remove default margin bottom from Toolbar

Question

In my application I use the android.support.v7.widget.Toolbar for the toolbar.

Here is my layout

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.todo.app.MainActivity"
style="@style/MainActivityBg">

<android.support.design.widget.AppBarLayout
    android:layout_height="wrap_content"
    android:layout_width="match_parent">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        android:elevation="4dp"
        android:theme="@style/AppTheme.AppBarOverlay"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
        style="@style/AppTheme.ActionBar"/>

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

<include layout="@layout/content_main"/>

and

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
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"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:showIn="@layout/activity_main"
tools:context="com.todo.app.MainActivity"
android:layout_marginTop="5dp">  <!-- for adding some space between the toolbar and the rest, and this is the cause of the problem! -->

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

I try to add some space between the toolbar and the rest of the view. To do that I added 5dp in marginTop to the layout which is right under the view. And this causes this problem: While I scrolling the view there is some space remaining under the toolbar.

In my style files xml, there is no style for margin or padding. How I can adding some space between toolbar and the rest without trigger this problem (when I scrolling the view)?

Answer 1

Reason

Based on the xml files, it seems to me that:

<android.support.constraint.ConstraintLayout
    ...
    android:layout_marginTop="5dp"> 

is the reason for cropping RecyclerView content.

When you set the layout_marginTop between the AppBarLayout and the upper edge of ConstraintLayout appears a 5dp high empty space.

You can confirm that by turning on one of the Android options for developers: Show Layout Bounds.

Solution

For the effect which you want to achieve try to remove android:layout_marginTop and set android:paddingTop for the RecyclerView but also set android:clipToPadding to false. Check the gif in this SO answer.

<android.support.v7.widget.RecyclerView
    android:id="@+id/task_list"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingTop="5dp"
    android:clipToPadding="false" />

This will allow you to add the desired space at the beginning of scrollable content but prevent cropping the items.