Add floating point value to android resources/values

Question

There is a solution:

<resources>
    <item name="text_line_spacing" format="float" type="dimen">1.0</item>
</resources>

In this way, your float number will be under @dimen. Notice that you can use other "format" and/or "type" modifiers, where format stands for:

Format = enclosing data type:

• float
• boolean
• fraction
• integer
• ...

and type stands for:

Type = resource type (referenced with R.XXXXX.name):

• color
• dimen
• string
• style
• etc...

To fetch resource from code, you should use this snippet:

TypedValue outValue = new TypedValue();
getResources().getValue(R.dimen.text_line_spacing, outValue, true);
float value = outValue.getFloat();  

I know that this is confusing (you'd expect call like getResources().getDimension(R.dimen.text_line_spacing)), but Android dimensions have special treatment and pure "float" number is not valid dimension.

---

Additionally, there is small "hack" to put float number into dimension, but be WARNED that this is really hack, and you are risking chance to lose float range and precision.

<resources>
    <dimen name="text_line_spacing">2.025px</dimen>
</resources>

and from code, you can get that float by

float lineSpacing = getResources().getDimension(R.dimen.text_line_spacing);

in this case, value of lineSpacing is 2.024993896484375, and not 2.025 as you would expected.

As described in this link http://droidista.blogspot.in/2012/04/adding-float-value-to-your-resources.html

Declare in dimen.xml

<item name="my_float_value" type="dimen" format="float">9.52</item>

Referencing from xml

@dimen/my_float_value

Referencing from java

TypedValue typedValue = new TypedValue();
getResources().getValue(R.dimen.my_float_value, typedValue, true);
float myFloatValue = typedValue.getFloat();

All the solutions suggest you to use the predefined float value through code.

But in case you are wondering how to reference the predefined float value in XML (for example layouts), then following is an example of what I did and it's working perfectly:

Define resource values as type="integer" but format="float", for example:

<item name="windowWeightSum" type="integer" format="float">6.0</item>
<item name="windowNavPaneSum" type="integer" format="float">1.5</item>
<item name="windowContentPaneSum" type="integer" format="float">4.5</item>

And later use them in your layout using @integer/name_of_resource, for example:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:weightSum="@integer/windowWeightSum"                 // float 6.0
    android:orientation="horizontal">

    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="@integer/windowNavPaneSum"        // float 1.5
        android:orientation="vertical">
        <!-- other views -->
    </LinearLayout>

    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="@integer/windowContentPaneSum"    // float 4.5
        android:orientation="vertical">
        <!-- other views -->
    </LinearLayout>

</LinearLayout>

Add a float to dimens.xml:

<item format="float" name="my_dimen" type="dimen">1.2</item>

To reference from XML:

<EditText 
    android:lineSpacingMultiplier="@dimen/my_dimen"
    ...

To read this value programmatically you can use ResourcesCompat.getFloat from androidx.core

Gradle dependency:

implementation("androidx.core:core:${version}")

Usage:

import androidx.core.content.res.ResourcesCompat;

...

float value = ResourcesCompat.getFloat(context.getResources(), R.dimen.my_dimen);

I also found a workaround which seems to work fine with no warnings:

<resources>
    <item name="the_name" type="dimen">255%</item>
    <item name="another_name" type="dimen">15%</item>
</resources>

Then:

// theName = 2.55f
float theName = getResources().getFraction(R.dimen.the_name, 1, 1);
// anotherName = 0.15f
float anotherName = getResources().getFraction(R.dimen.another_name, 1, 1);

Warning : it only works when you use the dimen from Java code not from xml

We can also use it for the guideline of the constraint layout.

Create integer.xml file and add into

 <item name="guideline_button_top" type="integer" format="float">0.60</item>

Use from a layout.xml file

 app:layout_constraintGuide_percent="@integer/guideline_button_top" 

I used a style to solve this issue. The official link is here.

Pretty useful stuff. You make a file to hold your styles (like "styles.xml"), and define them inside it. You then reference the styles in your layout (like "main.xml").

Here's a sample style that does what you want:

<style name="text_line_spacing">
   <item name="android:lineSpacingMultiplier">1.4</item>
</style>

Let's say you want to alter a simple TextView with this. In your layout file you'd type:

<TextView
   style="@style/summary_text"
   ...
   android:text="This sentence has 1.4 times more spacing than normal."
/>

Try it--this is essentially how all the built-in UI is done on the android. And by using styles, you have the option to modify all sorts of other aspects of your Views as well.