我正在尝试运行 the simplest example with coroutines :
import kotlinx.coroutines.*
fun main() {
GlobalScope.launch {
delay(1000L)
println("${Thread.currentThread().name}: World")
}
println("${Thread.currentThread().name}: Hello")
Thread.sleep(2000L)
println("${Thread.currentThread().name}: Finish!")
}
我的 build.gradle 文件如下所示:
buildscript {
// Consider moving these values to `gradle.properties`
ext.kotlin_version = '1.3.0-rc-146'
ext.kotlin_gradle_plugin_version = '1.3.0-rc-198'
ext.kotlinx_coroutines = '1.0.0-RC1'
repositories {
maven { url "https://kotlin.bintray.com/kotlin-eap" }
mavenCentral()
jcenter()
google()
}
dependencies {
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.2.51"
}
}
plugins {
id 'org.jetbrains.kotlin.jvm' version "1.1.51"
}
apply plugin: 'idea'
apply plugin: 'application'
group 'by.kotlin'
version '1.0-SNAPSHOT'
mainClassName = 'MainKt'
repositories {
maven { url "https://kotlin.bintray.com/kotlin-eap" }
mavenCentral()
jcenter()
google()
}
dependencies {
implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
implementation "org.jetbrains.kotlin:kotlin-stdlib-common:$kotlin_version"
implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$kotlinx_coroutines"
}
compileKotlin {
kotlinOptions.jvmTarget = "1.8"
}
compileTestKotlin {
kotlinOptions.jvmTarget = "1.8"
}
但是当我运行这个例子时,我得到了以下错误:
e: ...Main.kt: (6, 17): 'launch(CoroutineContext = ..., CoroutineStart = ..., [ERROR : Bad suspend function in metadata with constructor: Function2]<CoroutineScope, Continuation<Unit>, Any?>): Job' is only available since Kotlin 1.3 and cannot be used in Kotlin 1.2
e: ...Main.kt: (7, 9): Suspend function 'delay' should be called only from a coroutine or another suspend function
e: ...Main.kt: (7, 9): 'delay(Long): Unit' is only available since Kotlin 1.3 and cannot be used in Kotlin 1.2
> Task :compileKotlin FAILED
为什么会出现这些错误?我完全糊涂了,因为第一个错误说启动“仅在 Kotlin 1.3 之后可用,不能在 Kotlin 1.2 中使用”,但我在 build.gradle 文件中使用 Kotlin 1.3(特别是 '1.3.0-rc -146')...
UPD
问题的原因似乎在 IntelliJ IDEA 设置中:
但是如果可以在那里选择的最新语言版本是 1.2,而不是 1.3,如何解决它?
最佳答案
确保您已将 Kotlin 更新到 1.3。您可以从 Preference->Lanugage & Framework->Kotlin Updates
然后在gradle中将kotlin.jvm
插件的版本改为1.3.0
。 (https://plugins.gradle.org/plugin/org.jetbrains.kotlin.jvm)
plugins {
id 'org.jetbrains.kotlin.jvm' version "1.3.0"
}
对于包含 coroutines
repositories {
mavenCentral()
}
dependencies {
compile group: 'org.jetbrains.kotlinx', name: 'kotlinx-coroutines-core', version: '1.0.0'
}
现在应该没问题了。
关于kotlin - launch 仅从 Kotlin 1.3 开始可用,不能在 Kotlin 1.2 中使用,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/53030756/