Question

我想写几封信件,我与一些事情一样,按期进行。

对每几分钟更新一次的URL投票似乎是一个相当常见的使用案例。然而,在这种特殊情况下,我只是试图一锁。

这项工作:

@Composable
fun App() {
    var ticks by remember { mutableStateOf(0) }

    // Not 100% happy about this unused variable either
    val timer = remember {
        Timer().apply {
            val task = object : TimerTask() {
                override fun run() {
                    ticks++
                }
            }
            scheduleAtFixedRate(task, 1000L, 1000L)
        }
    }

    MaterialTheme {
        Text(
            // A real application would format this number properly,
            // but that s a different question
            text = "$ticks"
        )
    }
}

但我不得不进口<代码>java.util。时间,因此不会有。

喷气池可以做一im,因此,它肯定有自己的时间,有些地方<>,这意味着也应当有某种可行的办法这样做,但我似乎无法看到这一点。

是否有跨平台的途径为此目的获得一个时间?

Answer 1

在对您进行认证时,可使用<条码>。

var ticks by remember { mutableStateOf(0) }
LaunchedEffect(Unit) {
    while(true) {
        delay(1.seconds)
        ticks++
    }
}

Answer 2

我只想谈谈我尝试的另一种做法,即有人想这样做,并遇到我同样的问题。这里是阴险的:

@Composable
fun Countdown(targetTime: Long, content: @Composable (remainingTime: Long) -> Unit) {
    var remainingTime by remember(targetTime) {
        mutableStateOf(targetTime - System.currentTimeMillis())
    }

    content.invoke(remainingTime)

    LaunchedEffect(remainingTime) {
        delay(1_000L)
        remainingTime = targetTime - System.currentTimeMillis()
    }
}

假设你想要达到第二位,则该分机将产生<条码>不适用,以更新<条码>后第二版<> 保留时间,更新<条码> 保留时间,与当前时段相比。这基本上造成了一种 lo。在@Composable中删除这一逻辑是好的,因为如果你在大树中填入了,这将防止这种过度再配。

This works, but there is a catch: you will eventually notice your timer is skipping seconds. This happens because there will be some extra delay between the assignment of a new value to the remainingTime variable and the re-execution of LaunchedEffect which will essentially mean there is more than a second between updates.

下面是上述工作的改进:

@Composable
fun Countdown(targetTime: Long, content: @Composable (remainingTime: Long) -> Unit) {
    var remainingTime by remember(targetTime) {
        mutableStateOf(targetTime - System.currentTimeMillis())
    }

    content.invoke(remainingTime)

    LaunchedEffect(remainingTime) {
        val diff = remainingTime - (targetTime - System.currentTimeMillis())
        delay(1_000L - diff)
        remainingTime = targetTime - System.currentTimeMillis()
    }
}

我们只是从预定的延迟时间中减去了填入“密码”的时间。这样做将避免你超时的 second。

额外的拖延不应成为在接受的答复中执行的问题。我注意到的这种做法的唯一好处是,一旦我们从屏幕上脱掉,就停止了。在我的测试中,尽管有<代码>true的条件,但在接触另一活动时仍保持正常。

Answer 3

@Composable
fun TimerTicks(
    initTick: Long = 1_000L,
    interval: Long = 1_000L,
    content: @Composable (tickTime: Long) -> Unit
) {

    var ticks by remember(initTick) {
        mutableStateOf(initTick)
    }

    content.invoke(ticks)

    LaunchedEffect(ticks) {
        val diff = ticks + interval
        delay(interval)
        ticks = diff
    }
}

Answer 4

Try this

@Composable
fun TimerScreen() {
    val timerConverter = remember {
        mutableStateOf("")
    }
    val lastConnection = remember {
        mutableStateOf(System.currentTimeMillis())
    }
    LaunchedEffect(key1 = timerConverter.value) {
        delay(1000)
        timerConverter.value =
            converting(1000 * 60 * 60 * 12L - (System.currentTimeMillis() - lastConnection.value))
    }
    Column(
        modifier = Modifier
            .fillMaxSize()
            .background(MaterialTheme.colorScheme.background)
    ) {

        Text(
            modifier = Modifier
                .fillMaxWidth()
                .padding(
                    top = 15.dp,
                    bottom = 10.dp,
                ),
            text = timerConverter.value,
            style = TextStyle(
                textAlign = TextAlign.Center,
                fontWeight = FontWeight.ExtraBold,
                fontSize = 25.sp,
                color = MaterialTheme.colorScheme.onBackground
            )
        )
    }
}

fun converting(millis: Long): String =
    String.format(
        "Hours %02d : Minutes %02d : Seconds %02d",
        TimeUnit.MILLISECONDS.toHours(millis),
        TimeUnit.MILLISECONDS.toMinutes(millis) - TimeUnit.HOURS.toMinutes(
            TimeUnit.MILLISECONDS.toHours(millis)
        ),
        TimeUnit.MILLISECONDS.toSeconds(millis) - TimeUnit.MINUTES.toSeconds(
            TimeUnit.MILLISECONDS.toMinutes(millis)
        )
    )

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