How can a divider line be added in an Android RecyclerView?

Question

I am developing an android application where I am using RecyclerView. I need to add a divider in RecyclerView. I tried to add -

recyclerView.addItemDecoration(new
     DividerItemDecoration(getActivity(),
       DividerItemDecoration.VERTICAL_LIST));

below is my xml code -

   <android.support.v7.widget.RecyclerView
    android:id="@+id/drawerList"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="15dp"
    />

Alaric

i guees this will help you https://mcmap.net/q/27078/-how-to-add-dividers-and-spaces-between-items-in-recyclerview/942224 – Fixative

To show divider without the last line, use this – Council

I think your code is correct. I don't see any problem. – Reaction

Answer 1

In the October 2016 update, the support library v25.0.0 now has a default implementation of basic horizontal and vertical dividers available!

https://developer.android.com/reference/android/support/v7/widget/DividerItemDecoration.html

 recyclerView.addItemDecoration(new DividerItemDecoration(recyclerView.getContext(), DividerItemDecoration.VERTICAL));

Triboluminescent

Hi thanks for the information! Is there a way to remove the divider after the last item? I just have a CardView where the List is implemented and the divider + shadow of cardview at the bottom looks not good! – Secessionist

I had the same problem, and solved it by extending DividerItemDecoration and overriding getItemOffsets, then only calling super if I'm not on the first item. if(parent.getChildAdapterPosition(view) == state.getItemCount() - 1) then return, else call the superclass' getItemOffsets(). – Thurlough

Instead of mLayoutManager.getOrientation(), I used DividerItemDecoration.VERTICAL and it worked, since my RecyclerView is vertical. – Whyalla

is there a way to change the color of the divider using this built in way ? – Leshia

Be careful using this approach on older devices running Android 6 or older, the line was not visible for me on these devices. – Beluga

@V.Kalyuzhnyu @android:attr/listDivider in app theme doesn't display a divider if it's a color resource, I had to create a shape drawable with my color with a fixed height. – Priorate

Answer 2

The Right way is to define ItemDecoration for the RecyclerView is as following

SimpleDividerItemDecoration.java

public class SimpleDividerItemDecoration extends RecyclerView.ItemDecoration {
    private Drawable mDivider;
 
    public SimpleDividerItemDecoration(Context context) {
        mDivider = ContextCompat.getDrawable(context, R.drawable.line_divider);
    }
 
    @Override
    public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int left = parent.getPaddingLeft();
        int right = parent.getWidth() - parent.getPaddingRight();
 
        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = parent.getChildAt(i);
 
            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
 
            int top = child.getBottom() + params.bottomMargin;
            int bottom = top + mDivider.getIntrinsicHeight();
 
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }
}

Or If you are using kotlin: SimpleDividerItemDecoration.kt

class SimpleDividerItemDecoration(context: Context, @DrawableRes dividerRes: Int) : ItemDecoration() {

    private val mDivider: Drawable = ContextCompat.getDrawable(context, dividerRes)!!

    override fun onDrawOver(c: Canvas, parent: RecyclerView) {
        val left = parent.paddingLeft
        val right = parent.width - parent.paddingRight
        val childCount = parent.childCount
        for (i in 0 until childCount) {
            val child: View = parent.getChildAt(i)
            val params = child.layoutParams as RecyclerView.LayoutParams
            val top: Int = child.bottom + params.bottomMargin
            val bottom = top + mDivider.intrinsicHeight
            mDivider.setBounds(left, top, right, bottom)
            mDivider.draw(c)
        }
    }
}
    

line_divider.xml:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
 
    <size
        android:width="1dp"
        android:height="1dp" />
 
    <solid android:color="@color/dark_gray" />
 
</shape>

Finally set it like this

recyclerView.addItemDecoration(new SimpleDividerItemDecoration(this));

---

Edit

As pointed out by @Alan S.

context.getResources().getDrawable(R.drawable.line_divider); 

is depreciated instead of that you can use

ContextCompat.getDrawable(context,R.drawable.line_divider);

