Android ViewModel 사용법

1. ViewModel Implementation 하기

• App 모듈의 build.gradle에 아래 내용을 추가하고 sync 합니다..

dependencies {
    implementation("androidx.lifecycle:lifecycle-viewmodel-ktx:2.6.2")
}

 

2. ViewModel 클래스 만들기

import androidx.lifecycle.ViewModel

class FlashlightViewModel: ViewModel() {
    val isFlashlightOn: Boolean = false
}

 

3. Activity에서 ViewModel 사용하기

class FlashlightActivity : AppCompatActivity() {

    private val viewModel: FlashlightViewModel by lazy {
        ViewModelProvider(this)[FlashlightViewModel::class.java]
    }

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

        Log.d("FlashlightActivity", "onCreate : ${viewModel.isFlashlightOn}")
    }
}