LiveData + DataBinding 학습 예제

EditText로 값을 입력받고 버튼을 누르면

'저의 이름은 [이름]이고 [나이]살입니다!'라는 텍스트가 아래에 출력되도록 하였다.

 

1. MainActivity.kt

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding
    val liveUser = MutableLiveData<User>()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        binding = DataBindingUtil.setContentView(this, R.layout.activity_main)
        binding.apply {
            activity = this@MainActivity
            lifecycleOwner = this@MainActivity  //지정해주지 않으면 liveData가 실시간으로 변경되지 않음
        }

        binding.btnOk.setOnClickListener {
            //버튼을 누르면 EditText에서 값을 받아와서 liveData의 값을 바꿔준다.
            liveUser.value = User(binding.etName.text.toString(), binding.etAge.text.toString().toInt())
        }
    }
}

 

2. User.kt

class User(val name: String, val age: Int) {

}

3. activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<layout 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" >
    <data>
        <variable
            name="activity"
            type="com.monkey.databindingtest.MainActivity" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:padding="16dp"
        tools:context=".MainActivity">

        <TextView
            android:id="@+id/tv_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="이름"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintTop_toTopOf="@id/et_name"
            app:layout_constraintBottom_toBottomOf="@id/et_name"
            />
        <EditText
            android:id="@+id/et_name"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginLeft="16dp"
            app:layout_constraintLeft_toRightOf="@id/tv_name"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <TextView
            android:id="@+id/tv_age"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="나이"
            app:layout_constraintLeft_toLeftOf="@id/tv_name"
            app:layout_constraintTop_toTopOf="@id/et_age"
            app:layout_constraintBottom_toBottomOf="@id/et_age"
            />
        <EditText
            android:id="@+id/et_age"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:digits="0123456789"
            android:inputType="number"
            app:layout_constraintLeft_toLeftOf="@id/et_name"
            app:layout_constraintRight_toRightOf="@id/et_name"
            app:layout_constraintTop_toBottomOf="@id/et_name"
            />
        <Button
            android:id="@+id/btn_ok"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="introduce"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toBottomOf="@id/et_age"
            />

        <TextView
            android:id="@+id/tv_result"
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:background="#EAEAEA"
            android:text="@{`저의 이름은 ` + activity.liveUser.name + `이고 ` + activity.liveUser.age + `살 입니다!`}"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toBottomOf="@id/btn_ok"
            app:layout_constraintBottom_toBottomOf="parent"
            />
    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

 

실행 화면

 

참고 사이트

View Binding과 Data Binding 예제

LiveData(라이브 데이터)란?

 

 

[DataBinding/LiveData] 안드로이드 DataBinding과 LiveData 같이 사용하기

I want to concat two strings for a TextView in android, Data Binding Api