telegram v.0.01 firebase android example

different files.java

MainActivity.java:

package site.sunmeat.helloworld;

import android.os.Bundle;
import android.widget.*;
import androidx.appcompat.app.AppCompatActivity;
import com.google.firebase.firestore.*;
import java.util.*;

public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";
    private static final String COLLECTION_NAME = "chat_messages";

    private FirebaseFirestore db;
    private ListView listView;
    private EditText editMessage;
    private TextView tvLogin;

    private ArrayList<String> messagesList;
    private ArrayAdapter<String> adapter;
    private ListenerRegistration listenerRegistration;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        db = FirebaseFirestore.getInstance();

        listView = findViewById(R.id.listView);
        editMessage = findViewById(R.id.editMessage);
        tvLogin = findViewById(R.id.tvLogin);
        ImageButton btnSend = findViewById(R.id.btnSend);

        tvLogin.setText("Sunmeat");

        messagesList = new ArrayList<>();
        adapter = new ArrayAdapter<>(this,
                android.R.layout.simple_list_item_1, messagesList);
        listView.setAdapter(adapter);

        btnSend.setOnClickListener(v -> sendMessage());

        editMessage.setOnEditorActionListener((v, actionId, event) -> {
            sendMessage();
            return true;
        });

        startListening();
    }

    private void sendMessage() {
        String login = tvLogin.getText().toString().replace("Ти: ", "").trim(); // беремо з TextView
        String message = editMessage.getText().toString().trim();

        if (login.isEmpty()) {
            Toast.makeText(this, "Зміни логін у верхньому полі", Toast.LENGTH_SHORT).show();
            return;
        }
        if (message.isEmpty()) {
            Toast.makeText(this, "Напиши повідомлення", Toast.LENGTH_SHORT).show();
            return;
        }

        Map<String, Object> data = new HashMap<>();
        data.put("login", login);
        data.put("message", message);
        data.put("timestamp", FieldValue.serverTimestamp());

        db.collection(COLLECTION_NAME)
                .add(data)
                .addOnSuccessListener(documentReference -> {
                    editMessage.setText(""); // очищаємо поле
                })
                .addOnFailureListener(e -> {
                    Toast.makeText(this, "Помилка: " + e.getMessage(), Toast.LENGTH_LONG).show();
                });
    }

    private void startListening() {
        listenerRegistration = db.collection(COLLECTION_NAME)
                .orderBy("timestamp", Query.Direction.ASCENDING)
                .addSnapshotListener((snapshots, e) -> {
                    if (e != null) {
                        Toast.makeText(this, "Помилка підключення: " + e.getMessage(), Toast.LENGTH_LONG).show();
                        return;
                    }

                    messagesList.clear();
                    assert snapshots != null;
                    for (QueryDocumentSnapshot doc : snapshots) {
                        String login = doc.getString("login");
                        String message = doc.getString("message");
                        if (login != null && message != null) {
                            messagesList.add(login + ": " + message);
                        }
                    }
                    adapter.notifyDataSetChanged();
                    listView.setSelection(messagesList.size() - 1);
                });
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (listenerRegistration != null) {
            listenerRegistration.remove();
        }
    }
}

=======================================================================================================================
  
activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FFFFFF"
    android:orientation="vertical">

    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:background="#F7F7F8"
        android:clipToPadding="false"
        android:divider="@android:color/transparent"
        android:dividerHeight="12dp"
        android:padding="12dp"
        android:stackFromBottom="true"
        android:transcriptMode="alwaysScroll" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#FFFFFF"
        android:elevation="4dp"
        android:orientation="vertical"
        android:paddingTop="12dp"
        android:paddingBottom="12dp">

        <TextView
            android:id="@+id/tvLogin"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="20dp"
            android:layout_marginBottom="6dp"
            android:text="Sunmeat"
            android:textColor="#777777"
            android:textSize="14sp"
            android:textStyle="italic" />

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginStart="16dp"
            android:layout_marginEnd="16dp"
            android:layout_marginBottom="8dp"
            android:background="#F0F2F5"
            android:backgroundTint="#F0F2F5"
            android:gravity="center_vertical"
            android:minHeight="50dp"
            android:orientation="horizontal"
            android:outlineAmbientShadowColor="#40000000"
            android:outlineSpotShadowColor="#40000000"
            android:padding="4dp">

            <EditText
                android:id="@+id/editMessage"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_marginStart="12dp"
                android:layout_weight="1"
                android:background="@null"
                android:hint="Напиши повідомлення..."
                android:imeOptions="actionSend"
                android:inputType="textCapSentences|textMultiLine|textShortMessage"
                android:maxLines="6"
                android:textColor="#000000"
                android:textColorHint="#888888"
                android:textSize="16sp" />

            <ImageButton
                android:id="@+id/btnSend"
                android:layout_width="48dp"
                android:layout_height="48dp"
                android:background="?android:attr/selectableItemBackgroundBorderless"
                android:contentDescription="Відправити"
                android:scaleType="centerInside"
                android:src="@android:drawable/ic_menu_send"
                app:tint="#0088CC" />

        </LinearLayout>
    </LinearLayout>
</LinearLayout>