Java 如何在 Kotlin 中初始化线程？
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How to initialize a Thread in Kotlin?
提问by Shubhranshu Jain
In Java it works by accepting an object which implements runnable :
在 Java 中，它通过接受一个实现 runnable 的对象来工作：
Thread myThread = new Thread(new myRunnable())
where myRunnableis a class implementing Runnable.
哪里myRunnable是一个实现Runnable.
But when I tried this in Kotlin, it doesn't seems to work:
但是当我在 Kotlin 中尝试这个时，它似乎不起作用：
var myThread:Thread = myRunnable:Runnable
回答by Rajesh Dalsaniya
Runnable:
可运行：
val myRunnable = runnable {
}
Thread:
线：
Thread({
// call runnable here
println("running from lambda: ${Thread.currentThread()}")
}).start()
You don't see a Runnable here: in Kotlin it can easily be replaced with a lambda expression. Is there a better way? Sure! Here's how you can instantiate and start a thread Kotlin-style:
您在此处看不到 Runnable：在 Kotlin 中，它可以轻松地替换为 lambda 表达式。有没有更好的办法？当然！以下是如何实例化和启动 Kotlin 风格的线程：
thread(start = true) {
println("running from thread(): ${Thread.currentThread()}")
}
回答by s1m0nw1
For initialising an object of Threadyou simply invoke the constructor:
要初始化Thread您的对象，只需调用构造函数：
val t = Thread()
Then, you can also pass an optional Runnablewith a lambda (SAM Conversion) like this:
然后，您还可以Runnable像这样传递带有 lambda（SAM 转换）的可选项：
Thread {
Thread.sleep(1000)
println("test")
}
The more explicit version is passing an anonymous implementation of Runnablelike this:
更明确的版本是传递这样的匿名实现Runnable：
Thread(Runnable {
Thread.sleep(1000)
println("test")
})
Note that the previously shown examples do only createan instance of a Threadbut don't actually start it. In order to achieve that, you need to invoke start()explicitly.
请注意，前面显示的示例仅创建了 a 的实例，Thread但实际上并未启动它。为了实现这一点，您需要start()显式调用。
Last but not least, you need to know the standard library function thread, which I'd recommend to use:
最后但并非最不重要的一点是，您需要了解thread我建议使用的标准库函数：
public fun thread(start: Boolean = true, isDaemon: Boolean = false, contextClassLoader: ClassLoader? = null, name: String? = null, priority: Int = -1, block: () -> Unit): Thread {
You can use it like this:
你可以这样使用它：
thread(start = true) {
Thread.sleep(1000)
println("test")
}
It has many optional parameters for e.g. directly starting the thread as shown here. Note that trueis the default value of startanyway.
它有许多可选参数，例如直接启动线程，如下所示。请注意，这true是start无论如何的默认值。
回答by Hardeep singh
Please try this code:
请试试这个代码：
Thread().run { Thread.sleep(3000); }
回答by Alexey Soshin
Best way would be to use thread()generator function from kotlin.concurrent:
https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.concurrent/thread.html
最好的方法是使用以下thread()生成器函数kotlin.concurrent：https:
//kotlinlang.org/api/latest/jvm/stdlib/kotlin.concurrent/thread.html
You should check its default values, as they're quite useful:
您应该检查其默认值，因为它们非常有用：
thread() { /* do something */ }
Note that you don't need to call start()like in the Thread example, or provide start=true.
请注意，您不需要start()像 Thread 示例中那样调用，也不需要提供start=true.
Be careful with threads that run for a long period of time. It's useful to specify thread(isDaemon= true)so your application would be able to terminate correctly.
小心运行很长时间的线程。指定很有用，thread(isDaemon= true)以便您的应用程序能够正确终止。
回答by Adam Hurwitz
I did the following and it appears to be working as expected.
我做了以下操作，它似乎按预期工作。
Thread(Runnable {
//some method here
}).start()
回答by hgedek
fun main(args: Array<String>) {
Thread({
println("test1")
Thread.sleep(1000)
}).start()
val thread = object: Thread(){
override fun run(){
println("test2")
Thread.sleep(2000)
}
}
thread.start()
Thread.sleep(5000)
}
回答by Geet Thakur
Basic example of Threadwith Lamda
Threadwith的基本例子Lamda
fun main() {
val mylamda = Thread({
for (x in 0..10){
Thread.sleep(200)
println("$x")
}
})
startThread(mylamda)
}
fun startThread(mylamda: Thread) {
mylamda.start()
}
回答by David Callanan
thread { /* your code here */ }
回答by Coder
Firstly, create a function for set default propery
首先，创建一个设置默认属性的函数
fun thread(
start: Boolean = true,
isDaemon: Boolean = false,
contextClassLoader: ClassLoader? = null,
name: String? = null,
priority: Int = -1,
block: () -> Unit
): Thread
then perform background operation calling this function
然后执行调用此函数的后台操作
thread(start = true) {
//Do background tasks...
}
Or kotlin coroutines also can be used to perform background task
或者 kotlin 协程也可以用来执行后台任务
GlobalScope.launch {
//TODO("do background task...")
withContext(Dispatchers.Main) {
// TODO("Update UI")
}
//TODO("do background task...")
}
