অ্যান্ড্রয়েডে ডাটাবেস সহ RecyclerView কীভাবে ব্যবহার করবেন?

SQLite ডাটাবেস + RecyclerView + CRUD অপারেশন

এই সমৃদ্ধ টিউটোরিয়ালটি দেখায় কীভাবে SQLite ডাটাবেস, RecyclerView, CardView এবং Material Design কম্পোনেন্টস ব্যবহার করে সম্পূর্ণ কন্টাক্ট ম্যানেজমেন্ট অ্যাপ বানানো যায়।

ধাপ ১: Dependencies (build.gradle)

dependencies {
    implementation "androidx.recyclerview:recyclerview:1.3.2"
    implementation "androidx.cardview:cardview:1.0.0"
    implementation "com.google.android.material:material:1.11.0"
    implementation "androidx.appcompat:appcompat:1.6.1"
}

ধাপ ২: লেআউট (activity_main.xml) - FAB সহ

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="https://schemas.android.com/apk/res/android"
    xmlns:tools="https://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="4dp"
    tools:context=".MainActivity">
    
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/myContactList"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginBottom="80dp"
        android:paddingBottom="8dp" />
    
    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/btnAdd"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="16dp"
        android:contentDescription="Add Contact"
        android:src="@android:drawable/ic_input_add" />
        
</FrameLayout>

ধাপ ৩: ডায়ালগ লেআউট (res/layout/add_contacts.xml)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:padding="16dp">
    
    <com.google.android.material.textfield.TextInputLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        style="@style/Widget.Material3.TextInputLayout.OutlinedBox">
        
        <com.google.android.material.textfield.TextInputEditText
            android:id="@+id/enterName"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="নাম লিখুন"
            android:inputType="text"
            android:maxLines="1" />
            
    </com.google.android.material.textfield.TextInputLayout>
    
    <com.google.android.material.textfield.TextInputLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        style="@style/Widget.Material3.TextInputLayout.OutlinedBox">
        
        <com.google.android.material.textfield.TextInputEditText
            android:id="@+id/enterPhoneNum"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="ফোন নম্বর"
            android:inputType="phone"
            android:maxLines="1" />
            
    </com.google.android.material.textfield.TextInputLayout>
</LinearLayout>

ধাপ ৪: আইটেম লেআউট (res/layout/contact_list_layout.xml)

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="https://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginBottom="8dp"
    android:layout_marginHorizontal="8dp"
    app:cardCornerRadius="12dp"
    app:cardElevation="4dp">
    
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:padding="16dp">
        
        <RelativeLayout
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1">
            <TextView
                android:id="@+id/contactName"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textSize="16sp"
                android:textStyle="bold"
                android:textColor="#212121" />
            <TextView
                android:id="@+id/phoneNum"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@id/contactName"
                android:layout_marginTop="4dp"
                android:textSize="14sp"
                android:textColor="#757575" />
        </RelativeLayout>
        
        <ImageView
            android:id="@+id/editContact"
            android:layout_width="24dp"
            android:layout_height="24dp"
            android:layout_gravity="center_vertical"
            android:layout_marginHorizontal="8dp"
            android:src="@drawable/ic_edit"
            android:contentDescription="Edit" />
            
        <ImageView
            android:id="@+id/deleteContact"
            android:layout_width="24dp"
            android:layout_height="24dp"
            android:layout_gravity="center_vertical"
            android:src="@drawable/ic_delete"
            android:contentDescription="Delete" />
            
    </LinearLayout>
</androidx.cardview.widget.CardView>

ধাপ ৫: মডেল (Contacts.java)

package com.app.sample;

public class Contacts {
    private int id;
    private String name;
    private String phoneNumber;

    public Contacts(String name, String phno) {
        this.name = name;
        this.phoneNumber = phno;
    }

    public Contacts(int id, String name, String phno) {
        this.id = id;
        this.name = name;
        this.phoneNumber = phno;
    }

    public int getId() { return id; }
    public void setId(int id) { this.id = id; }
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public String getPhno() { return phoneNumber; }
    public void setPhno(String phno) { this.phoneNumber = phno; }
}

ধাপ ৬: ViewHolder (ContactViewHolder.java)

package com.app.sample;

import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.recyclerview.widget.RecyclerView;

class ContactViewHolder extends RecyclerView.ViewHolder {
    TextView tvName, tvPhoneNum;
    ImageView deleteContact, editContact;

    ContactViewHolder(View itemView) {
        super(itemView);
        tvName = itemView.findViewById(R.id.contactName);
        tvPhoneNum = itemView.findViewById(R.id.phoneNum);
        deleteContact = itemView.findViewById(R.id.deleteContact);
        editContact = itemView.findViewById(R.id.editContact);
    }
}

