Android GridView draw dividers

Solution 1:

In case you want just simple lines as borders, much, much simpler is setting a background color for a GridView and proper padding & spacing:

<GridView
    (...)
    android:background="@color/LightGold"
    android:listSelector="@android:color/transparent"
    android:horizontalSpacing="1dip"
    android:verticalSpacing="1dip"
    android:paddingLeft="1dip"
    android:paddingTop="1dip" />

Solution 2:

Unfortunately, after looking at the source code, I could not see any easy way to add borders other than taking the approach of adding borders to the each cell. As a reference, I will post my solution here.

list_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="horizontal"
    android:background="@drawable/list_selector">

    <!-- Cell contents -->

</LinearLayout>

list_selector.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item 
        android:state_selected="true" 
        android:drawable="@drawable/item_border_selected" 
    />
    <item 
        android:state_pressed="true" 
        android:drawable="@drawable/item_border_selected" 
    />
    <item
        android:drawable="@drawable/item_border" 
    />
</selector>

item_border.xml

<?xml version="1.0" encoding="UTF-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid 
        android:color="@android:color/transparent" 
    />
    <stroke 
        android:width="1px" 
        android:color="@color/list_divider" 
    />
</shape>

item_border_selected.xml

<?xml version="1.0" encoding="UTF-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid 
        android:color="@color/list_select" 
    />
    <stroke 
        android:width="1px" 
        android:color="@color/list_divider" 
    />
</shape>

items_view.xml

<?xml version="1.0" encoding="utf-8"?>
<GridView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_marginLeft="-1px"
    android:layout_marginRight="-1px"
    android:listSelector="@android:color/transparent"
/>

Since all lines double in size as they join their neighboring cells, I made the divider size 1px instead of 1dp so it doesn't appear too large on some screens. Also, I made the grid view have negative margins to hide the lines on either side. I hope this helps someone.