How to Fix Clojure Accessing Static Inner Class Builder Expecting Var But Mapped to Class Error During Build

What steps can I take to resolve the 'Expecting var but mapped to class' error when using a static inner class builder in Clojure?

def myBuilder = MyStaticInnerClass.builder()

When working with static inner classes in Clojure, developers may encounter an error stating 'Expecting var but mapped to class'. This issue usually arises due to improper handling of static inner classes while building instances. This guide will discuss the causes and solutions for this problem, allowing you to use static inner class builders seamlessly in your Clojure projects.

(import 'com.example.MyOuterClass$MyStaticInnerClass)
(def builder (MyStaticInnerClass/builder))
(def instance (.build builder))
(def instance-with-attribute (.setAttribute instance "value"))

Causes

• Improper usage of Java static inner classes in Clojure.
• Lack of appropriate imports for the inner class builder.
• Confusion between methods and types in macros.

Solutions

• Ensure you are using the correct syntax for instance creation.
• Verify that the static inner class is accessible from your Clojure namespace.
• Use the qualified name of the inner class while initializing the builder, for example: `MyOuterClass$MyStaticInnerClass/builder()`.

Mistake: Using the wrong namespace or not importing the class correctly.

Solution: Use explicit imports and ensure the inner class is referenced correctly.

Mistake: Not using the dollar sign ($) to reference the inner class correctly in Clojure.

Solution: Always remember to use the `$` syntax for static inner classes when accessing them.