How to remove extra borders around the toolbar after adding margin?

Question

I've added a Toolbar at the top of my layout but after I set margin for it, Some extra borders will appear around my toolbar and i think it's because of the ActionBar's attributes. I want to remove these extra borders but I don't know how to do it. What should i do now? Thank you in advance :)

Screenshot:

This is my XML code:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context="realup.ir.teacher.Activity.Main"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/realupbackground_co">

    <android.support.design.widget.CoordinatorLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/header">

        <android.support.design.widget.AppBarLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/app_bar_head">

            <android.support.v7.widget.Toolbar
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="#edeaed"
                android:titleTextColor="#89798a"
                android:id="@+id/toolbar"
                app:layout_scrollFlags="scroll|enterAlways"
                android:layout_margin="@dimen/normal_margin"/>

            <android.support.design.widget.CollapsingToolbarLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                app:layout_scrollFlags="scroll|exitUntilCollapsed"
                android:id="@+id/collapse_toolbar"
                app:titleEnabled="true">


                <ImageView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:adjustViewBounds="true"
                    android:scaleType="centerCrop"
                    android:src="@drawable/course_page_cover"
                    android:id="@+id/header_image" />


            </android.support.design.widget.CollapsingToolbarLayout>

        </android.support.design.widget.AppBarLayout>

        <android.support.v4.widget.NestedScrollView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_behavior="@string/appbar_scrolling_view_behavior">

            <android.support.v7.widget.RecyclerView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:id="@+id/recycle"/>

        </android.support.v4.widget.NestedScrollView>

    </android.support.design.widget.CoordinatorLayout>

</RelativeLayout>

This is the Java code for Toolbar:

Toolbar toolbar = (Toolbar) rootView.findViewById(R.id.toolbar);
    ((AppCompatActivity)getActivity()).setSupportActionBar(toolbar);
    toolbar.setTitle("Real Up");
 toolbar.setTitleTextColor(getResources().getColor(R.color.TitlColor,null));

Answer 1

Check this answer:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context="realup.ir.teacher.Activity.Main"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/realupbackground_co">

    <android.support.design.widget.CoordinatorLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/header">

        <android.support.design.widget.AppBarLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="@dimen/normal_margin"
            android:id="@+id/app_bar_head">

            <android.support.v7.widget.Toolbar
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="#edeaed"
                android:titleTextColor="#89798a"
                android:id="@+id/toolbar"
                app:layout_scrollFlags="scroll|enterAlways"/>

            <android.support.design.widget.CollapsingToolbarLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                app:layout_scrollFlags="scroll|exitUntilCollapsed"
                android:id="@+id/collapse_toolbar"
                app:titleEnabled="true">


                <ImageView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:adjustViewBounds="true"
                    android:scaleType="centerCrop"
                    android:src="@drawable/course_page_cover"
                    android:id="@+id/header_image" />


            </android.support.design.widget.CollapsingToolbarLayout>

        </android.support.design.widget.AppBarLayout>

    </android.support.design.widget.CoordinatorLayout>
    <android.support.v4.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_below="@+id/header"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</android.support.v4.widget.NestedScrollView>

</RelativeLayout>