Sondra

This is perfectly working on my side. However, I wonder why not add a simple <View> for this separator into the layout for each cell? Its much less code. Is this solution less good performance wise? tx – Weitzel

Problem with this implementation arises if you try to are swiping or moving items around. – Happy

Thank you very much! Works perfectly.. However is there a way to remove the divider after the last item? I tried overriding getItemOffsets like the answers below, but none of the below implementations worked for me. – Turn

I'm new to developing on android, and this solution works, so please help me understand why this is the "right" way. This solution feels like a violation of separation between view and models. There is so much linkage code necessary to make this work instead of just defining a 'line' in the xml view definition. Why programmatically add the line? – Hanlon

@Hanlon this answer was posted long ago. when there was no default implementation for the dividers were provided by Android API's You can use default implementation of basic horizontal and vertical dividers available at official site. developer.android.com/reference/android/support/v7/widget/… – Sondra

Answer 3

If you want to have both horizontal and vertical dividers:

1. Define horizontal & vertical divider drawables:

   horizontal_divider.xml

   <?xml version="1.0" encoding="utf-8"?>
   <shape xmlns:android="http://schemas.android.com/apk/res/android" >
     <size android:height="1dip" />
     <solid android:color="#22000000" />
   </shape>
   

   vertical_divider.xml

   <?xml version="1.0" encoding="utf-8"?>
   <shape xmlns:android="http://schemas.android.com/apk/res/android" >
       <size android:width="1dip" />
       <solid android:color="#22000000" />
   </shape>
   

2. Add this code segment below:

   DividerItemDecoration verticalDecoration = new DividerItemDecoration(recyclerview.getContext(),
           DividerItemDecoration.HORIZONTAL);
   Drawable verticalDivider = ContextCompat.getDrawable(getActivity(), R.drawable.vertical_divider);
   verticalDecoration.setDrawable(verticalDivider);
   recyclerview.addItemDecoration(verticalDecoration);
   
   DividerItemDecoration horizontalDecoration = new DividerItemDecoration(recyclerview.getContext(),
           DividerItemDecoration.VERTICAL);
   Drawable horizontalDivider = ContextCompat.getDrawable(getActivity(), R.drawable.horizontal_divider);
   horizontalDecoration.setDrawable(horizontalDivider);
   recyclerview.addItemDecoration(horizontalDecoration);
   

Grogshop

It worked. But if you change horizontal_divider.xml to divide width and vertical_divider.xml to divide height, you could create each DividerItemDecoration like this: verticalDecoration = new DividerItemDecoration(recyclerview.getContext(), DividerItemDecoration.VERTICAL); and horizontalDecoration = new DividerItemDecoration(recyclerview.getContext(), DividerItemDecoration.HORIZONTAL);. – Rawdan

Answer 4

Just add a View by the end of you item adapter:

<View
 android:layout_width="match_parent"
 android:layout_height="1dp"
 android:background="#FFFFFF"/>

Pyxie

With this solution you will get also the divider line at the end of the list. – Nursling

The last line can be removed programatically by saying something like this in onBindViewHolder if(position == getItemCount() - 1) { mDividerView.setVisibility(View.INVISIBLE) } Or there must be other ways to do this. – Perimorph

most of the time, the last line with 1px of height, is invisible to our eyes – Monandrous

@LucasDiego This will work but we know that inflating is expensive. – Sparky

This is not the best possible solution as it works fine only if there are not too many elements in the RecyclerView. Otherwise, the View will not be drawn for every element. So please go with DividerItemDecoration. – Pug

Answer 5

All of these answers got me close but they were each missing a key detail. After a bit of research, I found the easiest route to be a combination of these 3 steps:

1. Use the support library's DividerItemDecoration
2. Create a divider with the right color
3. Set this divider in your theme as the listDivider

---

Step 1: while configuring RecyclerView

recyclerView.addItemDecoration(
        new DividerItemDecoration(context, layoutManager.getOrientation()));

