Recyclerview 移除最后一个item的 divider

在android开发中，有时候需要list进行页面的展示，可以使用listview，也可以使用recyclerview，当必须要使用recyclerview的时候（比如滑动删除，手势移动等），想要移除最后一个cell的divider，该怎么做？

上网查询，网上贴出来的源码（DividerItemDecoration.java）

public class DividerItemDecoration extends ItemDecoration {

..........

    public void onDraw(Canvas c, RecyclerView parent) {
        if(this.mOrientation == 1) {
            this.drawVertical(c, parent);
        } else {
            this.drawHorizontal(c, parent);
        }

    }

    public void drawVertical(Canvas c, RecyclerView parent) {
        int left = parent.getPaddingLeft();
        int right = parent.getWidth() - parent.getPaddingRight();
        int childCount = parent.getChildCount();

        for(int i = 0; i < childCount; ++i) {// ------> 这是重点
            View child = parent.getChildAt(i);
            LayoutParams params = (LayoutParams)child.getLayoutParams();
            int top = child.getBottom() + params.bottomMargin;
            int bottom = top + this.mDivider.getIntrinsicHeight();
            this.mDivider.setBounds(left, top, right, bottom);
            this.mDivider.draw(c);
        }

    }

    public void drawHorizontal(Canvas c, RecyclerView parent) {
        int top = parent.getPaddingTop();
        int bottom = parent.getHeight() - parent.getPaddingBottom();
        int childCount = parent.getChildCount();

        for(int i = 0; i < childCount; ++i) {// ------> 这是重点
            View child = parent.getChildAt(i);
            LayoutParams params = (LayoutParams)child.getLayoutParams();
            int left = child.getRight() + params.rightMargin;
            int right = left + this.mDivider.getIntrinsicHeight();
            this.mDivider.setBounds(left, top, right, bottom);
            this.mDivider.draw(c);
        }

    }

    public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
        if(this.mOrientation == 1) {
            outRect.set(0, 0, 0, this.mDivider.getIntrinsicHeight());
        } else {
            outRect.set(0, 0, this.mDivider.getIntrinsicWidth(), 0);
        }

    }
}

发现drawVertical和drawHorizontal是共有方法，于是想到可以自定义，然后重写这个方法，将 childCount 变成 childCount-1，这样就能解决。

然并卵，查看实际源码是这样的

public class DividerItemDecoration extends RecyclerView.ItemDecoration {
    public static final int HORIZONTAL = LinearLayout.HORIZONTAL;
    public static final int VERTICAL = LinearLayout.VERTICAL;

    private static final String TAG = "DividerItem";
    private static final int[] ATTRS = new int[]{ android.R.attr.listDivider };

    private Drawable mDivider;

    /**
     * Current orientation. Either {@link #HORIZONTAL} or {@link #VERTICAL}.
     */
    private int mOrientation;

    ..........

    private void drawVertical(Canvas canvas, RecyclerView parent) {
        canvas.save();
        final int left;
        final int right;
        //noinspection AndroidLintNewApi - NewApi lint fails to handle overrides.
        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; 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) {
        canvas.save();
        final int top;
        final int bottom;
        //noinspection AndroidLintNewApi - NewApi lint fails to handle overrides.
        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; i++) {
            final View child = parent.getChildAt(i);
            parent.getLayoutManager().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();
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent,
            RecyclerView.State state) {
        if (mDivider == null) {
            outRect.set(0, 0, 0, 0);
            return;
        }
        if (mOrientation == VERTICAL) {
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        }
    }
}

这两个方法并不能重写，但是呢，google还是很开明的，请注意 getItemOffsets()这个方法

重写这个方法即可

@Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        int position = parent.getChildAdapterPosition(view);
        // hide the divider for the last child
        if (position == parent.getAdapter().getItemCount() - 1) {
            outRect.setEmpty();
        } else {
            super.getItemOffsets(outRect, view, parent, state);
        }
    }