ধাপ ৭: ডাটাবেস (SqliteDatabase.java)

package com.app.sample;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import java.util.ArrayList;

public class SqliteDatabase extends SQLiteOpenHelper {
    private static final int DATABASE_VERSION = 5;
    private static final String DATABASE_NAME = "ContactsDB";
    private static final String TABLE_CONTACTS = "Contacts";
    private static final String COLUMN_ID = "_id";
    private static final String COLUMN_NAME = "contactName";
    private static final String COLUMN_NO = "phoneNumber";

    SqliteDatabase(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "("
            + COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
            + COLUMN_NAME + " TEXT,"
            + COLUMN_NO + " TEXT" + ")";
        db.execSQL(CREATE_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);
        onCreate(db);
    }

    ArrayList<Contacts> listContacts() {
        ArrayList<Contacts> storeContacts = new ArrayList<>();
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery("SELECT * FROM " + TABLE_CONTACTS, null);
        
        if (cursor.moveToFirst()) {
            do {
                int id = cursor.getInt(cursor.getColumnIndexOrThrow(COLUMN_ID));
                String name = cursor.getString(cursor.getColumnIndexOrThrow(COLUMN_NAME));
                String phno = cursor.getString(cursor.getColumnIndexOrThrow(COLUMN_NO));
                storeContacts.add(new Contacts(id, name, phno));
            } while (cursor.moveToNext());
        }
        cursor.close();
        return storeContacts;
    }

    void addContacts(Contacts contacts) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(COLUMN_NAME, contacts.getName());
        values.put(COLUMN_NO, contacts.getPhno());
        db.insert(TABLE_CONTACTS, null, values);
    }

    void updateContacts(Contacts contacts) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(COLUMN_NAME, contacts.getName());
        values.put(COLUMN_NO, contacts.getPhno());
        db.update(TABLE_CONTACTS, values, COLUMN_ID + " = ?", 
            new String[]{String.valueOf(contacts.getId())});
    }

    void deleteContact(int id) {
        SQLiteDatabase db = this.getWritableDatabase();
        db.delete(TABLE_CONTACTS, COLUMN_ID + " = ?", 
            new String[]{String.valueOf(id)});
    }
}

ধাপ ৮: Adapter (ContactAdapter.java) - Filterable সহ

package com.app.sample;

import android.app.Activity;
import android.content.Context;
import android.content.DialogInterface;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
import android.widget.Filter;
import android.widget.Filterable;
import android.widget.Toast;
import androidx.appcompat.app.AlertDialog;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
import java.util.Objects;

class ContactAdapter extends RecyclerView.Adapter<ContactViewHolder> implements Filterable {
    private Context context;
    private ArrayList<Contacts> listContacts;
    private ArrayList<Contacts> mArrayList;
    private SqliteDatabase mDatabase;

    ContactAdapter(Context context, ArrayList<Contacts> listContacts) {
        this.context = context;
        this.listContacts = listContacts;
        this.mArrayList = new ArrayList<>(listContacts);
        mDatabase = new SqliteDatabase(context);
    }

    @Override
    public ContactViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.contact_list_layout, parent, false);
        return new ContactViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ContactViewHolder holder, int position) {
        Contacts contacts = listContacts.get(position);
        holder.tvName.setText(contacts.getName());
        holder.tvPhoneNum.setText(contacts.getPhno());
        
        holder.editContact.setOnClickListener(v -> editTaskDialog(contacts));
        
        holder.deleteContact.setOnClickListener(v -> {
            new AlertDialog.Builder(context)
                .setTitle("মুছুন?")
                .setMessage(contacts.getName() + " কি মুছতে চান?")
                .setPositiveButton("হ্যাঁ", (dialog, which) -> {
                    mDatabase.deleteContact(contacts.getId());
                    ((Activity) context).recreate(); // রিফ্রেশ
                })
                .setNegativeButton("না", null)
                .show();
        });
    }

    @Override
    public Filter getFilter() {
        return new Filter() {
            @Override
            protected FilterResults performFiltering(CharSequence constraint) {
                ArrayList<Contacts> filteredList = new ArrayList<>();
                if (constraint == null || constraint.length() == 0) {
                    filteredList.addAll(mArrayList);
                } else {
                    String filterPattern = constraint.toString().toLowerCase().trim();
                    for (Contacts item : mArrayList) {
                        if (item.getName().toLowerCase().contains(filterPattern)) {
                            filteredList.add(item);
                        }
                    }
                }
                FilterResults results = new FilterResults();
                results.values = filteredList;
                return results;
            }
            @Override
            protected void publishResults(CharSequence constraint, FilterResults results) {
                listContacts.clear();
                listContacts.addAll((ArrayList<Contacts>) results.values);
                notifyDataSetChanged();
            }
        };
    }

