[Android][Kotlin] MVVM & AAC 연습 예제

// Contact.kt

@Entity(tableName = "contact")
data class Contact(
    @PrimaryKey(autoGenerate = true)
    var id: Long?,

    @ColumnInfo(name = "name")
    var name: String,

    @ColumnInfo(name = "number")
    var number: String,

    @ColumnInfo(name = "initial")
    var initial: Char
) {
    constructor() : this(null, "", "", '\u0000')
}

// ContactDao.kt

@Dao
interface ContactDao {

    @Query("SELECT * FROM contact ORDER BY name ASC")
    fun getAll(): LiveData<List<Contact>>

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    fun insert(contact: Contact)

    @Delete
    fun delete(contact: Contact)

}

// ContactDatabase.kt

@Database(entities = [Contact::class], version = 1)
abstract class ContactDatabase: RoomDatabase() {

    abstract fun contactDao(): ContactDao

    companion object {
        private var INSTANCE: ContactDatabase? = null

        fun getInstance(context: Context): ContactDatabase? {
            if (INSTANCE == null) {
                synchronized(ContactDatabase::class) {
                    INSTANCE = Room.databaseBuilder(context.applicationContext,
                         ContactDatabase::class.java, "contact")
                        .fallbackToDestructiveMigration()
                        .build()
                }
            }
            return INSTANCE
        }
    }

}

// ContactRepository.kt
class ContactRepository(application: Application) {

    private val contactDatabase = ContactDatabase.getInstance(application)!!
    private val contactDao: ContactDao = contactDatabase.contactDao()
    private val contacts: LiveData<List<Contact>> = contactDao.getAll()

    fun getAll(): LiveData<List<Contact>> {
        return contacts
    }

    fun insert(contact: Contact) {
        try {
            val thread = Thread(Runnable {
                contactDao.insert(contact) })
            thread.start()
        } catch (e: Exception) { }
    }

    fun delete(contact: Contact) {
        try {
            val thread = Thread(Runnable {
                contactDao.delete(contact)
            })
            thread.start()
        } catch (e: Exception) { }
    }

}

// ContactViewModel.kt

class ContactViewModel(application: Application) : AndroidViewModel(application) {

    private val repository = ContactRepository(application)
    private val contacts = repository.getAll()

    fun getAll(): LiveData<List<Contact>> {
        return this.contacts
    }

    fun insert(contact: Contact) {
        repository.insert(contact)
    }

    fun delete(contact: Contact) {
        repository.delete(contact)
    }
}

// MainActivity.kt

class MainActivity : AppCompatActivity() {

    private lateinit var contactViewModel: ContactViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        contactViewModel = ViewModelProviders.of(this).get(ContactViewModel::class.java)
        contactViewModel.getAll().observe(this, Observer<List<Contact>> { contacts ->
                // Update UI
            })
    }

}

// ContactAdapter.kt

class ContactAdapter(val contactItemClick: (Contact) -> Unit, val contactItemLongClick: (Contact) -> Unit)
    : RecyclerView.Adapter<ContactAdapter.ViewHolder>() {
    private var contacts: List<Contact> = listOf()

    override fun onCreateViewHolder(parent: ViewGroup, i: Int): ViewHolder {
        val view = LayoutInflater.from(parent.context).inflate(R.layout.item_contact, parent, false)
        return ViewHolder(view)
    }

    override fun getItemCount(): Int {
        return contacts.size
    }

    override fun onBindViewHolder(viewHolder: ViewHolder, position: Int) {
        viewHolder.bind(contacts[position])
    }

    inner class ViewHolder(itemView: View): RecyclerView.ViewHolder(itemView) {
        private val nameTv = itemView.findViewById<TextView>(R.id.item_tv_name)
        private val numberTv = itemView.findViewById<TextView>(R.id.item_tv_number)
        private val initialTv = itemView.findViewById<TextView>(R.id.item_tv_initial)

        fun bind(contact: Contact) {
            nameTv.text = contact.name
            numberTv.text = contact.number
            initialTv.text = contact.initial.toString()

            itemView.setOnClickListener {
                contactItemClick(contact)
            }

            itemView.setOnLongClickListener {
                contactItemLongClick(contact)
                true
            }
        }
    }

    fun setContacts(contacts: List<Contact>) {
        this.contacts = contacts
        notifyDataSetChanged()
    }

