We Keep Coding

Blank space either side of BottomNavigationView

I'm creating an Android app with a BottomNavigationView and for some reason there is blank space on either side so it doesn't fill the whole width of the screen. It's not padding, because I removed the padding and I can see the shadow of the bottom view separating the blank area from the space above. Why are my four menu items not filling the entire width of the screen?
It looks good when I have three or five items so is this just a limitation of dividing the screen space into even numbers?
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/navigation"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:background="?android:attr/windowBackground"
app:itemBackground="#color/colorPrimary"
app:itemIconTint="#color/colorNavTint"
app:itemTextColor="#color/colorNavText"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:menu="#menu/navigation" />
navigation Menu:
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item
android:id="#+id/navigation_discover"
android:icon="#drawable/ic_discover"
android:title="Discover"/>
<item
android:id="#+id/navigation_search"
android:icon="#drawable/ic_search"
android:title="Search"/>
<item
android:id="#+id/navigation_messages"
android:icon="#drawable/ic_messages"
android:title="Messages"/>
<item
android:id="#+id/navigation_orders"
android:icon="#drawable/ic_orders"
android:title="Orders"/>
</menu>
and the parent ConstraintLayout:
<androidx.constraintlayout.widget.ConstraintLayout 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=".MainActivity">

The first icon on my navigation bar is blue and larger than the others, how do I change that?

Completely new user of Android Studio is here, and I'm trying to make a movie review application as a school project.
So the problem here is that there will be several icons on my homepage's navigation bar, but the first icon for some reason is always blue and larger than the other icons, and I have no idea how to fix that, as you can see in the picture. Picture
Here's the XML of my homepage.xml and the nav_items.xml
HOMEPAGE
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
android:background="#FFFFFF"
tools:context=".Homepage">
<android.support.design.widget.BottomNavigationView
android:layout_width="match_parent"
android:layout_height="68dp"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true"
app:menu="#menu/nav_items"></android.support.design.widget.BottomNavigationView>
</RelativeLayout>
Nav_items.XML
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:android="http://schemas.android.com/apk/res/android">
<item
android:icon="#drawable/ic_input_black_24dp"
android:title="#string/nav_list" />
<item
android:icon="#drawable/outline_home_black_24"
android:title="#string/nav_home" />
</menu>

If it is blue by default then it means it is selected.

Change color of navigation bar selected item

I used
setTheme(R.style.Theme_AppCompat);
to set my app theme darker.
Now I run into that issue that the selected item in my navigationbar is relativly dark, so that users can hardly see it.
Is there anything that I can use in my style to get the selected navigation item in another color?
Here is a picture of it
Here is my activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:ads="http://schemas.android.com/apk/res-auto"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:visibility="visible"
tools:context="at.mrminemeet.asciimoji.MainActivity">
.....
<android.support.design.widget.BottomNavigationView
android:id="#+id/navigation"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="#menu/navigation"/>
</android.support.constraint.ConstraintLayout>

Add the following to your BottomNavigationView:
app:itemIconTint="#drawable/bottom_navigation_selector"
app:itemTextColor="#drawable/bottom_navigation_selector"
In your drawable folder, create a file bottom_navigation_selector.xml and add this to it:
<?xml version="1.0" encoding="utf-8"?>
<selector
xmlns :android="http://schemas.android.com/apk/res/android">
<item android:color="#color/colorAccent" android:state_checked="true"/>
<item android:color="#android:color/darker_gray" android:state_checked="false"/>
</selector>
Finally in every activity where you use this navigation bar add this line to onCreate() and onResume()
bottomNavigationView.setSelectedItemId(R.id.item);

You can specify the BottomNavigationView_itemBackground attribute to your BottomNavigationView, you can set a selector as a background with different colors for the normal and selected states

Layout margin pushing image in ImageView

I am using grid view to display images in my app and I am using CardView for parent element.
I want the CardView to have some space from the beggining of the page and between each CardView so I am setting layout_margin to be 5dp.
I also want to have some space between the image and the beggining of the CardView so I put contentPadding to be 10dp.
The result though is not what I want. It seems that the layout_margin is pushing the image itself and the padding for the right side is not 10dp as I want but 10dp - 5dp and I really have no clue how to fix that
Here is visual examples:
And this is the result I get:
You can see the right side of the CardView and how the image is not properly centered.
Thank you for your help!
Edit:
ImageViewStyle:
<style name="ImageViewStyle">
<item name="android:layout_width">fill_parent</item>
<item name="android:layout_height">#dimen/card_view_image_view_height</item>
<item name="android:layout_gravity">center</item>
<item name="android:layout_alignParentTop">true</item>
<item name="android:scaleType">centerCrop</item>
</style>

Try this:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.CardView
android:layout_width="120dp"
android:layout_height="120dp"
android:layout_margin="5dp"
app:cardCornerRadius="2dp">
<ImageView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center"
android:layout_margin="10dp"
android:background="#drawable/image"/>
</android.support.v7.widget.CardView>

Set color item listview xml

i've a Navigation Drawer and i would like that when i click on an item of the listview this change color. So i've this xml code.
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/navigation_drawer"
android:layout_width="match_parent"
android:layout_height="match_parent">
<FrameLayout
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<ListView
android:id="#+id/listview"
android:layout_width="240dp"
android:layout_height="match_parent"
android:layout_gravity="start"
android:choiceMode="singleChoice"
android:textColor="#drawable/test"
android:divider="#null"
android:dividerHeight="0dp"
android:background="#2F2F2F"/>
</android.support.v4.widget.DrawerLayout>
Test code is
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_selected="true" android:color="#android:color/black"/>
<item android:state_focused="true" android:color="#android:color/black"/>
<item android:state_pressed="true" android:color="#android:color/black"/>
<item android:color="#android:color/black"/>
</selector>
But when i click remain the default color and not change in black. Why? Where is the problem and how can i fix it? Thanks in advance.

It's because you are changing the textColor of a textView not the view inside the ListView. It's not like css.
You must put android:textColor="#drawable/test" inside the TextView (or whatever view it is)

use android:listSelector="color/black" in your listview. Refer here