android - Android Jetpack Compose 中数据类的更新策略

Question

我尝试使用数据类中的对象来更新 Composable 并将其声明如下:

data class CounterState(var counter: Int = 0)
.....
val counterState: CounterState by remember { mutableStateOf(CounterState(), structuralEqualityPolicy()) }

structuralEqualityPolicy() 是 Composable 的更新策略，定义如下:

A policy to treat values of a MutableState as equivalent if they arestructurally (==) equal.

如果属性计数器发生如下变化:counterState.counter++ 应该更新可组合项，但这不起作用。

我使用 Compose 版本 1.0.0-alpha06

知道如何解决这个问题吗？

import androidx.compose.foundation.Text
import androidx.compose.foundation.layout.Column
import androidx.compose.material.Button
import androidx.compose.runtime.*
import androidx.ui.tooling.preview.Preview

data class CounterState(var counter: Int = 0)

@Composable
fun dataClassRemember() {
    val counterState: CounterState by remember { mutableStateOf(CounterState(), structuralEqualityPolicy()) }
    Column() {
        Button(onClick = {
            counterState.counter++
        }) {
            Text(text = "Increment")
        }
        Text(text = "Counter value is ${counterState.counter}")
    }
}

@Preview("dataClassRemember")
@Composable
fun dataClassRememberPreview() {
    dataClassRemember()
}

Answer 1

我会试试这个:

data class CounterState(var counter: Int by remember { mutableStateOf(0)})

希望有用安娜