateOptionsMenu(menu, inflater);
    }

    /*Handle menu item clicks*/

    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
        //get item id
        int id = item.getItemId();
        if (id == R.id.action_logout) {
            firebaseAuth.signOut();
            checkUserStatus();
        }

        if (id == R.id.action_add_post) {
            startActivity(new Intent(getActivity(), AddPostActivity.class));
        }

        return super.onOptionsItemSelected(item);
    }

}