您的AppBar有一个名为.addOnOffsetChangedListener()的侦听器。
使用此侦听器将为您提供一种更简单的方法，同时使用屏幕滚动。
您可以使用偏移量来计算用户滚动是否等于侦听器提供的verticalOffset。
如果offset是0，则用户没有向下滚动屏幕，AppBar必须展开。
如果offset是not 0（负数），则用户必须向下滚动屏幕。
您可以遵循此实现：

// Your appbar, findViewById<AppBarLayout>(R.id....) should be used or binding
// You have to use your layout view and not initializing like this
val appbar = AppBarLayout(this)

// Variable to store when the appbar is collapsed or expanded
var isExpanded = false

// Variable to store the total scroll range
var scrollRange = -1

// Add a listener for the offset
appbar.addOnOffsetChangedListener(AppBarLayout.OnOffsetChangedListener { appBarLayout, verticalOffset ->
    // If the scrollRange has not been initialized
    if (scrollRange == -1) {
        // Set to the total scroll range
        scrollRange = appBarLayout.totalScrollRange
    }

    // If the scroll range + the verticalOffset == 0
    // If the sum result is 0 the appbar is expanded
    // If not, it must be collapsed
    if (scrollRange + verticalOffset == 0) {
        // The appbar is expanded
        isExpanded = true

        // Set the statusBar color when the appbar is expanded
        window.statusBarColor = getColor(R.color.red)

    // If the sum result is not 0 and it was previously expanded
    // Now it must be collapsed
    } else if (isExpanded) {
        // The appbar is collapsed
        isExpanded = false

        // Set the statusBar color when the appbar is collapsed
        window.statusBarColor = getColor(R.color.blue)
    }
})

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您可以在documentation中找到有关AppBarLayout的更多信息