Using custom attributes in layout crashes app

Question

I'm building an Android app and I'm trying to apply a custom theming, and I want to use some custom attributes.

I've defined the attrs in the attrs.xml as such:

<resources>
    <attr name="baseColor" format="reference" />
    <attr name="accentColor" format="reference" />
</resources>

and in my styles.xml I've added the following values to my theme:

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
        <item name="windowActionBar">false</item>
        <item name="android:textColor">@android:color/black</item>
        <item name="android:windowNoTitle">true</item>
        <item name="colorAccent">@color/blue_color</item>
        <item name="android:colorPrimaryDark" tools:targetApi="lollipop">@color/blue_color</item>

        <item name="baseColor">@color/blue_color</item>
        <item name="accentColor">@color/red_color</item>
</style>

Finally, in my XML layout, I'm applying these attributes on a button as such:

<androidx.appcompat.widget.AppCompatButton
            android:id="@+id/sign_up_button"
            android:background="?attr/accentColor"
            android:textColor="?attr/baseColor"
            android:layout_width="match_parent"
            android:layout_height="40dp"
            android:text="@string/sign_up_button" />

However, when I run my app, it crashes with a java.lang.UnsupportedOperationException: Failed to resolve attribute at index 13: TypedValue{t=0x2/d=0x7f040046 a=-1} which of course means that my custom attribute was not found. Am I missing anything? I've already defined the colors and the attrs in my theme, and I've applied the theme to my activity in my manifest. The full stack trace can be found here

@GabeSechan I've updated my question with the full stack trace — Lucas P., Jan 10 '20 at 16:50

score 4 · Accepted Answer · answered Jan 13 '20 at 22:46

4

So it turns out the activity that was crashing was using a different theme, which did not have the custom attributes. I've removed the custom theme form the manifest and the attributes work as expected since they are defined in my App's global theme.

answered Jan 13 '20 at 22:46

Lucas P.

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C. Skjerdal · Answer 2 · 2020-01-10T17:00:20.247

-1

For your custom button you need to declare styleable in attrs.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <declare-styleable name="UpdateButton">
    <attr name="setType" format="string" />
    <attr name="setContent" format="string"/>

  </declare-styleable>
</resources>

Your styleable name being the Class name of your custom view.

Creating a View Class

For building a custom theme to expand upon your comment you can swap around themes rather than using attrs.xml

Change Current Theme At Runtime - Stackoverflow

edited Jan 10 '20 at 17:00

answered Jan 10 '20 at 16:32

C. Skjerdal

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Thank you for your reply! I'm not using a custom button, just a normal AppComatButton, with a custom background and textColor. However, since I want to have different themes for my app, I'm defining the colors as theme attributes and applying them to my button. Can I do it, or do I need to crate a custom Button that extends the AppComactButton? – Lucas P. Jan 10 '20 at 16:53
Off my head, I think you don't need the attrs.xml in that case then. Just have different groups of style themes other than "AppTheme" and swap that around. I've never tried to swap themes, though always wanted to, so I don't have code to confirm this is the correct method. – C. Skjerdal Jan 10 '20 at 16:58
1

Added a link in my answer that might help – C. Skjerdal Jan 10 '20 at 17:01

Using custom attributes in layout crashes app

2 Answers2