以编程方式添加时未显示 MaterialCardView

问题描述

以编程方式添加时，我无法在我的活动中看到 MaterialViewCard。如果我直接在 XML 上添加，它会显示。但是当通过 Kotling 添加时，它不会。

XML 示例：

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".SecondFragment">

    <LinearLayout
        android:id="@+id/layout_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent">
        <LinearLayout
            android:id="@+id/layout_first_block"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            android:layout_weight="1">
            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal">
                <com.google.android.material.card.MaterialCardView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    app:cardBackgroundColor="@color/surface"
                    android:layout_margin="2dp">
                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="00"
                        android:textColor="@color/on_surface"/>
                </com.google.android.material.card.MaterialCardView>
                <com.google.android.material.card.MaterialCardView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    app:cardBackgroundColor="@color/surface"
                    android:layout_margin="2dp">
                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="01"
                        android:textColor="@color/on_surface"/>
                </com.google.android.material.card.MaterialCardView>
                <com.google.android.material.card.MaterialCardView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    app:cardBackgroundColor="@color/surface"
                    android:layout_margin="2dp">
                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="03"
                        android:textColor="@color/on_surface"/>
                </com.google.android.material.card.MaterialCardView>
            </LinearLayout>
        </LinearLayout>
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            android:gravity="center"
            android:layout_weight="1">
            <Button
                android:id="@+id/button_second"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/previous"/>
        </LinearLayout>
    </LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

结果： Cards added via XML

但是当我尝试这个（如下）时将不起作用。 XML：

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".SecondFragment">

    <LinearLayout
        android:id="@+id/layout_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent">
        <LinearLayout
            android:id="@+id/layout_first_block"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            android:layout_weight="1">
<!--            Will add here-->
        </LinearLayout>
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            android:gravity="center"
            android:layout_weight="1">
            <Button
                android:id="@+id/button_second"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/previous"/>
        </LinearLayout>
    </LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

科特林：

override fun onViewCreated(view: View,savedInstanceState: Bundle?) {
        super.onViewCreated(view,savedInstanceState)

        view.findViewById<Button>(R.id.button_second).setOnClickListener {
            findNavController().navigate(R.id.action_SecondFragment_to_FirstFragment)
        }

        val layoutFirstBlock: LinearLayout = view.findViewById<LinearLayout>(R.id.layout_first_block)

        for (r in 1..10){
            val row: LinearLayout = LinearLayout(context)
            row.orientation = LinearLayout.HORIZONTAL
            row.layoutParams = LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,LinearLayout.LayoutParams.WRAP_CONTENT)

            for(c in 1..10){
                val card: MaterialCardView = MaterialCardView(context)
                val marginParams: ViewGroup.MarginLayoutParams = ViewGroup.MarginLayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,ViewGroup.LayoutParams.WRAP_CONTENT)
                marginParams.setMargins(R.dimen.small_padding,R.dimen.small_padding,R.dimen.small_padding)
                card.layoutParams = marginParams
                card.setBackgroundColor(resources.getColor(R.color.surface,context?.theme))

                val num: TextView = TextView(context)
                num.layoutParams = ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,ViewGroup.LayoutParams.WRAP_CONTENT)
                val value = ((r-1)*10 + c).toString()
                num.text = value
                num.setTextColor(resources.getColor(R.color.on_surface,context?.theme))

                Log.d("i","i$r$c = $value")

                card.addView(num)
                row.addView(card)
            }
            layoutFirstBlock.addView(row,0)
        }
    }

结果：Cards missing when added by Kotlin

有什么想法吗？

谢谢！

解决方法

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kotlin kotlin materialcardview programmatically-created