如何在 Kotlin 的卡片视图中设置属性

Question

我正在设计一个 Feed，其中我希望以卡片的形式发布帖子，我使用 Google 的设计库实现了卡片。我已经创建了我的布局，但由于帖子将被动态获取，因此我想在 Kotlin 中动态创建我的布局。为此，我创建了一个函数，它将 Image、Title、Description 作为参数并返回一个 Card View 对象。

为了在 CardView 中设置属性，我尝试了 layoutParams，但使用它只会让我的应用崩溃

 val cardViewParam = cardView.layoutParams as CoordinatorLayout.LayoutParams

在这段代码中，我尝试了每种布局类型 Linear、Relative、Coordinator 甚至 ViewGroup，但我的应用每次都会崩溃。

这是我的布局：

<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:tools="http://schemas.android.com/tools"
            xmlns:app="http://schemas.android.com/apk/res-auto"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            tools:context=".Home"
            android:background="@color/DirtyWhite"
            android:scrollbars="none">
    <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            android:tag="FEED">

//This is the card view which I want to create dynamically

        <android.support.v7.widget.CardView android:layout_width="match_parent"
                                            android:layout_height="wrap_content"
                                            android:layout_margin="5dp"
                                            android:elevation="50dp"
                                            app:cardCornerRadius="10dp">

            <LinearLayout android:layout_width="match_parent"
                          android:layout_height="wrap_content"
                          android:orientation="vertical"
                          android:padding="10dp"
                          android:clipToPadding="false">

                <ImageView android:layout_width="match_parent"
                           android:layout_height="180dp"
                           android:src="@drawable/sample"
                           android:scaleType="centerCrop"
                           android:layout_marginTop="-10dp"
                           android:layout_marginStart="-10dp"
                           android:layout_marginEnd="-10dp"
                           android:layout_marginBottom="-10dp"
                           android:adjustViewBounds="true"/>
                <TextView
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        style="@style/Base.TextAppearance.AppCompat.Title"
                        android:text="This is a  part of Material Design."
                        android:ellipsize="end"
                        android:maxLines="1"
                        android:layout_marginTop="16dp"
                />
                <TextView
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        style="@style/TextAppearance.AppCompat.Body2"
                        android:text="This is a  part of Material Design. This is a  part of Material Design. This is a  part of Material Design. "
                        android:ellipsize="end"
                        android:textColor="@color/realGray"
                        android:maxLines="2"
                        android:layout_marginTop="8dp"
                />

                <RelativeLayout android:layout_width="match_parent"
                                android:layout_marginTop="8dp"
                                android:layout_height="wrap_content">
                    <RatingBar android:layout_width="wrap_content" android:layout_height="wrap_content"
                               android:numStars="5"
                               android:rating="3"
                               android:isIndicator="true"
                               android:layout_alignParentLeft="true"
                               android:layout_alignParentStart="true"
                               android:layout_centerInParent="true"
                               style="@style/Base.Widget.AppCompat.RatingBar.Small"/>
                    <LinearLayout android:layout_width="wrap_content" android:layout_height="wrap_content"
                                  android:layout_alignParentRight="true"
                                  android:layout_alignParentEnd="true">
                        <Button android:layout_width="wrap_content" android:layout_height="wrap_content"
                                android:background="@drawable/ic_favorite_border_black_24dp"
                                android:minHeight="30dp"
                                android:minWidth="30dp"
                                android:layout_marginRight="15dp"
                                android:layout_marginEnd="15dp"
                        />
                        <Button android:layout_width="wrap_content"
                                android:layout_height="wrap_content"
                                android:text="Order Now"
                                android:background="@drawable/rounded_card_button_small"
                                android:textColor="@color/DirtyWhite"
                                android:minHeight="0dp"
                                android:minWidth="0dp"
                                android:padding="5dp"/>
                    </LinearLayout>


                </RelativeLayout>

            </LinearLayout>

        </android.support.v7.widget.CardView>


    </LinearLayout>
</ScrollView>

我尝试了这段代码来动态创建布局： （注意：此代码仅用于创建基本卡片，不包括评分栏和其他操作按钮）

fun createAdsPost(view: View, photo: ImageView, titleText: String, descText: String): CardView {

    val cardView = CardView(view.context)
    val cardViewParam = cardView.layoutParams as CoordinatorLayout.LayoutParams
    cardView.layoutParams = cardViewParam
    cardViewParam.width = LinearLayout.LayoutParams.MATCH_PARENT
    cardViewParam.height = LinearLayout.LayoutParams.WRAP_CONTENT
    cardViewParam.setMargins(dpToPx(5, view), dpToPx(5, view), dpToPx(5, view), dpToPx(5, view))
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        cardView.elevation = dpToPx(50, view).toFloat()
    }
    cardView.apply {
    radius = dpToPx(10, view).toFloat()
        this.layoutParams = cardViewParam