Step 2: in a file like res/drawable/divider_gray.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <size android:width="1px" android:height="1px" />
    <solid android:color="@color/gray" />
</shape>

Step 3: in the app's theme

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
    <!-- Other theme items above -->
    <item name="android:listDivider">@drawable/divider_gray</item>
</style>

---

EDIT: Updated to skip last divider:
After using this a bit, I realized it was drawing a divider after the last item, which was annoying. So I modified Step 1 as follows to override that default behavior in DividerItemDecoration (of course, making a separate class is another option):

recyclerView.addItemDecoration(
        new DividerItemDecoration(context, layoutManager.getOrientation()) {
            @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);
                }
            }
        }
);

Paragraph

Overriding getItemOffsets doesn't seem to work for me. Even if I override and never call super, the divider is still drawn. Not sure what changed. – Demount

It doesn't work for me either. The last divider still showing. – Reis

I ended up create my own divider class by copying the source of DividerItemDecoration, and change a bit to not drawing the last dividier. In drawing method, just ignore the last child view: for (int i = 0; i < childCount; i++) change to for (int i = 0; i < childCount - 1; i++) – Sexdecillion

Since ItemDecoration is drawn before list item ("under" list item), given solution works only if your list item has 100% opaque background, or when decoration drawable is 100% transparent (so the user sees recyclerView's background). Otherwise the divider is visible no matter what you return in getItemOffsets() – Marseilles

Answer 6

Here is the code for a simple custom divider (vertical divider / 1dp height / black ):

It suppose you have Support Library:

compile "com.android.support:recyclerview-v7:25.1.1"

java code

    DividerItemDecoration divider = new DividerItemDecoration(recyclerView.getContext(), DividerItemDecoration.VERTICAL);
    divider.setDrawable(ContextCompat.getDrawable(getBaseContext(), R.drawable.my_custom_divider));
    recyclerView.addItemDecoration(divider);

then the custom_divider.xml file sample :

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
    <size android:height="1dp" />
    <solid android:color="@android:color/black" />
</shape>

Scutari

Answer 7

Kotlin Version:

recyclerview.addItemDecoration(DividerItemDecoration(this, LinearLayoutManager.VERTICAL))

Rolan

Answer 8

The way how I'm handling the Divider view and also Divider Insets is by adding a RecyclerView extension.

1.

Add a new extension file by naming View or RecyclerView:

RecyclerViewExtension.kt

and add the setDivider extension method inside the RecyclerViewExtension.kt file.

/*
* RecyclerViewExtension.kt
* */
import androidx.annotation.DrawableRes
import androidx.core.content.ContextCompat
import androidx.recyclerview.widget.DividerItemDecoration
import androidx.recyclerview.widget.RecyclerView


fun RecyclerView.setDivider(@DrawableRes drawableRes: Int) {
    val divider = DividerItemDecoration(
        this.context,
        DividerItemDecoration.VERTICAL
    )
    val drawable = ContextCompat.getDrawable(
        this.context,
        drawableRes
    )
    drawable?.let {
        divider.setDrawable(it)
        addItemDecoration(divider)
    }
}

2.

Create a Drawable resource file inside of drawable package like recycler_view_divider.xml:

<inset xmlns:android="http://schemas.android.com/apk/res/android"
    android:insetLeft="10dp"
    android:insetRight="10dp">

    <shape>
        <size android:height="0.5dp" />
        <solid android:color="@android:color/darker_gray" />
    </shape>

</inset>

where you can specify the left and right margin on android:insetLeft and android:insetRight.

3.

On your Activity or Fragment where the RecyclerView is initialized, you can set the custom drawable by calling:

recyclerView.setDivider(R.drawable.recycler_view_divider)

4.

