Jetpack compose view model

MainActivity.kt

package com.example.myapplication

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.activity.enableEdgeToEdge
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.padding
import androidx.compose.material3.Button
import androidx.compose.material3.Scaffold
import androidx.compose.material3.Text
import androidx.compose.runtime.getValue
import androidx.compose.ui.Modifier
import androidx.lifecycle.ViewModel
import androidx.lifecycle.compose.collectAsStateWithLifecycle
import androidx.lifecycle.viewmodel.compose.viewModel
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.asStateFlow
import kotlinx.coroutines.flow.update

data class CounterUiState(val value: Int)

class CounterViewModel : ViewModel() {

    private val _uiState = MutableStateFlow(CounterUiState(value = 0))
    val uiState: StateFlow<CounterUiState> = _uiState.asStateFlow()

    fun increase() {
        _uiState.update { currentState ->
            currentState.copy(
                value = currentState.value + 1,
            )
        }
    }
}

class MainActivity : ComponentActivity() {

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

        setContent {
            Scaffold { innerPadding ->
                val viewModel: CounterViewModel = viewModel()
                val uiState by viewModel.uiState.collectAsStateWithLifecycle()

                Column(modifier = Modifier.padding(innerPadding)) {
                    Button(
                        onClick = {
                            viewModel.increase()
                        }
                    ) {
                        Text("Increase")
                    }
                    Text(text = uiState.value.toString())
                }
            }
        }
    }
}