SimpleRecyclerViewDecoration for adding divider / custom drawable divider in RecyclerView

SimpleRecyclerViewDecoration.java

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;

public class SimpleRecyclerViewDecoration extends RecyclerView.ItemDecoration {
    private Drawable mDivider;
    private boolean mShowFirstDivider = false;
    private boolean mShowLastDivider = false;

    public SimpleRecyclerViewDecoration(Context context){
        final TypedArray a = context.obtainStyledAttributes(null, new int[]{android.R.attr.listDivider});
        mDivider = a.getDrawable(0);
        a.recycle();
    }

    public SimpleRecyclerViewDecoration(Context context, boolean showFirstDivider, boolean showLastDivider) {
        this(context);
        mShowFirstDivider = showFirstDivider;
        mShowLastDivider = showLastDivider;
    }

    public SimpleRecyclerViewDecoration(Drawable divider) {
        mDivider = divider;
    }

    public SimpleRecyclerViewDecoration(Drawable divider, boolean showFirstDivider, boolean showLastDivider) {
        this(divider);
        mShowFirstDivider = showFirstDivider;
        mShowLastDivider = showLastDivider;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {

        int currentItem = parent.getChildAdapterPosition(view);
        int totalItem = parent.getAdapter().getItemCount();
        int orientation = getOrientation(parent);

        if (orientation == LinearLayoutManager.VERTICAL) {
            int mDividerHeight = mDivider.getIntrinsicHeight();
            if(totalItem == 1){
                if(mShowFirstDivider) outRect.top = mDividerHeight;
                if(mShowLastDivider) outRect.bottom = mDividerHeight;
            }else if(currentItem == 0 && mShowFirstDivider){
                outRect.set(0, mDividerHeight, 0, mDividerHeight);
            }else if(currentItem == totalItem-1 && mShowLastDivider) {
                outRect.bottom = mDividerHeight;
            }else if(currentItem != totalItem-1 ){
                outRect.bottom = mDividerHeight;
            }

        } else {
            int mDividerWidth = mDivider.getIntrinsicWidth();
            if(totalItem == 1){
                if(mShowFirstDivider) outRect.left = mDividerWidth;
                if(mShowLastDivider) outRect.right = mDividerWidth;
            }else if(currentItem == 0 && mShowFirstDivider){
                outRect.set(mDividerWidth, 0, mDividerWidth, 0);
            }else if(currentItem == totalItem-1 && mShowLastDivider) {
                outRect.right = mDividerWidth;
            }else if(currentItem != totalItem-1 ){
                outRect.right = mDividerWidth;
            }
        }

    }

    @Override
    public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int orientation = getOrientation(parent);
        int childCount = parent.getChildCount();

        for (int i = 0; i < childCount; i++) {
            View child = parent.getChildAt(i);
            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();

            if(orientation == LinearLayoutManager.VERTICAL){
                if(childCount == 1){
                    if(mShowFirstDivider) drawVerticalLayoutDivider_Top(parent, child, c, params);
                    if(mShowLastDivider) drawVerticalLayoutDivider_Bottom(parent, child, c, params);
                }
                else if(i == 0 && mShowFirstDivider) {
                    drawVerticalLayoutDivider_Top(parent, child, c, params);
                    drawVerticalLayoutDivider_Bottom(parent, child, c, params);
                }
                else if(i == childCount-1 && mShowLastDivider) {
                    drawVerticalLayoutDivider_Bottom(parent, child, c, params);
                }
                else if(i != childCount-1){
                    drawVerticalLayoutDivider_Bottom(parent, child, c, params);
                }
            }else {
                if(childCount == 1){
                    if(mShowFirstDivider) drawHorizontalLayoutDivider_Left(parent, child, c, params);
                    if(mShowLastDivider) drawHorizontalLayoutDivider_Right(parent, child, c, params);
                }
                else if(i == 0 && mShowFirstDivider) {
                    drawHorizontalLayoutDivider_Left(parent, child, c, params);
                    drawHorizontalLayoutDivider_Right(parent, child, c, params);
                }
                else if(i == childCount-1 && mShowLastDivider) {
                    drawHorizontalLayoutDivider_Right(parent, child, c, params);
                }
                else if(i != childCount-1){
                    drawHorizontalLayoutDivider_Right(parent, child, c, params);
                }
            }
        }
    }

    private void drawVerticalLayoutDivider_Top(RecyclerView parent, View child, Canvas c, RecyclerView.LayoutParams params){
        int left = parent.getPaddingLeft();
        int right = parent.getWidth() - parent.getPaddingRight();
        int top = child.getTop() - params.topMargin - mDivider.getIntrinsicHeight();
        int bottom = top + mDivider.getIntrinsicHeight();
        mDivider.setBounds(left, top, right, bottom);
        mDivider.draw(c);
    }

    private void drawVerticalLayoutDivider_Bottom(RecyclerView parent, View child, Canvas c, RecyclerView.LayoutParams params){
        int left = parent.getPaddingLeft();
        int right = parent.getWidth() - parent.getPaddingRight();
        int top = child.getBottom() + params.topMargin;
        int bottom = top + mDivider.getIntrinsicHeight();
        mDivider.setBounds(left, top, right, bottom);
        mDivider.draw(c);
    }

    private void drawHorizontalLayoutDivider_Left(RecyclerView parent, View child, Canvas c, RecyclerView.LayoutParams params){
        int left = child.getLeft() - params.leftMargin - mDivider.getIntrinsicWidth();
        int right = left + mDivider.getIntrinsicWidth();
        int top = parent.getPaddingTop();
        int bottom = parent.getHeight() - parent.getPaddingBottom();
        mDivider.setBounds(left, top, right, bottom);
        mDivider.draw(c);
    }

    private void drawHorizontalLayoutDivider_Right(RecyclerView parent, View child, Canvas c, RecyclerView.LayoutParams params){
        int left = child.getRight() + params.rightMargin;
        int right = left + mDivider.getIntrinsicWidth();
        int top = parent.getPaddingTop();
        int bottom = parent.getHeight() - parent.getPaddingBottom();
        mDivider.setBounds(left, top, right, bottom);
        mDivider.draw(c);
    }

    private int getOrientation(RecyclerView parent) {
        if (parent.getLayoutManager() instanceof LinearLayoutManager) {
            LinearLayoutManager layoutManager = (LinearLayoutManager) parent.getLayoutManager();
            return layoutManager.getOrientation();
        } else {
            throw new IllegalStateException("SimpleRecyclerViewDecoration can only be used with a LinearLayoutManager.");
        }
    }

}

Readme.md

SimpleRecyclerViewDecoration

Simple RecyclerView ItemDecoration for divider

Features

• Define own drawable as divider
• Able to use android default divider if were not define
• Custom setting on divider to show before first item or last item
• Only works with LinearLayoutManager

Example

Default android divider

mRecyclerView.addItemDecoration(
  new SimpleRecyclerViewDecoration(context));

Default android divider with first item top divider or last item bottom divider

mRecyclerView.addItemDecoration(
  new SimpleRecyclerViewDecoration(context, true, true));

Custom divider with no first item top divider and last item bottom divider

mRecyclerView.addItemDecoration(
  new SimpleRecyclerViewDecoration(context.getDrawable(R.drawable.custom_drawable)));

Custom divider with first also end and last dividers

mRecyclerView.addItemDecoration(
  new SimpleRecyclerViewDecoration(context.getDrawable(R.drawable.custom_drawable), true, true));

custom_drawable.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <size
        android:width="2dp"
        android:height="2dp" />
    <solid android:color="#FF000000" />
</shape>