Android：在Recyclerview中滚动时设置搜索栏可见性

如何解决Android：在Recyclerview中滚动时设置搜索栏可见性

我想在Recyclerview中使用addOnScrollListener来设置如果列表向下滚动时搜索栏可见性，如果列表向上滚动则可见性消失。

施加条件dy> 0和dy

解决方法

 recyclerOverView.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrolled(RecyclerView recyclerView,int dx,int dy) {
            if (dy < 0)
                exFab.shrink();
            else if (dy > 0)
                exFab.extend();
        }

        @Override
        public void onScrollStateChanged(RecyclerView recyclerView,int newState) {
            super.onScrollStateChanged(recyclerView,newState);
        }
    });
}

检查它是否希望工作。

,

class MainActivity : AppCompatActivity() {
private val TAG = "MainActivity"
private val SEARCH_BAR_HEIGHT = dpToPx(70)  //replace it with view height

private val scrollListener = object : RecyclerView.OnScrollListener() {
    var isSearchVisible = false
    var isAnimating = false
    var lastPosition = -1
    var currentPosition = 0
    var isScrollingUp = false

    override fun onScrolled(recyclerView: RecyclerView,dx: Int,dy: Int) {
        currentPosition =
            (recyclerView.layoutManager as LinearLayoutManager).findFirstCompletelyVisibleItemPosition()
        Log.d(TAG,"current position = $currentPosition last Position = $lastPosition")

        if (currentPosition < lastPosition) {
            //scroll up
            if (!isScrollingUp || isSearchVisible || isAnimating) {
                isScrollingUp = true
                lastPosition = currentPosition
                return
            }

            isAnimating = true
            isScrollingUp = true

            animate(searchView,SEARCH_BAR_HEIGHT,object : AnimationListener {
                override fun onAnimationCompleted() {
                    isAnimating = false
                    isSearchVisible = true
                }

                override fun onAnimationCanceled() {
                    isAnimating = false
                }
            })
        } else if (currentPosition > lastPosition) {
            //scroll down
            if (isScrollingUp || !isSearchVisible || isAnimating) {
                isScrollingUp = false
                lastPosition = currentPosition
                return
            }

            isAnimating = true
            isScrollingUp = false
            animate(searchView,object : AnimationListener {
                override fun onAnimationCompleted() {
                    isAnimating = false
                    isSearchVisible = false
                    searchView.visibility = View.GONE
                }

                override fun onAnimationCanceled() {
                    isAnimating = false
                }
            })
        }
        lastPosition = currentPosition
    }
}

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main2)

    recyclerView.apply {
        layoutManager = LinearLayoutManager(this@MainActivity)
        adapter = ItemAdapter()
        addOnScrollListener(scrollListener)
    }
}

fun animate(view: View,fromHeight: Int,toHeight: Int,callback: AnimationListener?) {
    view.clearAnimation()
    view.visibility = View.VISIBLE
    val valueAnimator: ValueAnimator = ValueAnimator.ofInt(fromHeight,toHeight)

    valueAnimator.addUpdateListener { animation ->
        val layoutParam = view.layoutParams
        layoutParam.height = animation.animatedValue as Int
        view.layoutParams = layoutParam
    }

    valueAnimator.addListener(object : Animator.AnimatorListener {
        override fun onAnimationRepeat(p0: Animator?) {
        }

        override fun onAnimationEnd(p0: Animator?) {
            callback?.onAnimationCompleted()
        }

        override fun onAnimationCancel(p0: Animator?) {
            callback?.onAnimationCanceled()
        }

        override fun onAnimationStart(p0: Animator?) {
        }

    })

    valueAnimator.interpolator = DecelerateInterpolator()
    valueAnimator.duration = 200
    valueAnimator.start()
}

interface AnimationListener {
    fun onAnimationCompleted()
    fun onAnimationCanceled()
}

}