An ItemDecoration that would draw a line between every RecyclerView items.

DividerItemDecoration.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.util.AttributeSet;
import android.view.View;

public class DividerItemDecoration extends RecyclerView.ItemDecoration {
 
   private static final int[] ATTRS = new int[]{
           android.R.attr.listDivider
   };
 
   public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;
 
   public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;
 
   private Drawable mDivider;
 
   private int mOrientation;
 
   public DividerItemDecoration(Context context, int orientation) {
       final TypedArray a = context.obtainStyledAttributes(ATTRS);
       mDivider = a.getDrawable(0);
       a.recycle();
       setOrientation(orientation);
   }
 
   public void setOrientation(int orientation) {
       if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
           throw new IllegalArgumentException("invalid orientation");
       }
       mOrientation = orientation;
   }
 
   @Override
   public void onDraw(Canvas c, RecyclerView parent) {
       if (mOrientation == VERTICAL_LIST) {
           drawVertical(c, parent);
       } else {
           drawHorizontal(c, parent);
       }
   }
 
   public void drawVertical(Canvas c, RecyclerView parent) {
       final int left = parent.getPaddingLeft();
       final int right = parent.getWidth() - parent.getPaddingRight();
 
       final int childCount = parent.getChildCount();
       for (int i = 0; i < childCount; i++) {
           final View child = parent.getChildAt(i);
           final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                   .getLayoutParams();
           final int top = child.getBottom() + params.bottomMargin;
           final int bottom = top + mDivider.getIntrinsicHeight();
           mDivider.setBounds(left, top, right, bottom);
           mDivider.draw(c);
       }
   }
 
   public void drawHorizontal(Canvas c, RecyclerView parent) {
       final int top = parent.getPaddingTop();
       final int bottom = parent.getHeight() - parent.getPaddingBottom();
 
       final int childCount = parent.getChildCount();
       for (int i = 0; i < childCount; i++) {
           final View child = parent.getChildAt(i);
           final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                   .getLayoutParams();
           final int left = child.getRight() + params.rightMargin;
           final int right = left + mDivider.getIntrinsicHeight();
           mDivider.setBounds(left, top, right, bottom);
           mDivider.draw(c);
       }
   }
 
   @Override
   public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
       if (mOrientation == VERTICAL_LIST) {
           outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
       } else {
           outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
       }
   }
}