java.lang.RuntimeException: Can't toast on a thread that has not called Looper.prepare()

报错信息

java.lang.RuntimeException: Can't toast on a thread that has not called Looper.prepare()
        at android.widget.Toast$TN.(Toast.java:393)
        at android.widget.Toast.(Toast.java:117)
        at android.widget.Toast.makeText(Toast.java:280)
        at android.widget.Toast.makeText(Toast.java:270)

背景介绍

在后台的一个线程中调用 toast报错.

解决方案

toast("xxx")

修改为:

runOnUiThread {
    toast("xxx")
}