<string name="my_string">Showing your number: %1$s</string>

ActivityExt.kt

fun Activity.showToast(textResId: Int,vararg formatArgs: String) {
    val text = getString(textResId,formatArgs)
    Toast.makeText(this,text,Toast.LENGTH_SHORT).show()
}

MainActivity.kt

val number = 11
showToast(R.string.my_string,number.toString())

带有以下文字的吐司显示：

Showing your number: [Ljava.lang.String;@2cfa3b]

为什么会这样？