    @Override
    public int getItemCount() { return listContacts.size(); }

    private void editTaskDialog(Contacts contacts) {
        AlertDialog.Builder builder = new AlertDialog.Builder(context);
        View subView = LayoutInflater.from(context).inflate(R.layout.add_contacts, null);
        EditText nameField = subView.findViewById(R.id.enterName);
        EditText contactField = subView.findViewById(R.id.enterPhoneNum);
        
        nameField.setText(contacts.getName());
        contactField.setText(contacts.getPhno());
        
        builder.setTitle("কন্টাক্ট সম্পাদনা")
               .setView(subView)
               .setPositiveButton("আপডেট", (dialog, which) -> {
                   String name = nameField.getText().toString().trim();
                   String phno = contactField.getText().toString().trim();
                   if (TextUtils.isEmpty(name)) {
                       Toast.makeText(context, "নাম আবশ্যক", Toast.LENGTH_SHORT).show();
                   } else {
                       mDatabase.updateContacts(new Contacts(contacts.getId(), name, phno));
                       ((Activity) context).recreate();
                   }
               })
               .setNegativeButton("বাতিল", null)
               .show();
    }
}

ধাপ ৯: MainActivity.java - সব একসাথে

package com.app.sample;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
    private SqliteDatabase mDatabase;
    private ContactAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        RecyclerView contactView = findViewById(R.id.myContactList);
        contactView.setLayoutManager(new LinearLayoutManager(this));
        contactView.setHasFixedSize(true);
        
        mDatabase = new SqliteDatabase(this);
        loadContacts();
        
        FloatingActionButton btnAdd = findViewById(R.id.btnAdd);
        btnAdd.setOnClickListener(v -> addTaskDialog());
    }

    private void loadContacts() {
        ArrayList<Contacts> allContacts = mDatabase.listContacts();
        if (allContacts.isEmpty()) {
            Toast.makeText(this, "কোনো কন্টাক্ট নেই। যোগ করুন!", Toast.LENGTH_LONG).show();
        }
        adapter = new ContactAdapter(this, allContacts);
        RecyclerView contactView = findViewById(R.id.myContactList);
        contactView.setAdapter(adapter);
    }

    private void addTaskDialog() {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        View subView = LayoutInflater.from(this).inflate(R.layout.add_contacts, null);
        EditText nameField = subView.findViewById(R.id.enterName);
        EditText noField = subView.findViewById(R.id.enterPhoneNum);
        
        builder.setTitle("নতুন কন্টাক্ট যোগ করুন")
               .setView(subView)
               .setPositiveButton("যোগ করুন", (dialog, which) -> {
                   String name = nameField.getText().toString().trim();
                   String phno = noField.getText().toString().trim();
                   if (TextUtils.isEmpty(name)) {
                       Toast.makeText(this, "নাম লিখুন", Toast.LENGTH_SHORT).show();
                   } else {
                       mDatabase.addContacts(new Contacts(name, phno));
                       recreate();
                   }
               })
               .setNegativeButton("বাতিল", null)
               .show();
    }

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

আধুনিক আপগ্রেড: Room Database (সুপারিশড)

// build.gradle
implementation "androidx.room:room-runtime:2.6.1"
kapt "androidx.room:room-compiler:2.6.1"

// Entity
@Entity(tableName = "contacts")
data class Contact(
    @PrimaryKey(autoGenerate = true) val id: Int = 0,
    @ColumnInfo(name = "name") val name: String,
    @ColumnInfo(name = "phone") val phone: String
)

// DAO
@Dao
interface ContactDao {
    @Query("SELECT * FROM contacts ORDER BY name ASC")
    fun getAll(): LiveData<List<Contact>>
    
    @Insert(onConflict = OnConflictStrategy.REPLACE)
    suspend fun insert(contact: Contact)
    
    @Update
    suspend fun update(contact: Contact)
    
    @Delete
    suspend fun delete(contact: Contact)
    
    @Query("SELECT * FROM contacts WHERE name LIKE :query")
    fun search(query: String): LiveData<List<Contact>>
}

// Database
@Database(entities = [Contact::class], version = 1)
abstract class AppDatabase : RoomDatabase() {
    abstract fun contactDao(): ContactDao
}