Looper.myLooper() == Looper.getMainLooper()

如果返回true，那么你在UI线程上!

只需记录这一行，它应该打印“main”。

Thread.currentThread () . name

简单的Toast消息也可以作为快速检查。

除了之前所有的答案

inline fun <T> ensureNotOnMainThread(block: () -> T): T {
    check(Thread.currentThread() != Looper.getMainLooper().thread) { "This function cannot be called on main thread" }
    return block()
}

允许用它包装任何方法，示例如下:

fun isInDataBase(id: String) = ensureNotOnMainThread { db.contains(id) }

一种基于协程的、与android无关的方法:

val onMainThread: Boolean
    get() = Thread.currentThread() === try {
        runBlocking(Dispatchers.Main.immediate) {
            Thread.currentThread()
        }
    } catch (e: IllegalStateException) {
        // No main dispatcher has been registered; not in an Android context?
        null
    }

Looper.myLooper() == Looper.getMainLooper()

如果返回true，那么你在UI线程上!