}

// MainActivity.kt
class MainActivity : AppCompatActivity() {

    private lateinit var contactViewModel: ContactViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // Set contactItemClick & contactItemLongClick lambda
        val adapter = ContactAdapter({ contact ->
            // put extras of contact info & start AddActivity
        }, { contact ->
            deleteDialog(contact)
        })

        val lm = LinearLayoutManager(this)
        main_recycleview.adapter = adapter
        main_recycleview.layoutManager = lm
        main_recycleview.setHasFixedSize(true)

        contactViewModel = ViewModelProviders.of(this).get(ContactViewModel::class.java)
        contactViewModel.getAll().observe(this, Observer<List<Contact>> { contacts ->
                adapter.setContacts(contacts!!)
            })
    }

    private fun deleteDialog(contact: Contact) {
        val builder = AlertDialog.Builder(this)
        builder.setMessage("Delete selected contact?")
            .setNegativeButton("NO") { _, _ -> }
            .setPositiveButton("YES") { _, _ ->
                contactViewModel.delete(contact)
            }
        builder.show()
    }
}

// AddActivity.kt

class AddActivity : AppCompatActivity() {

    private lateinit var contactViewModel: ContactViewModel
    private var id: Long? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_add)

        contactViewModel = ViewModelProviders.of(this).get(ContactViewModel::class.java)

        // intent null check & get extras
        if (intent != null && intent.hasExtra(EXTRA_CONTACT_NAME) && intent.hasExtra(EXTRA_CONTACT_NUMBER)
            && intent.hasExtra(EXTRA_CONTACT_ID)) {
            add_edittext_name.setText(intent.getStringExtra(EXTRA_CONTACT_NAME))
            add_edittext_number.setText(intent.getStringExtra(EXTRA_CONTACT_NUMBER))
            id = intent.getLongExtra(EXTRA_CONTACT_ID, -1)
        }

        add_button.setOnClickListener {
            val name = add_edittext_name.text.toString().trim()
            val number = add_edittext_number.text.toString()

            if (name.isEmpty() || number.isEmpty()) {
                Toast.makeText(this, "Please enter name and number.", Toast.LENGTH_SHORT).show()
            } else {
                val initial = name[0].toUpperCase()
                val contact = Contact(id, name, number, initial)
                contactViewModel.insert(contact)
                finish()
            }
        }
    }

    companion object {
        const val EXTRA_CONTACT_NAME = "EXTRA_CONTACT_NAME"
        const val EXTRA_CONTACT_NUMBER = "EXTRA_CONTACT_NUMBER"
        const val EXTRA_CONTACT_ID = "EXTRA_CONTACT_ID"
    }
}

// MainActivity.kt

class MainActivity : AppCompatActivity() {

    private lateinit var contactViewModel: ContactViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // Set contactItemClick & contactItemLongClick lambda
        val adapter = ContactAdapter({ contact ->
            val intent = Intent(this, AddActivity::class.java)
            intent.putExtra(AddActivity.EXTRA_CONTACT_NAME, contact.name)
            intent.putExtra(AddActivity.EXTRA_CONTACT_NUMBER, contact.number)
            intent.putExtra(AddActivity.EXTRA_CONTACT_ID, contact.id)
            startActivity(intent)
        }, { contact ->
            deleteDialog(contact)
        })

        val lm = LinearLayoutManager(this)
        main_recycleview.adapter = adapter
        main_recycleview.layoutManager = lm
        main_recycleview.setHasFixedSize(true)

        contactViewModel = ViewModelProviders.of(this).get(ContactViewModel::class.java)
        contactViewModel.getAll().observe(this, Observer<List<Contact>> { contacts ->
                adapter.setContacts(contacts!!)
            })

        main_button.setOnClickListener {
            val intent = Intent(this, AddActivity::class.java)
            startActivity(intent)
        }
    }

    private fun deleteDialog(contact: Contact) {
        val builder = AlertDialog.Builder(this)
        builder.setMessage("Delete selected contact?")
            .setNegativeButton("NO") { _, _ -> }
            .setPositiveButton("YES") { _, _ ->
                contactViewModel.delete(contact)
            }
        builder.show()
    }
}