RecyclerView中最后一个孩子的边距/填充

我正在尝试在最后一行添加填充/边距底部，在第一行添加填充/边距顶部。我无法在xml项目中执行此操作，因为它会影响我所有的孩子。

我的RecyclerView适配器中有标题和子元素，因此我不能使用

   android:padding="4dp"
   android:clipToPadding="false"

我需要在每个标题的最后第一行中单独使用它

我在科特林用这个

override fun onBindViewHolder(holder: RecyclerView.ViewHolder(view), position: Int) {
    if (position == itemsList.lastIndex){
        val params = holder.itemView.layoutParams as FrameLayout.LayoutParams
        params.bottomMargin = 100
        holder.itemView.layoutParams = params
    }else{
        val params = holder.itemView.layoutParams as RecyclerView.LayoutParams
        params.bottomMargin = 0
        holder.itemView.layoutParams = params
    }
  //other codes ...
}

这个问题甚至更容易解决。您可以对RecylerView自身应用必要的填充并将其设置clipToPadding为false，否则填充将切断滚动区域。这是一个例子

<android.support.v7.widget.RecyclerView
    android:padding="4dp"
    android:clipToPadding="false"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

看到填充将在所有侧面（包括顶部和底部）添加4dp。然后，clipToPadding参数确保您的子项没有被切掉。现在，4dp为您的子项目的所有侧面添加填充，您就可以开始了。总共可以在侧面和物品之间获得8dp填充。

您可以仅将RepaderView的顶部和底部添加填充并将clipToPadding属性设置为，而不必在顶部和底部都添加填充false。

<android.support.v7.widget.RecyclerView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:clipToPadding="false"
    android:paddingTop="8dp"
    android:paddingBottom="8dp" />

用途ItemDecoration：

private class SpacesItemDecoration extends RecyclerView.ItemDecoration {
    private int space;

    public SpacesItemDecoration(int space) {
        this.space = space;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        int position = parent.getChildAdapterPosition(view);
        boolean isLast = position == state.getItemCount()-1;
        if(isLast){
            outRect.bottom = space;
            outRect.top = 0; //don't forget about recycling...
        }
        if(position == 0){
            outRect.top = space;
            // don't recycle bottom if first item is also last
            // should keep bottom padding set above
            if(!isLast)
                outRect.bottom = 0;
        }
    }
}

和

//8dp as px
int space = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 8,
            getResources().getDisplayMetrics()); // calculated
//int space = getResources().getDimensionPixelSize(
//    R.dimen.list_item_padding_vertical); // from resources
recyclerView.addItemDecoration(new SpacesItemDecoration(space));

<android.support.v7.widget.RecyclerView
    android:id="@+id/rv_tpf"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:clipToPadding="false"
    android:paddingBottom="100dp" />

在您的recyclerview中添加android:clipToPadding="false"和android:paddingBottom="100dp"。

在您的recyclerview中添加android：clipToPadding =“ false”和android：paddingBottom =“ 65dp”。如果您使用的是fab菜单按钮和对回收者视图单元的操作。

<androidx.recyclerview.widget.RecyclerView
      android:id="@+id/dinner_recycler_view"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:clipToPadding="false"
      android:paddingBottom="65dp"/>

由于某种原因，旧的clipToPadding=false解决方案对我不起作用。所以我添加了一个ItemDecoration

https://gist.github.com/kassim/582888fa5960791264fc92bc41fb6bcf

public class BottomPaddingDecoration extends RecyclerView.ItemDecoration {
    private final int bottomPadding;

    public BottomPaddingDecoration(int bottomPadding) {
        this.bottomPadding = bottomPadding;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        int position = ((RecyclerView.LayoutParams) view.getLayoutParams()).getViewLayoutPosition();
        if (position == parent.getAdapter().getItemCount() - 1) {
            outRect.set(0, 0, 0, bottomPadding);
        }
    }
}

我已经修改了惊人的答案@snachmsm答案，以便更好，让您知道如何正确使用

public class SpacesItemDecoration extends DividerItemDecoration {
    private int space;

    public SpacesItemDecoration(Context clContext,int oriantation,int space) {
        super(clContext,oriantation);
        this.space = space;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        super.getItemOffsets(outRect,view,parent,state);
        int position = parent.getChildAdapterPosition(view);
        boolean isLast = position == state.getItemCount()-1;
        if(isLast){
            outRect.bottom = space;
            outRect.top = 0; //don't forget about recycling...
        }
       /* if(position == 0){
            outRect.top = space;
            // don't recycle bottom if first item is also last
            // should keep bottom padding set above
            if(!isLast)
                outRect.bottom = 0;
        }*/
    }
}