Blankj/AndroidUtilCode · error · Exception

ApiExtension's apiUtilsClass is empty.

Error message

ApiExtension's apiUtilsClass is empty.

What it means

ApiPlugin.onScanStarted() reads ext.apiUtilsClass (ApiExtension default "com.blankj.utilcode.util.ApiUtils"). If, after trim(), the value is empty, it throws Exception. The plugin needs the fully-qualified ApiUtils class name to know which class to inject the registered impls into during transform.

Source

Thrown at plugin/api-gradle-plugin/src/main/java/com/blankj/api/ApiPlugin.groovy:30

class ApiPlugin extends BaseTransformPlugin<ApiExtension> {

    String apiUtilsClass
    File jsonFile
    File apiUtilsTransformFile
    Map<String, ApiInfo> apiImplMap = [:]
    List<String> apiClasses = []

    @Override
    String getPluginName() {
        return Config.EXT_NAME
    }

    @Override
    void onScanStarted() {
        apiUtilsClass = ext.apiUtilsClass
        if (apiUtilsClass.trim().equals("")) {
            throw new Exception("ApiExtension's apiUtilsClass is empty.")
        }

        jsonFile = new File(mProject.projectDir.getAbsolutePath(), "__api__.json")
        FileUtils.write(jsonFile, "{}")
    }

    @Override
    boolean isIgnoreScan(JarInput input) {
        def jarName = input.name
        if (jarName.contains("utilcode")) {
            return false
        }

        if (ext.onlyScanLibRegex != null && ext.onlyScanLibRegex.trim().length() > 0) {
            return !Pattern.matches(ext.onlyScanLibRegex, jarName)
        }

        if (ext.jumpScanLibRegex != null && ext.jumpScanLibRegex.trim().length() > 0) {

View on GitHub (pinned to 7b4caf9e54)

Solutions

1. Set apiUtilsClass to the fully-qualified name of your ApiUtils class, e.g. api { apiUtilsClass 'com.blankj.utilcode.util.ApiUtils' }.
2. If you use AndroidUtilCode's built-in ApiUtils, remove the apiUtilsClass override so the default applies.
3. Make sure no build logic assigns an empty/whitespace string to ext.apiUtilsClass.

Example fix

// before
api {
    apiUtilsClass ""   // -> "ApiExtension's apiUtilsClass is empty."
}

// after
api {
    apiUtilsClass "com.blankj.utilcode.util.ApiUtils"
}
// or omit the api{} block entirely to use the default

afterEvaluate {
    def extApi = project.extensions.findByName('api')
    if (extApi == null || !extApi.apiUtilsClass?.trim()) {
        throw new GradleException("api { apiUtilsClass '...' } must be set and non-blank.")
    }
}

When it happens

Trigger: Configuring the api{} DSL with apiUtilsClass set to an empty string or whitespace, e.g. api { apiUtilsClass "" }; or assigning a property that resolves to a blank value.

Common situations: Pointing the api extension at a custom ApiUtils class but leaving the path blank; a typo or cleared property; copy-pasting a config snippet that omitted the value.

Related errors

• <" + className + "> and <" + apiInfo.implApiClass + "> impl
• u should impl these apis: " + noImplApis + "\n u can check i
• No ApiUtils of ${apiUtilsClass} in $mProject.
• BusExtension's busUtilsClass is empty.
• These buses is not right: " + wrongBus + "\n u can check it

AI-assisted analysis of Blankj/AndroidUtilCode@7b4caf9e54 (2026-08-14). Data as JSON: /api/errors/cbe6676d9b6fa98d. Report an issue: GitHub.