Aligning RecyclerView under LinearLayout

I have a linear layout called "footer". I want to post below mine RecyclerView

(new list type introduced in API 21).

• RecyclerView
  
  would probably want to have height "match_parent"
  
  for efficient memory use (avoid unnecessary computation).
• I don't need to have RecyclerView
  
  it at first , because then it will take up the whole screen and the footer will not be visible.
• Since it RecyclerView
  
  comes in second, linearlayout
  
  shouldn't have a height "match_parent"
  
  because then RecyclerView
  
  it won't be visible and I don't need the footer to stretch anyway.

So, I've got linearlayout

"footer"

the height, first in my root relativelayout

, then RecyclerView

to "match_parent"

the aforesaid "footer":

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin">

<LinearLayout
    android:id="@+id/footer"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/addTaskImage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="end"
        android:src="@drawable/ic_edit"
        android:visibility="visible" />

    <RelativeLayout
        android:id="@+id/addTaskRL"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:visibility="gone">

        <EditText
            android:id="@+id/taskET"
            android:layout_width="match_parent"
            android:layout_height="150sp"
            android:background="@color/White">
        </EditText>

        <RelativeLayout
            android:id="@+id/paletteRed"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_below="@id/taskET"
            android:layout_marginLeft="50dp"
            android:layout_marginTop="10dp"
            android:background="@color/Red" />

        <RelativeLayout
            android:id="@+id/paletteOrange"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_below="@id/taskET"
            android:layout_marginLeft="10dp"
            android:layout_marginTop="10dp"
            android:layout_toRightOf="@id/paletteRed"
            android:background="@color/Orange" />

        <RelativeLayout
            android:id="@+id/paletteGreen"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_below="@id/taskET"
            android:layout_marginLeft="10dp"
            android:layout_marginTop="10dp"
            android:layout_toRightOf="@id/paletteOrange"
            android:background="@color/Green" />

        <RelativeLayout
            android:id="@+id/paletteRoyalBlue"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_below="@id/taskET"
            android:layout_marginLeft="10dp"
            android:layout_marginTop="10dp"
            android:layout_toRightOf="@id/paletteGreen"
            android:background="@color/RoyalBlue" />

        <RelativeLayout
            android:id="@+id/palettePurple"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_below="@id/taskET"
            android:layout_marginLeft="10dp"
            android:layout_marginTop="10dp"
            android:layout_toRightOf="@id/paletteRoyalBlue"
            android:background="@color/Purple" />

        <Button
            android:id="@+id/submitBtn"
            android:layout_width="70dp"
            android:layout_height="30dp"
            android:layout_below="@id/taskET"
            android:layout_marginLeft="10dp"
            android:layout_marginTop="10dp"
            android:layout_toRightOf="@id/palettePurple"
            android:background="@color/SkyBlue"
            android:textColor="@color/White"
            android:text="@string/submit">
        </Button>
    </RelativeLayout>
</LinearLayout>

<android.support.v7.widget.RecyclerView
    android:id="@+id/tasksRV"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_above="@id/footer"/>
</RelativeLayout>

      

        
        
        
      

    

I know this is a layout issue because if I remove the footer, mine is displayed RecyclerView

. What's my misunderstanding of the layouts above?