Extension of androidx.recyclerview.widget.DividerItemDecoration that removes the divider after the last item

DividerItemDecoration.java

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.view.View;

import androidx.recyclerview.widget.RecyclerView;

/**
 * Extension of androidx.recyclerview.widget.DividerItemDecoration that removes the divider after the last item
 * 
 * DividerItemDecoration is a {@link RecyclerView.ItemDecoration} that can be used as a divider
 * between items of a {@link androidx.recyclerview.widget.LinearLayoutManager}. It supports both {@link #HORIZONTAL} and
 * {@link #VERTICAL} orientations.
 *
 * <pre>
 *     mDividerItemDecoration = new DividerItemDecoration(recyclerView.getContext(),
 *             mLayoutManager.getOrientation());
 *     recyclerView.addItemDecoration(mDividerItemDecoration);
 * </pre>
 */
public class DividerItemDecoration extends androidx.recyclerview.widget.DividerItemDecoration {

    // Workaround: Duplicated properties as they are private in parent
    private int mOrientation;
    private final Rect mBounds = new Rect();

    public DividerItemDecoration(Context context, int orientation) {
        super(context, orientation);
    }

    @Override
    public void setOrientation(int orientation) {
        super.setOrientation(orientation);
        this.mOrientation = orientation;
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        if (parent.getLayoutManager() == null || getDrawable() == null) {
            return;
        }
        if (mOrientation == VERTICAL) {
            drawVertical(c, parent);
        } else {
            drawHorizontal(c, parent);
        }
    }

    private void drawVertical(Canvas canvas, RecyclerView parent) {
        Drawable mDivider = getDrawable();
        if (mDivider == null) {
            return;
        }

        canvas.save();
        final int left;
        final int right;
        if (parent.getClipToPadding()) {
            left = parent.getPaddingLeft();
            right = parent.getWidth() - parent.getPaddingRight();
            canvas.clipRect(left, parent.getPaddingTop(), right,
                    parent.getHeight() - parent.getPaddingBottom());
        } else {
            left = 0;
            right = parent.getWidth();
        }

        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount - 1; i++) {
            final View child = parent.getChildAt(i);
            parent.getDecoratedBoundsWithMargins(child, mBounds);
            final int bottom = mBounds.bottom + Math.round(child.getTranslationY());
            final int top = bottom - mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(canvas);
        }
        canvas.restore();
    }

    private void drawHorizontal(Canvas canvas, RecyclerView parent) {
        Drawable mDivider = getDrawable();
        if (mDivider == null) {
            return;
        }

        canvas.save();
        final int top;
        final int bottom;
        if (parent.getClipToPadding()) {
            top = parent.getPaddingTop();
            bottom = parent.getHeight() - parent.getPaddingBottom();
            canvas.clipRect(parent.getPaddingLeft(), top,
                    parent.getWidth() - parent.getPaddingRight(), bottom);
        } else {
            top = 0;
            bottom = parent.getHeight();
        }

        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount - 1; i++) {
            final View child = parent.getChildAt(i);
            RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
            if (layoutManager != null) {
                layoutManager.getDecoratedBoundsWithMargins(child, mBounds);
                final int right = mBounds.right + Math.round(child.getTranslationX());
                final int left = right - mDivider.getIntrinsicWidth();
                mDivider.setBounds(left, top, right, bottom);
                mDivider.draw(canvas);
            }
        }
        canvas.restore();
    }
}