前言

在平常的開發(fā)中應(yīng)該都遇到過在給RecyclerView加一個(gè)高度上限, 但是在當(dāng)前版本的lib中是不支持這個(gè)操作的哦.. 手動(dòng)動(dòng)態(tài)設(shè)定也不是很直觀, 用同級(jí)別view擠壓的方式可以實(shí)現(xiàn)效果,但是已經(jīng)背離了初衷, 將代碼放在下方, 目前我用著沒問題, 如果是v7包的把a(bǔ)ndroidx換成v7包即可. 體量比較小沒用上傳github ... 轉(zhuǎn)載請(qǐng)注明

未使用MaxHeight

未使用MaxHeight情況

需求

使用之后

import android.content.Context
import android.util.AttributeSet
import androidx.recyclerview.widget.RecyclerView
import kotlin.math.min

/**
* email: ningning21_h@foxmail.com
*/
class MaxHeightRecyclerView : RecyclerView {

    private var maxHeight: Int = -1

    constructor(context: Context) : this(context, null)

    constructor(context: Context, attrs: AttributeSet?) : this(context, attrs, 0)

    constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(context, attrs, defStyleAttr) {
        attrs?.let { attrSet ->
            val attrRes = intArrayOf(android.R.attr.maxHeight)
            val types = context.obtainStyledAttributes(attrSet, attrRes)
            maxHeight = types.getDimensionPixelSize(0, -1)
            types.recycle()
        }
    }

    override fun onMeasure(widthSpec: Int, heightSpec: Int) {
        val hSize = MeasureSpec.getSize(heightSpec)
        val heightMeasureSpec = if (maxHeight < 0) {
            heightSpec
        } else {
            when (MeasureSpec.getMode(heightSpec)) {
                MeasureSpec.AT_MOST -> MeasureSpec.makeMeasureSpec(min(hSize, maxHeight), MeasureSpec.AT_MOST)
                MeasureSpec.UNSPECIFIED -> MeasureSpec.makeMeasureSpec(maxHeight, MeasureSpec.AT_MOST)
                MeasureSpec.EXACTLY -> MeasureSpec.makeMeasureSpec(min(hSize, maxHeight), MeasureSpec.EXACTLY)
                else -> MeasureSpec.makeMeasureSpec(maxHeight, MeasureSpec.AT_MOST)
            }
        }
        super.onMeasure(widthSpec, heightMeasureSpec)
    }
}

用法

代碼中android:layout_height屬性最好用wrap_content , 在constraintlayout中盡量不要上下依賴然后高度設(shè)定為0dp這種用法, 適用于各種LayoutManager , java項(xiàng)目一樣適用, 添加kt支持庫(kù)之后就行了, 或者翻譯成java吧

注: android:maxHeight只能在constraintlayout中使用

            <MaxHeightRecyclerView
                android:id="@+id/recyclerView"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:maxHeight="@dimen/comm_dp_84"
                android:layout_marginBottom="@dimen/dp_4"
                android:scrollbars="vertical"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintTop_toBottomOf="@id/tag"
                app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
                tools:listitem="@layout/item">
            </MaxHeightRecyclerView>