MainActivity.kt
package com.cfsuman.composestate
import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.layout.*
import androidx.compose.material.*
import androidx.compose.runtime.*
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import androidx.lifecycle.viewmodel.compose.viewModel
import com.cfsuman.composestate.ui.theme.ComposeStateTheme
class MainActivity : ComponentActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContent {
ComposeStateTheme {
Scaffold(
topBar = { TopAppBar(
title = {
Text(text = "Compose - ViewModel State")
}
)},
content = { MainContent() },
backgroundColor = Color(0xFFEDEAE0)
)
}
}
}
}
@Composable
fun MainContent() {
val viewModel = viewModel<MyViewModel>()
val counter = viewModel.counter.collectAsState()
Column(
Modifier.fillMaxSize().padding(24.dp),
verticalArrangement = Arrangement.spacedBy(16.dp),
horizontalAlignment = Alignment.CenterHorizontally
) {
Text(text = "${counter.value}", fontSize = 40.sp)
Button(onClick = { viewModel.incrementCounter() }) {
Text(text = "Increment Counter")
}
}
}
MyViewModel.kt
package com.cfsuman.composestate
import androidx.lifecycle.ViewModel
import kotlinx.coroutines.flow.*
class MyViewModel:ViewModel() {
private val _counter = MutableStateFlow(0)
val counter = _counter.asStateFlow()
fun incrementCounter(){
_counter.value +=1
}
}
build.gradle [app]
dependencies {
implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.5.0-alpha06"
implementation "androidx.lifecycle:lifecycle-viewmodel-compose:2.5.0-alpha06"
}
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