Exercise 5 11.03.2022 - Binding КОД ПРЕПОДАВАТЕЛ

import android.graphics.Color
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import androidx.databinding.DataBindingUtil
import com.example.upr5_binding.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {
    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        //setContentView(R.layout.activity_main)
        //binding=DataBindingUtil.setContentView(this, R.layout.activity_main)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)
        //binding.textView.text="Ok"
    }

    fun chetno(view: View)
    {
        val chislo=binding.editTextNumber.text.toString().toInt()
        if( chislo%2==0) {
            binding.textView.text="Четно"
            binding.textView.setBackgroundColor(Color.GREEN)
        } else {
            binding.textView.text="Нечетно"
            binding.textView.setBackgroundColor(Color.YELLOW)
        }
    }

    fun btn_oper(view: View) {
        var tel=binding.editTextPhone.text.toString()
        var nomer="None"
        if( tel.startsWith("359")) tel=tel.replace("359","0")
        // 35988 -> 088
        if( tel.startsWith("088") ) {
            binding.imageView.setImageResource(R.drawable.a1)
            //nomer="A1-"+tel.substring(3)
            nomer=tel.replace("088","A1-")
        } else
        if( tel.startsWith("087")) {
            binding.imageView.setImageResource(R.drawable.vivacom)
            //nomer="Vivacom-"+tel.substring(3)
            nomer=tel.replace("087","Vivacom-")
        } else
        if( tel.startsWith("089")) {
            binding.imageView.setImageResource(R.drawable.yettel)
            //nomer="Yettel-"+tel.substring(3)
            nomer=tel.replace("089","Yettel-")
        } else
            binding.imageView.setImageResource(R.drawable.vapros)
        binding.textView.text=nomer
    }
    // Въведено число в EditText, в TextView да се изведат броят на цифрите с думи
    // 34 -> двуцифрено,    123 -> трицифрено ...
    fun btn_zad(view: View) {
        //1
        /*val ch=binding.editTextNumber.text.toString()
        if( ch.length==1 )  binding.textView.text="Едноцифрено"
        if( ch.length==2 )  binding.textView.text="Двуоцифрено"
        if( ch.length==3 )  binding.textView.text="Трицифрено"
        if( ch.length>3 )  binding.textView.text="Многоцифрено"*/
        //2
        /*val ch=binding.editTextNumber.text.toString()
        when(ch.length) {
            1 ->binding.textView.text="Едноцифрено"
            2->binding.textView.text="Двуоцифрено"
            3->binding.textView.text="Трицифрено"
            else -> binding.textView.text="Многоцифрено"
        }*/
        //3
        val ch=binding.editTextNumber.text.toString()
        val vid= listOf("Многоцифрено","Едноцифрено","Двуоцифрено","Трицифрено")
        if(ch.length>3 ) binding.textView.text=vid[0]
        else binding.textView.text=vid[ch.length]
    }
}
<androidx.constraintlayout.widget.ConstraintLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/editTextNumber"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="37dp"
        android:layout_marginTop="27dp"
        android:layout_marginBottom="352dp"
        android:ems="10"
        android:inputType="number"
        app:layout_constraintBottom_toTopOf="@+id/imageView"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="45dp"
        android:layout_marginTop="32dp"
        android:onClick="btn_zad"
        android:text="Button"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editTextNumber" />

    <EditText
        android:id="@+id/editTextPhone"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="17dp"
        android:ems="10"
        android:inputType="phone"
        app:layout_constraintEnd_toEndOf="@+id/button2"
        app:layout_constraintStart_toEndOf="@+id/button2"
        app:layout_constraintTop_toBottomOf="@+id/button" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="53dp"
        android:layout_marginTop="28dp"
        android:onClick="btn_oper"
        android:text="Operator"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editTextPhone" />

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="269dp"
        android:layout_height="0dp"
        android:layout_marginStart="53dp"
        android:layout_marginBottom="118dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editTextNumber"
        app:srcCompat="@drawable/vapros" />

</androidx.constraintlayout.widget.ConstraintLayout>