我在我的项目文件的XML设置视图（卡片视图）的保证金，这个XML文件的项目将使用在我recyclerView适配器。
正如你可以在下面我的XML看，我已经给保证金顶部，底部，开始和结束。我想保证金从我的片段改变
这里是我的xml文件，item_category_list.xml：
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView
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="wrap_content"
app:cardCornerRadius="8dp"
app:cardElevation="4dp"
android:id="@+id/cardView_item_category_list" android:layout_marginStart="8dp" android:layout_marginEnd="8dp"
android:layout_marginBottom="8dp" android:layout_marginTop="8dp">
<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="wrap_content"
android:background="@android:color/background_light">
<ImageView
android:layout_width="0dp"
android:layout_height="0dp"
app:srcCompat="@drawable/logo_apps"
android:id="@+id/categoryImageView_Item"
android:layout_marginTop="16dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"
android:layout_marginStart="24dp"
app:layout_constraintEnd_toEndOf="parent"
android:layout_marginEnd="24dp"
app:layout_constraintDimensionRatio="w,1:1" android:scaleType="centerCrop"/>
<TextView
android:text="@string/Category"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/categoryName_textView_item"
app:layout_constraintTop_toBottomOf="@+id/categoryImageView_Item"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
android:layout_marginStart="4dp"
app:layout_constraintEnd_toEndOf="parent"
android:layout_marginEnd="4dp"
android:textAlignment="center"
android:minLines="1"
android:maxLines="2"
app:autoSizeTextType="uniform"
app:autoSizeMinTextSize="10sp"
app:autoSizeMaxTextSize="15sp"
app:autoSizeStepGranularity="1sp"
android:layout_marginBottom="24dp"
android:layout_marginTop="24dp"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>
这里是适配器：
class CategoryAdapter(val context: Context, val categories: List<Category>) : RecyclerView.Adapter<CategoryAdapter.ViewHolderCategory>() {
private lateinit var mListener : CategoryAdapterListener
interface CategoryAdapterListener {
fun onItemClick(position: Int)
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolderCategory {
val layoutInflater = LayoutInflater.from(parent.context)
val itemView = layoutInflater.inflate(R.layout.item_category_list,parent, false)
return ViewHolderCategory(itemView,mListener)
}
override fun getItemCount(): Int {
return categories.size
}
override fun onBindViewHolder(holder: ViewHolderCategory, position: Int) {
val category = categories[position]
holder.categoryNameTextView.text = category.name
Glide
.with(context)
.load(category.getFormattedImageURL())
.into(holder.categoryImageView)
}
inner class ViewHolderCategory(itemView: View, listener: CategoryAdapterListener) : RecyclerView.ViewHolder(itemView) {
val categoryImageView = itemView.findViewById<ImageView>(R.id.categoryImageView_Item)
val categoryNameTextView = itemView.findViewById<TextView>(R.id.categoryName_textView_item)
val cardView = itemView.findViewById<CardView>(R.id.cardView_item_category_list)
init {
itemView.setOnClickListener {
val position = adapterPosition
if (position != RecyclerView.NO_POSITION) {
listener.onItemClick(position)
}
}
}
}
fun setCategoryAdapterListener(listener: CategoryAdapterListener) {
mListener = listener
}
}
而在片段，我适配器设置为回收站观点：
val categoryAdapter = CategoryAdapter(mContext,parentCategory)
val layoutManager = GridLayoutManager(mContext,4,RecyclerView.VERTICAL,false)
recyclerViewParentCategory.adapter = categoryAdapter
recyclerViewParentCategory.layoutManager = layoutManager
recyclerViewParentCategory.setHasFixedSize(true)
我想通过编程修改卡认为，利润率在我item_category_list.xml在我的Java /科特林文件（在我的片段文件），这样我就可以将利润率从我的片段而改变。
那么，如何实现呢？的Java /科特林任何语言者优先。
首先，它是一个很长的路要走。所以我只是建议的方式。
interface ChangeMargin）。在片段创建界面并实现在适配器中像这样的接口class CategoryAdapter(val context: Context, val categories: List<Category>):RecyclerView.Adapter<CategoryAdapter.ViewHolderCategory>(),ChangeMargin()
对于如何创建接口，以便可以顺利通过this
@Override
public void ChangeMargin() {
val linear_params=LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,LinearLayout.LayoutParams.WRAP_CONTENT)
linear_params.setMargins(leftMargin,topmargin,rightMargin,bottomMargin)
cardView?.layoutParams=linear_params
}
不要忘记通知适配器
你可以做这样的事情。让cardview的ID，在适配器中创建它的实例，并做到这一点代码
ViewGroup.MarginLayoutParams的LayoutParams =（ViewGroup.MarginLayoutParams）myCardView.getLayoutParams（）; layoutParams.setMargins（10，10，10，10）;
myCardView.requestLayout();
要设置页边距为cardView，你必须创建layoutParams，设置页边距，然后将其设置为cardView的LayoutParams这样的：
inner class ViewHolderCategory(itemView: View, listener: CategoryAdapterListener) : RecyclerView.ViewHolder(itemView) {
val categoryImageView = itemView.findViewById<ImageView>(R.id.categoryImageView_Item)
val categoryNameTextView = itemView.findViewById<TextView>(R.id.categoryName_textView_item)
val cardView = itemView.findViewById<CardView>(R.id.cardView_item_category_list)
//Main code here
val lparams=LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,LinearLayout.LayoutParams.WRAP_CONTENT)
lparams.setMargins(leftMargin,topmargin,rightMargin,bottomMargin)
cardView?.layoutParams=lparams
}