    }
    val linear1 = LinearLayout(view.context)
     linear1.orientation = LinearLayout.VERTICAL
     linear1.setPadding(dpToPx(10, view), dpToPx(10, view), dpToPx(10, view), dpToPx(10, view))
     linear1.clipToPadding = false
     val linear1Param = linear1.layoutParams as LinearLayout.LayoutParams
     linear1Param.width = LinearLayout.LayoutParams.MATCH_PARENT
     linear1Param.height = LinearLayout.LayoutParams.WRAP_CONTENT
     linear1.layoutParams = linear1Param
     photo.scaleType = ImageView.ScaleType.CENTER_CROP
     photo.adjustViewBounds = true
     val photoParams = photo.layoutParams as LinearLayout.LayoutParams
     photoParams.apply {
         width = LinearLayout.LayoutParams.MATCH_PARENT
         height = dpToPx(180, view)
         topMargin = dpToPx(-10, view)
         bottomMargin = dpToPx(-10, view)
     }
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
         photoParams.marginStart = dpToPx(-10, view)
         photoParams.marginEnd = dpToPx(-10, view)
     }
     linear1.addView(photo)
      val title = TextView(view.context) 
       title.apply {
           ellipsize = TextUtils.TruncateAt.END
           maxLines = 1
           text = titleText
       }
       val titleTextParams = title.layoutParams as LinearLayout.LayoutParams
       titleTextParams.apply {
           width = LinearLayout.LayoutParams.MATCH_PARENT
           height = LinearLayout.LayoutParams.WRAP_CONTENT
           topMargin = dpToPx(16, view)
       }
      linear1.addView(title)
     val desc = TextView(view.context)
      desc.apply {
          ellipsize = TextUtils.TruncateAt.END
          maxLines = 2
          text = descText
          setTextColor(Color.parseColor("#626567"))
      }
      val descTextParams = desc.layoutParams as LinearLayout.LayoutParams
      descTextParams.apply {
          width = LinearLayout.LayoutParams.MATCH_PARENT
          height = LinearLayout.LayoutParams.WRAP_CONTENT
          topMargin = dpToPx(8, view)

      }
     linear1.addView(desc)
    cardView.addView(linear1)

    return cardView
}

当我使用这些代码时，我的应用程序崩溃了。我尝试调试我的代码，发现第一个错误出现在 CardView 的layoutParams 中。 总之，我想知道如何在卡片视图中设置属性 另外，请告诉这是创建动态布局的唯一方法还是有更有效的方法。我是 Android 开发新手。

Answer 1

我想建议一件事，如果您的要求是动态创建视图，那么您只需尝试一件事：

1) 为您的动态视图制作一个单独的布局文件 2) 使用以下方法扩展该布局：

val layoutInflater = getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater
    layoutInflater!!.inflate(R.layout.your_layout_file)

3) 现在您将拥有视图，然后您只需要使用以下方式访问布局视图：

view.findViewById(you view id)

4) 现在您将能够轻松地动态创建和访问您的视图

Note:

getContent() : will come according to your usage on fragment or in activity, so need to change it accordingly
same as inflate method, use parameter according to your requirement

Answer 2

您将LayoutParams 转换为CoordinatorLayout.LayoutParams，而您正在动态创建一个没有父视图的视图，我认为这就是问题所在。

如果您是动态创建视图，那么您也应该根据其父容器创建新的LayoutParams。

例如，如果您想在LinearLayout 中添加CardView，则LayoutParams 应如下所示：

val cardView = CardView(view.context)
val cardViewParams = LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT).also {
  it.setMargins(dpToPx(5, view), dpToPx(5, view), dpToPx(5, view), dpToPx(5, view))
}

cardView.apply {
        radius = dpToPx(10, view).toFloat()
            this.layoutParams = cardViewParam

        }
...
...

val linear1 = LinearLayout(view.context)
val linear1Param = FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.WRAP_CONTENT)
...
...
cardView.addView(linear1)

对于linear1，我们采用FrameLayout.LayoutParams，因为在我们的例子中，我们将把它添加为CardView 的子代，CardView 是扩展的FrameLayout。