本文介绍了Kotlin MutableStateFlow.collect正在删除值的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有一个android应用程序，其中我正在尝试使用协程流使用我自己的事件总线库.设置MutableStateFlow的值然后收集到我的应用程序的代码中时，我看到丢弃的值.我创建了一个更简单的项目来演示相同的问题.关于为什么从MutableStateFlow中删除值的任何想法?
I have an android app in which I'm trying to use coroutine flows to replace the existing Otto EventBus using my own event bus library. I'm seeing dropped values when setting the MutableStateFlow's value and then collecting in my app's code. I've created a much simpler project that demonstrates the same issue. Any thoughts on why values are being dropped from the MutableStateFlow?
项目的build.gradle
Project's build.gradle
buildscript {
ext.kotlin_version = "1.4.10"
repositories {
google()
jcenter()
}
dependencies {
classpath "com.android.tools.build:gradle:4.0.1"
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
classpath 'com.google.gms:google-services:4.3.3'
classpath 'com.google.firebase:firebase-crashlytics-gradle:2.3.0'
classpath 'com.google.firebase:perf-plugin:1.3.1'
// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
}
}
allprojects {
repositories {
google()
jcenter()
}
}
task clean(type: Delete) {
delete rootProject.buildDir
}
应用程序模块的build.gradle
App Module's build.gradle
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'com.google.gms.google-services'
apply plugin: 'com.google.firebase.crashlytics'
apply plugin: 'com.google.firebase.firebase-perf'
android {
compileSdkVersion 29
buildToolsVersion "29.0.3"
defaultConfig {
applicationId "com.cren90.sandbox"
minSdkVersion 23
targetSdkVersion 29
versionCode 1
versionName "1.0"
testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
implementation fileTree(dir: "libs", include: ["*.jar"])
implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
implementation 'androidx.core:core-ktx:1.3.1'
implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.3.7'
implementation 'androidx.appcompat:appcompat:1.2.0'
implementation 'androidx.fragment:fragment:1.2.5'
implementation 'androidx.fragment:fragment-ktx:1.2.5'
implementation 'androidx.lifecycle:lifecycle-livedata-ktx:2.2.0'
implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.2.0'
implementation 'androidx.lifecycle:lifecycle-viewmodel:2.2.0'
implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'
implementation 'androidx.constraintlayout:constraintlayout:2.0.1'
implementation 'com.google.firebase:firebase-analytics:17.5.0'
implementation 'com.google.firebase:firebase-crashlytics:17.2.1'
implementation 'com.google.firebase:firebase-perf:19.0.8'
implementation 'com.google.firebase:firebase-messaging:20.2.4'
implementation 'com.jakewharton.timber:timber:4.7.1'
implementation 'androidx.legacy:legacy-support-v4:1.0.0'
implementation 'androidx.navigation:navigation-runtime:2.3.0'
implementation 'androidx.navigation:navigation-fragment:2.3.0'
implementation 'androidx.navigation:navigation-ui:2.3.0'
implementation 'androidx.navigation:navigation-runtime-ktx:2.3.0'
implementation 'androidx.navigation:navigation-fragment-ktx:2.3.0'
implementation 'androidx.navigation:navigation-ui-ktx:2.3.0'
testImplementation 'junit:junit:4.13'
androidTestImplementation 'androidx.test.ext:junit:1.1.2'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
}
MainActivity.kt
MainActivity.kt
package com.cren90.sandbox
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.navigation.findNavController
import kotlinx.android.synthetic.main.activity_main.*
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.collect
import kotlinx.coroutines.launch
import timber.log.Timber
import java.lang.RuntimeException
class MainActivity : AppCompatActivity() {
val flow: MutableStateFlow<Int> = MutableStateFlow<Int>(0)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
CoroutineScope(Dispatchers.IO).launch {
flow.collect {
Timber.d("cren90 - $it")
}
}
}
override fun onStart() {
super.onStart()
(application as SandboxApplication).apply {
startupTrace.putAttribute("APP_UUID", uuid)
startupTrace.stop()
}
}
override fun onResume() {
super.onResume()
for(i in 0..100) {
flow.value = i
}
}
}
我希望它能记录下来
2020-09-30 18:10:02.826 10533-10611/com.cren90.sandbox D/MainActivity$onCreate$1$invokeSuspend$$inlined$collect: cren90 - 0
2020-09-30 18:10:02.826 10533-10611/com.cren90.sandbox D/MainActivity$onCreate$1$invokeSuspend$$inlined$collect: cren90 - 1
2020-09-30 18:10:02.826 10533-10611/com.cren90.sandbox D/MainActivity$onCreate$1$invokeSuspend$$inlined$collect: cren90 - 2
...
2020-09-30 18:10:02.826 10533-10611/com.cren90.sandbox D/MainActivity$onCreate$1$invokeSuspend$$inlined$collect: cren90 - 98
2020-09-30 18:10:02.826 10533-10611/com.cren90.sandbox D/MainActivity$onCreate$1$invokeSuspend$$inlined$collect: cren90 - 99
2020-09-30 18:10:02.826 10533-10611/com.cren90.sandbox D/MainActivity$onCreate$1$invokeSuspend$$inlined$collect: cren90 - 100
但是它会记录
2020-09-30 18:10:02.826 10533-10611/com.cren90.sandbox D/MainActivity$onCreate$1$invokeSuspend$$inlined$collect: cren90 - 0
//Maybe 1 or 2 other random values in the 0-100 range
2020-09-30 18:10:02.826 10533-10611/com.cren90.sandbox D/MainActivity$onCreate$1$invokeSuspend$$inlined$collect: cren90 - 100
推荐答案
StateFlow官方文档指出:
StateFlow official documentation states:
您可以找到StateFlow官方文档此处.
You can find StateFlow official documentation here.
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