Problems专题：RecyclerView

Problems专题：RecyclerView

0x01 Called attach on a child which is not detached

java.lang.IllegalArgumentException: Called attach on a child which is not detached: BaseViewHolder{2b241e1 position=12 id=-1, oldPos=-1, pLpos:-1} androidx.recyclerview.widget.RecyclerView{afecb06 VFED..... ......ID 0,0-1080,2055 #7f09236e app:id/recycler_view_xxx}, adapter:com.xxxx.adapter.XxxAdapter@cfc75c7, layout:androidx.recyclerview.widget.LinearLayoutManager@24af7f4, context:com.xxxx.XxxActivity@1ed75e2
	at androidx.recyclerview.widget.RecyclerView$5.attachViewToParent(RecyclerView.java:917)
	at androidx.recyclerview.widget.ChildHelper.attachViewToParent(ChildHelper.java:239)
	at androidx.recyclerview.widget.RecyclerView.addAnimatingView(RecyclerView.java:1438)
	at androidx.recyclerview.widget.RecyclerView.animateDisappearance(RecyclerView.java:4377)
	at androidx.recyclerview.widget.RecyclerView$4.processDisappeared(RecyclerView.java:616)
	at androidx.recyclerview.widget.ViewInfoStore.process(ViewInfoStore.java:242)
	at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep3(RecyclerView.java:4210)
	at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3864)
	at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4410)
	at android.view.View.layout(View.java:22213)
	at android.view.ViewGroup.layout(ViewGroup.java:6340)
	at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1131)
	at android.view.View.layout(View.java:22213)
	at android.view.ViewGroup.layout(ViewGroup.java:6340)
	at androidx.viewpager.widget.ViewPager.onLayout(ViewPager.java:1775)
	at android.view.View.layout(View.java:22213)
	at android.view.ViewGroup.layout(ViewGroup.java:6340)
	at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1829)
	at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1673)
	at android.widget.LinearLayout.onLayout(LinearLayout.java:1582)
	at android.view.View.layout(View.java:22213)
	at android.view.ViewGroup.layout(ViewGroup.java:6340)
	at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1131)
	at android.view.View.layout(View.java:22213)
	at android.view.ViewGroup.layout(ViewGroup.java:6340)
	at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
	at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
	at android.view.View.layout(View.java:22213)
	at android.view.ViewGroup.layout(ViewGroup.java:6340)
	at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1829)
	at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1673)
	at android.widget.LinearLayout.onLayout(LinearLayout.java:1582)
	at android.view.View.layout(View.java:22213)
	at android.view.ViewGroup.layout(ViewGroup.java:6340)
	at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
	at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
	at android.view.View.layout(View.java:22213)
	at android.view.ViewGroup.layout(ViewGroup.java:6340)
	at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1829)
	at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1673)
	at android.widget.LinearLayout.onLayout(LinearLayout.java:1582)
	at android.view.View.layout(View.java:22213)
	at android.view.ViewGroup.layout(ViewGroup.java:6340)
	at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
	at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
	at com.android.internal.policy.DecorView.onLayout(DecorView.java:905)
	at android.view.View.layout(View.java:22213)
	at android.view.ViewGroup.layout(ViewGroup.java:6340)
	at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:3286)
	at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2757)
	at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1865)
	at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7933)
	at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1018)
	at android.view.Choreographer.doCallbacks(Choreographer.java:837)
	at android.view.Choreographer.doFrame(Choreographer.java:767)
	at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1003)
	at android.os.Handler.handleCallback(Handler.java:883)
	at android.os.Handler.dispatchMessage(Handler.java:100)
	at android.os.Looper.loop(Looper.java:230)
	at android.app.ActivityThread.main(ActivityThread.java:7951)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:526)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1034)

问题分析

对同一个 position 位置同时进行notifyItemRemoved(position) 和 notifyItemInserted(position) 操作导致。

解决方案

避免同时对同一个位置先 notifyItemRemoved 再 notifyItemInserted，使用 notifyItemChanged。

adapter?.notifyItemChanged(position)

0x02 RecyclerView设置最大高度、宽度

当RecyclerView属性设置为wrap_content+maxHeight时，maxHeight没有效果。

问题分析

当RecyclerView的LayoutManager#isAutoMeasureEnabled()返回true时，RecyclerView高度取决于children view的布局高度，并非取决于RecyclerView自身的测量高度。

解决方案

因此，我们只需要重写LayoutManager的public void setMeasuredDimension(Rect childrenBounds, int wSpec, int hSpec)方法即可为RecyclerView设置最大宽高。

recyclerView.layoutManager = object : LinearLayoutManager(context, RecyclerView.VERTICAL, false) {
    override fun setMeasuredDimension(childrenBounds: Rect?, wSpec: Int, hSpec: Int) {
        val height = View.MeasureSpec.getSize(hSpec)
        val maxHeight = getScreenHeight() * 4 / 5
        val realHeight = height.coerceAtMost(maxHeight)
        val realHeightSpec = View.MeasureSpec.makeMeasureSpec(realHeight, AT_MOST)
        super.setMeasuredDimension(childrenBounds, wSpec, realHeightSpec)
    }
}

作者：猫爸iYao
链接：https://www.jianshu.com/p/0dec79ff70df
来源：简书
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