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Sirop4ik
Asked:2024-06-11 00:58:09 +0800 CST2024-06-11 00:58:09 +0800 CST

为什么会出现CompletionHandlerException？

  • 772

有Column一个按钮列表，您需要要求将焦点放在列表中的第一个按钮上，我是这样做的

...
               var modifier: Modifier = Modifier
                   .height(96.toDpWithOffset)
                   .width(520.toDpWithOffset)


               if (idx == 0) {
                   modifier = modifier.focusRequester(focusRequester)
               }

               Button(modifier = modifier...
...

也就是说，如果这是第一个按钮，则添加focusRequester到modifier

问题是这样的：视觉上它可以像这样缩短

...
                Button(
                    modifier = Modifier
                        .height(96.toDpWithOffset)
                        .width(520.toDpWithOffset)
                        .apply {
                            if (idx == 0) {
                                this.focusRequester(focusRequester)
                            }
                        }
...

但由于某种原因它会引发错误

Process: ca.bellmedia.cravetv.debug, PID: 27984
                 kotlinx.coroutines.CompletionHandlerException: Exception in completion handler InvokeOnCompletion@b5280d2[job@9cd05a3] for StandaloneCoroutine{Completed}@9cd05a3
                    at kotlinx.coroutines.JobSupport.completeStateFinalization(JobSupport.kt:322)
                    at kotlinx.coroutines.JobSupport.tryFinalizeSimpleState(JobSupport.kt:297)
                    at kotlinx.coroutines.JobSupport.tryMakeCompleting(JobSupport.kt:860)
                    at kotlinx.coroutines.JobSupport.makeCompletingOnce$kotlinx_coroutines_core(JobSupport.kt:832)
                    at kotlinx.coroutines.AbstractCoroutine.resumeWith(AbstractCoroutine.kt:100)
                    at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:46)
                    at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:108)
                    at androidx.compose.ui.platform.AndroidUiDispatcher.performTrampolineDispatch(AndroidUiDispatcher.android.kt:81)
                    at androidx.compose.ui.platform.AndroidUiDispatcher.access$performTrampolineDispatch(AndroidUiDispatcher.android.kt:41)
                    at androidx.compose.ui.platform.AndroidUiDispatcher$dispatchCallback$1.run(AndroidUiDispatcher.android.kt:57)
                    at android.os.Handler.handleCallback(Handler.java:958)
                    at android.os.Handler.dispatchMessage(Handler.java:99)
                    at android.os.Looper.loopOnce(Looper.java:205)
                    at android.os.Looper.loop(Looper.java:294)
                    at android.app.ActivityThread.main(ActivityThread.java:8177)
                    at java.lang.reflect.Method.invoke(Native Method)
                    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:552)
                    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:971)
                    Suppressed: kotlinx.coroutines.internal.DiagnosticCoroutineContextException: [androidx.compose.ui.platform.MotionDurationScaleImpl@99dc6cc, androidx.compose.runtime.BroadcastFrameClock@887fd15, StandaloneCoroutine{Completed}@9cd05a3, AndroidUiDispatcher@441582a]
                 Caused by: java.lang.IllegalStateException: 
                    FocusRequester is not initialized. Here are some possible fixes:
                 
                    1. Remember the FocusRequester: val focusRequester = remember { FocusRequester() }
                    2. Did you forget to add a Modifier.focusRequester() ?
                    3. Are you attempting to request focus during composition? Focus requests should be made in
                    response to some event. Eg Modifier.clickable { focusRequester.requestFocus() }

我在这里缺少什么？

android

1 个回答

  1. Best Answer

    尝试按如下方式重现您的代码

    @Composable
fun Test(
    rnd: Int
) {
    val focusRequest = remember { FocusRequester() }
    LaunchedEffect(rnd) {
        focusRequest.requestFocus()
    }
    Column {
        (0..3).forEach {i->
            TextField(
                modifier = Modifier
                    .let {
                        if (rnd == i) {
                            it.focusRequester(focusRequest)
                        } else it
                    },
                value = "${i}",
                onValueChange = {}
            )
        }
    }
}

    他工作。但如果你let用它替换它apply，它会崩溃并出现与你相同的错误。
    顺便说一句，这就是错误所说的
    2. Did you forget to add a Modifier.focusRequester() ?

    原因：所有方法Modifier'а都返回一个新对象，而不是向现有对象添加一些内容。使用let或任何其他方法会给你返回一个新的Modifier

    • 1

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