Cheers 🍺

Rennin

Answer 9

Create a seperate xml file in res/drawable folder

 <?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
    <size android:height="1dp" />
    <solid android:color="@android:color/black" />
</shape>

Connect that xml file (your_file) at the main activity, like this:

DividerItemDecoration divider = new DividerItemDecoration(
    recyclerView.getContext(),
    DividerItemDecoration.VERTICAL
);
divider.setDrawable(ContextCompat.getDrawable(getBaseContext(), R.drawable.your_file));
recyclerView.addItemDecoration(divider);

Wardwarde

How to add padding? Using padding in shape doesn't work. – Words

Answer 10

Try this simple single line code

recyclerView.addItemDecoration(new DividerItemDecoration(getContext(),LinearLayoutManager.VERTICAL)); 

Veinlet

Answer 11

So this might not be the correct way, but I just added a view to the single item view of the RecyclerView (as I don't think there is a built-in function) like so:

<View
    android:layout_width="fill_parent"
    android:layout_height="@dimen/activity_divider_line_margin"
    android:layout_alignParentBottom="true"
    android:background="@color/tasklist_menu_dividerline_grey" />

This means each item will have a line which fills it at its bottom. I made it about 1dp high with a #111111 background. This also gives it a kind of "3D" effect.

Glazer

-- this is not a way – Moldy

Answer 12

I think you are using Fragments to have RecyclerView

Simply add these lines after creating your RecyclerView and LayoutManager Objects

DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(recyclerView.getContext(),
                DividerItemDecoration.VERTICAL);
        recyclerView.addItemDecoration(dividerItemDecoration);

Thats it!

It supports both HORIZONTAL and VERTICAL orientations.

Somber

Answer 13

You need add next line...

mRecyclerView.addItemDecoration(new DividerItemDecoration(getContext(), DividerItemDecoration.VERTICAL));

Tetragram

Answer 14

You can create a simple reusable divider.

Create Divider:

public class DividerItemDecorator extends RecyclerView.ItemDecoration {
    private Drawable mDivider;

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

    @Override
    public void onDraw(Canvas canvas, RecyclerView parent, RecyclerView.State state) {
        int dividerLeft = parent.getPaddingLeft();
        int dividerRight = parent.getWidth() - parent.getPaddingRight();

        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = parent.getChildAt(i);

            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();

            int dividerTop = child.getBottom() + params.bottomMargin;
            int dividerBottom = dividerTop + mDivider.getIntrinsicHeight();

            mDivider.setBounds(dividerLeft, dividerTop, dividerRight, dividerBottom);
            mDivider.draw(canvas);
        }
    }
}

Create Divider Line: divider.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <size
        android:width="1dp"
        android:height="1dp" />
    <solid android:color="@color/grey_300" />
</shape>

Add divider to your Recyclerview:

RecyclerView.ItemDecoration dividerItemDecoration = new DividerItemDecorator(ContextCompat.getDrawable(context, R.drawable.divider));
recyclerView.addItemDecoration(dividerItemDecoration);

To remove divider for the last item:

To prevent divider drawing for the last item you have to change this line.

for (int i = 0; i < childCount; i++) 

To

for (int i = 0; i < childCount-1; i++)

Your final implementation should be like this:

public class DividerItemDecorator extends RecyclerView.ItemDecoration {
    private Drawable mDivider;

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

    @Override
    public void onDraw(Canvas canvas, RecyclerView parent, RecyclerView.State state) {
        int dividerLeft = parent.getPaddingLeft();
        int dividerRight = parent.getWidth() - parent.getPaddingRight();

        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount - 1; i++) {
            View child = parent.getChildAt(i);

            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();

            int dividerTop = child.getBottom() + params.bottomMargin;
            int dividerBottom = dividerTop + mDivider.getIntrinsicHeight();

            mDivider.setBounds(dividerLeft, dividerTop, dividerRight, dividerBottom);
            mDivider.draw(canvas);
        }
    }
}

Hope it helps:)

Edgy

This works perfectly I don't know why it is not the accepted answer – Girder

Answer 15

Android just makes little things too complicated unfortunately. Easiest way to achieve what you want, without implementing DividerItemDecoration here:

Add background color to the RecyclerView to your desired divider color:

<RecyclerView
    android:id="@+id/rvList"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:divider="@color/colorLightGray"
    android:scrollbars="vertical"
    tools:listitem="@layout/list_item"
    android:background="@android:color/darker_gray"/>

Add bottom margin (android:layout_marginBottom) to the layout root of the item (list_item.xml):

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_marginBottom="1dp">

    <TextView
        android:id="@+id/tvName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="John Doe" />

    <TextView
        android:id="@+id/tvDescription"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/tvName"
        android:text="Some description blah blah" />

</RelativeLayout>

This should give 1dp space between the items and the background color of RecyclerView (which is dark gray would appear as divider).

