توسعه اپلیکیشن اندروید با Java و Kotlin

1. File → New → New Project
2. انتخاب Template مناسب
3. انتخاب زبان (Java یا Kotlin)
4. تنظیم نام و package name
5. انتخاب minimum SDK version

// Java
public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}

// Kotlin
class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }
}

// ProductDetailFragment.kt
class ProductDetailFragment : Fragment() {
    private var productId: String? = null
    private var product: Product? = null
    
    // Views
    private lateinit var productImage: ImageView
    private lateinit var productName: TextView
    private lateinit var productPrice: TextView
    private lateinit var productDescription: TextView
    private lateinit var addToCartButton: Button
    private lateinit var progressBar: ProgressBar
    
    // ViewModel
    private lateinit var viewModel: ProductViewModel
    
    companion object {
        private const val ARG_PRODUCT_ID = "product_id"
        
        fun newInstance(productId: String): ProductDetailFragment {
            val fragment = ProductDetailFragment()
            val args = Bundle()
            args.putString(ARG_PRODUCT_ID, productId)
            fragment.arguments = args
            return fragment
        }
    }
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        arguments?.let {
            productId = it.getString(ARG_PRODUCT_ID)
        }
        
        // Initialize ViewModel
        viewModel = ViewModelProvider(this)[ProductViewModel::class.java]
    }
    
    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        return inflater.inflate(R.layout.fragment_product_detail, container, false)
    }
    
    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        
        // Initialize views
        productImage = view.findViewById(R.id.product_image)
        productName = view.findViewById(R.id.product_name)
        productPrice = view.findViewById(R.id.product_price)
        productDescription = view.findViewById(R.id.product_description)
        addToCartButton = view.findViewById(R.id.add_to_cart_button)
        progressBar = view.findViewById(R.id.progress_bar)
        
        // Setup click listeners
        addToCartButton.setOnClickListener {
            product?.let { addToCart(it) }
        }
        
        // Observe ViewModel
        observeViewModel()
        
        // Load product data
        productId?.let { viewModel.loadProduct(it) }
    }
    
    private fun observeViewModel() {
        viewModel.product.observe(viewLifecycleOwner) { product ->
            this.product = product
            updateUI(product)
        }
        
        viewModel.isLoading.observe(viewLifecycleOwner) { isLoading ->
            progressBar.visibility = if (isLoading) View.VISIBLE else View.GONE
        }
        
        viewModel.error.observe(viewLifecycleOwner) { error ->
            error?.let {
                showError(it)
            }
        }
    }
    
    private fun updateUI(product: Product) {
        // Load image using Glide or similar library
        Glide.with(this)
            .load(product.imageUrl)
            .placeholder(R.drawable.placeholder)
            .error(R.drawable.error)
            .into(productImage)
        
        productName.text = product.name
        productPrice.text = "%,d تومان".format(product.price)
        productDescription.text = product.description
        
        addToCartButton.isEnabled = product.isAvailable
    }
    
    private fun addToCart(product: Product) {
        // Add to cart logic
        viewModel.addToCart(product)
        
        // Show success message
        Snackbar.make(requireView(), "محصول به سبد خرید اضافه شد", Snackbar.LENGTH_SHORT)
            .setAction("مشاهده سبد") {
                // Navigate to cart
                findNavController().navigate(R.id.action_to_cart)
            }
            .show()
    }
    
    private fun showError(error: String) {
        AlertDialog.Builder(requireContext())
            .setTitle("خطا")
            .setMessage(error)
            .setPositiveButton("تلاش مجدد") { _, _ ->
                productId?.let { viewModel.loadProduct(it) }
            }
            .setNegativeButton("بستن", null)
            .show()
    }
}

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 
    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"
    android:padding="16dp"
    tools:context=".MainActivity">

    <!-- App Bar -->
    <com.google.android.material.appbar.AppBarLayout
        android:id="@+id/app_bar"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent">
        
        <com.google.android.material.appbar.MaterialToolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:title="فروشگاه آنلاین"
            app:titleTextColor="@android:color/white" />
    </com.google.android.material.appbar.AppBarLayout>

    <!-- Search Bar -->
    <com.google.android.material.textfield.TextInputLayout
        android:id="@+id/search_layout"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        app:layout_constraintTop_toBottomOf="@id/app_bar"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:startIconDrawable="@drawable/ic_search"
        app:hint="جستجو در محصولات...">
        
        <com.google.android.material.textfield.TextInputEditText
            android:id="@+id/search_edit_text"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:inputType="text" />
    </com.google.android.material.textfield.TextInputLayout>

    <!-- Categories RecyclerView -->
    <TextView
        android:id="@+id/categories_label"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:text="دسته‌بندی‌ها"
        android:textAppearance="style=""/TextAppearance.MaterialComponents.Headline6"
        app:layout_constraintTop_toBottomOf="@id/search_layout"
        app:layout_constraintStart_toStartOf="parent" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/categories_recycler"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:orientation="horizontal"
        app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
        app:layout_constraintTop_toBottomOf="@id/categories_label"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        tools:listitem="@layout/item_category" />

    <!-- Products Grid -->
    <TextView
        android:id="@+id/products_label"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:text="محصولات پیشنهادی"
        android:textAppearance="style=""/TextAppearance.MaterialComponents.Headline6"
        app:layout_constraintTop_toBottomOf="@id/categories_recycler"
        app:layout_constraintStart_toStartOf="parent" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/products_recycler"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginTop="8dp"
        android:padding="4dp"
        app:layoutManager="androidx.recyclerview.widget.GridLayoutManager"
        app:spanCount="2"
        app:layout_constraintTop_toBottomOf="@id/products_label"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        tools:listitem="@layout/item_product" />

    <!-- Floating Action Button -->
    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fab_cart"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:src="@drawable/ic_shopping_cart"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:backgroundTint="@color/primary_color"
        app:tint="@android:color/white" />

    <!-- Loading Indicator -->
    <com.google.android.material.progressindicator.CircularProgressIndicator
        android:id="@+id/loading_indicator"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:visibility="gone"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

// ذخیره داده
val sharedPref = getSharedPreferences("my_prefs", Context.MODE_PRIVATE)
with(sharedPref.edit()) {
    putString("username", "علی")
    apply()
}

// خواندن داده
val username = sharedPref.getString("username", "")

@Entity
data class User(
    @PrimaryKey val id: Int,
    val name: String,
    val email: String
)

@Dao
interface UserDao {
    @Query("SELECT * FROM user")
    fun getAllUsers(): List<User>

    @Insert
    fun insertUser(user: User)
}