优化RecyclerView item间距 实现按文本长度动态调整列数方案求助

你需要的是自动换行的流式标签布局，Android官方提供的FlexboxLayoutManager可以直接满足动态列数的需求，不需要手动计算列宽和排列逻辑，具体实现步骤如下：

1. 引入Flexbox依赖 #

在模块级build.gradle文件中添加依赖：

dependencies {
    implementation 'com.google.android.flexbox:flexbox:3.0.0'
}

2. 替换RecyclerView的布局管理器 #

把原来的GridLayoutManager替换为FlexboxLayoutManager，同时做RTL适配和排列配置：

val arr:ArrayList<String> = arrayListOf("English","Intermediate","English","English","arr","UICollectionViewFlowLayoutFlowFlowFlow","English","UICollectionViewDelegate","English","Intermediate","UIViewController","viewDidLoad","Intermediate","String","Intermediate","arr","Intermediate","UIKit","Intermediate","English","columnLayout","English","languageLabel")

// 配置Flexbox布局管理器
val flexboxManager = FlexboxLayoutManager(this).apply {
    // 主轴为横向
    flexDirection = FlexDirection.ROW
    // 超过宽度自动换行
    flexWrap = FlexWrap.WRAP
    // 适配RTL布局，内容从右往左排列
    layoutDirection = View.LAYOUT_DIRECTION_RTL
    // 主轴对齐方式
    justifyContent = JustifyContent.FLEX_START
    // 次轴对齐方式
    alignItems = AlignItems.CENTER
}
recyclerView.layoutManager = flexboxManager
// 添加item间距装饰器
recyclerView.addItemDecoration(TagItemDecoration(10.dpToPx()))
adaAdapter = CustomAdapter(this, arr)
recyclerView.adapter = adaAdapter

注：上面用到的dpToPx()是dp转像素的通用扩展方法，用来适配不同设备的屏幕密度，你也可以直接传入像素值。

3. 修改Item布局，移除固定宽度 #

把Item布局里的固定宽高配置替换为自适应，删除多余嵌套层级：

<?xml version="1.0" encoding="utf-8"?> 
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/mainL"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:padding="10dp">

        <TextView
            android:id="@+id/typeTv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="TextView"
            android:textSize="14sp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

4. 删除Adapter里的固定宽度逻辑 #

Adapter不需要再手动计算Item宽度，简化后代码如下：

class CustomAdapter(val context: DreamsActivity, val items: ArrayList<String>) : RecyclerView.Adapter<CustomAdapter.ViewHolderProductList>() {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolderProductList {
        val layoutInflater = LayoutInflater.from(parent.context)
        val cellForRow = layoutInflater.inflate(R.layout.dreams_collection,parent, false)
        return ViewHolderProductList(cellForRow)
    }

    override fun getItemCount(): Int = items.size

    override fun onBindViewHolder(holder: ViewHolderProductList, position: Int) {
        holder.typeTv.text = items[position]
    }

    inner class ViewHolderProductList(itemView: View) : RecyclerView.ViewHolder(itemView) {
        var typeTv: TextView =  itemView.findViewById(R.id.typeTv)
        var mainL: ConstraintLayout =  itemView.findViewById(R.id.mainL)
    }
}

5. 实现ItemDecoration统一控制间距 #

自定义装饰器来统一设置Item之间的上下左右间距，适配设计稿要求：

class TagItemDecoration(private val space: Int) : RecyclerView.ItemDecoration() {
    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
        outRect.top = space
        outRect.bottom = space
        outRect.left = space
        outRect.right = space
    }
}

如果需要调整间距，直接修改构造参数里的数值即可。

内容的提问来源于stack exchange，提问作者sheko