Hy

That one's the most elegant way to create a simple divider without adding extra lines of code – Grapery

Answer 16

yqritc's RecyclerView-FlexibleDivider makes this a one liner. First add this to your build.gradle:

compile 'com.yqritc:recyclerview-flexibledivider:1.4.0' // requires jcenter()

Now you can configure and add a divder where you set your recyclerView's adapter:

recyclerView.setAdapter(myAdapter);
recyclerView.addItemDecoration(new HorizontalDividerItemDecoration.Builder(this).color(Color.RED).sizeResId(R.dimen.divider).marginResId(R.dimen.leftmargin, R.dimen.rightmargin).build());

Breckenridge

@Gaurav, Where is the HorizontalDividerItemDecoration class located? – Gaudette

@iRuth, You need to add the maven library into your .gradle file github.com/yqritc/RecyclerView-FlexibleDivider – Jumna

This is an incomplete answer. Maybe a down vote is appropriate. – Downward

It's good to mention that 3-rd party lib required for that @gaurav-vachhani – Ytterbia

Answer 17

recyclerview.addItemDecoration(new DividerItemDecoration(this, LinearLayoutManager.HORIZONTAL));

for vertical line use LinearLayoutManager.VERTICAL

Muskogean

better use the constant variable as the value might change on the future release of the support library – Misdoing

true.. we should use LinearLayoutManager.HORIZONTAL or LinearLayoutManager.VERTICAL instead of 0 or 1 – Muskogean

Answer 18

i think its the easiest way

mDividerItemDecoration = new DividerItemDecoration(recyclerView.getContext(),
                DividerItemDecoration.VERTICAL);
// or DividerItemDecoration.HORIZONTALL
        mDividerItemDecoration.setDrawable(getDrawable(R.drawable.myshape));
        recyclerView.addItemDecoration(mDividerItemDecoration);

Note that : myshape can be rectangel with height you want to make your divider

Pennebaker

Answer 19

KOTLIN - If you are looking for custom color divider between recycler view items, then here is the solution which works for me:

Step 1 : Give your recycler view a default item decoration. recyclerView.addItemDecoration(androidx.recyclerview.widget.DividerItemDecoration(activity, androidx.recyclerview.widget.LinearLayoutManager.VERTICAL))

Step 2 : Add a xml drawable specifying the size - width and height with the color you want.

<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <size
        android:width="1dp"
        android:height="1dp" />
    <solid android:color="@color/your_color" />
</shape>

Step 3 : Add this line in your app theme.

<item name="android:listDivider">@drawable/your_drawable</item>

Diffractometer

Answer 20

To make N J's answer a little simpler you can do:

public class DividerColorItemDecoration extends DividerItemDecoration {

    public DividerColorItemDecoration(Context context, int orientation) {
        super(context, orientation);
        setDrawable(ContextCompat.getDrawable(context, R.drawable.line_divider));
    }
}

Pantywaist

Answer 21

Simply add a margin of x amount at the bottom of an item in your RecycleView Adapter.

onCreateViewHolder

LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(
                LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);

layoutParams.setMargins(0, 0, 0, 5);
itemView.setLayoutParams(layoutParams);

Morell

Answer 22

  class ItemOffsetDecoration(
        context: Context,
        private val paddingLeft: Int,
        private val paddingRight: Int
    ) : RecyclerView.ItemDecoration() {
        private var mDivider: Drawable? = null

        init {
            mDivider = ContextCompat.getDrawable(context, R.drawable.divider_medium)
        }

        override fun onDrawOver(c: Canvas, parent: RecyclerView, state: RecyclerView.State) {
            val left = parent.paddingLeft + paddingLeft
            val right = parent.width - parent.paddingRight - paddingRight
            val childCount = parent.childCount
            for (i in 0 until childCount) {
                val child = parent.getChildAt(i)
                val params = child.layoutParams as RecyclerView.LayoutParams
                val top = child.bottom + params.bottomMargin
                val bottom = top + (mDivider?.intrinsicHeight ?: 0)

                mDivider?.let {
                    it.setBounds(left, top, right, bottom)
                    it.draw(c)
                }
            }
        }
    }

You just need to specify a color in R.drawable.divider_medium

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid android:color="@android:color/black" />
    <size
        android:height="1dp"
        android:width="1dp" />

</shape>

and add it to your recyclerView

recyclerView.addItemDecoration(
                        ItemOffsetDecoration(
                            this,
                            resources.getDimension(resources.getDimension(R.dimen.dp_70).roundToInt()).roundToInt(),
                            0
                        )
                    )

refernce this

Detergency

Answer 23

MaterialDividerItemDecoration from Material-IO library is a complete solution for many use cases like list item division or section division. It has everything a developer may need like insets and styling without implementing your own item decoration. This Material Divider guide + implementation is really good to check.

Gomar

Answer 24

Bhuvanesh BS solution works. Kotlin version of this:

import android.graphics.Canvas
import android.graphics.drawable.Drawable
import androidx.recyclerview.widget.RecyclerView

class DividerItemDecorator(private val mDivider: Drawable?) : RecyclerView.ItemDecoration() {

    override fun onDraw(
        canvas: Canvas,
        parent: RecyclerView,
        state: RecyclerView.State
    ) {

        val dividerLeft = parent.paddingLeft
        val dividerRight = parent.width - parent.paddingRight
        for (i in 0 until parent.childCount - 1) {
            val child = parent.getChildAt(i)
            val dividerTop =
                child.bottom + (child.layoutParams as RecyclerView.LayoutParams).bottomMargin
            val dividerBottom = dividerTop + mDivider!!.intrinsicHeight
            mDivider.setBounds(dividerLeft, dividerTop, dividerRight, dividerBottom)
            mDivider.draw(canvas)
        }
    }
}

Wicked

Answer 25

Alright, if don't need your divider color to be changed just apply alpha to the divider decorations.

Example for GridLayoutManager with transparency:

DividerItemDecoration horizontalDividerItemDecoration = new DividerItemDecoration(WishListActivity.this,
                DividerItemDecoration.HORIZONTAL);
        horizontalDividerItemDecoration.getDrawable().setAlpha(50);
        DividerItemDecoration verticalDividerItemDecoration = new DividerItemDecoration(WishListActivity.this,
                DividerItemDecoration.VERTICAL);
        verticalDividerItemDecoration.getDrawable().setAlpha(50);
        my_recycler.addItemDecoration(horizontalDividerItemDecoration);
        my_recycler.addItemDecoration(verticalDividerItemDecoration);

You can still change the color of dividers by just setting color filters to it.

Example for GridLayoutManager by setting tint:

DividerItemDecoration horizontalDividerItemDecoration = new DividerItemDecoration(WishListActivity.this,
                DividerItemDecoration.HORIZONTAL);
        horizontalDividerItemDecoration.getDrawable().setTint(getResources().getColor(R.color.colorAccent));
        DividerItemDecoration verticalDividerItemDecoration = new DividerItemDecoration(WishListActivity.this,
                DividerItemDecoration.VERTICAL);
        verticalDividerItemDecoration.getDrawable().setAlpha(50);
        my_recycler.addItemDecoration(horizontalDividerItemDecoration);
        my_recycler.addItemDecoration(verticalDividerItemDecoration);

Additionally you can also try setting color filter,

 horizontalDividerItemDecoration.getDrawable().setColorFilter(colorFilter);

Vindicate