Add Support for Final Fields

Author: jrosen081

Sources/Java2SwiftLib/JavaTranslator.swift

@@ -546,7 +546,7 @@ extension JavaTranslator {
     let fieldAttribute: AttributeSyntax = javaField.isStatic ? "@JavaStaticField" : "@JavaField";
     let swiftFieldName = javaField.getName().escapedSwiftName
     return """
-      \(fieldAttribute)
+      \(fieldAttribute)(isFinal: \(raw: javaField.isFinal))
       public var \(raw: swiftFieldName): \(raw: typeName)
       """
   }

Sources/JavaKit/Macros.swift

@@ -92,7 +92,7 @@ public macro JavaInterface(_ fullClassName: String, extends: (any AnyJavaObject.
 /// }
 /// ```
 @attached(accessor)
-public macro JavaField(_ javaFieldName: String? = nil) = #externalMacro(module: "JavaKitMacros", type: "JavaFieldMacro")
+public macro JavaField(_ javaFieldName: String? = nil, isFinal: Bool = false) = #externalMacro(module: "JavaKitMacros", type: "JavaFieldMacro")
 
 
 /// Attached macro that turns a Swift property into one that accesses a Java static field on the underlying Java object.
@@ -106,7 +106,7 @@ public macro JavaField(_ javaFieldName: String? = nil) = #externalMacro(module:
 /// }
 /// ```
 @attached(accessor)
-public macro JavaStaticField(_ javaFieldName: String? = nil) = #externalMacro(module: "JavaKitMacros", type: "JavaFieldMacro")
+public macro JavaStaticField(_ javaFieldName: String? = nil, isFinal: Bool = false) = #externalMacro(module: "JavaKitMacros", type: "JavaFieldMacro")
 
 /// Attached macro that turns a Swift method into one that wraps a Java method on the underlying Java object.
 ///

Sources/JavaKitMacros/JavaFieldMacro.swift

@@ -46,14 +46,31 @@ extension JavaFieldMacro: AccessorMacro {
         fieldNameAsWritten
       }
 
+    let createSetter =
+    if case .argumentList(let arguments) = node.arguments,
+       let wrapperIsBoolean = arguments.first(where: { $0.label?.text == "isFinal" })?.expression,
+        let booleanLiteral = wrapperIsBoolean.as(BooleanLiteralExprSyntax.self)
+    {
+      booleanLiteral.literal.text == "false" // Create the setter if we are not final
+    } else {
+      true
+    }
+
     let getter: AccessorDeclSyntax = """
       get { self[javaFieldName: \(literal: fieldName), fieldType: \(fieldType).self] }
       """
 
-    let setter: AccessorDeclSyntax = """
-      nonmutating set { self[javaFieldName: \(literal: fieldName), fieldType: \(fieldType).self] = newValue }
-      """
+    var accessors: [AccessorDeclSyntax] = [
+      getter
+    ]
+
+    if createSetter {
+      let setter: AccessorDeclSyntax = """
+        nonmutating set { self[javaFieldName: \(literal: fieldName), fieldType: \(fieldType).self] = newValue }
+        """
+      accessors.append(setter)
+    }
 
-    return [getter, setter]
+    return accessors
   }
 }

Sources/JavaKitReflection/Field+Utilities.swift

@@ -17,4 +17,9 @@ extension Field {
     public var isStatic: Bool {
       return (getModifiers() & 0x08) != 0
     }
+
+  /// Whether this is a 'final' field.
+  public var isFinal: Bool {
+    return (getModifiers() & 16) != 0
+  }
 }

Tests/Java2SwiftTests/Java2SwiftTests.swift

@@ -75,7 +75,7 @@ class Java2SwiftTests: XCTestCase {
                 }
         """,
         """
-          @JavaStaticField
+          @JavaStaticField(isFinal: true)
           public var APRIL: Month?
         """
       ])

Tests/JavaKitMacroTests/JavaClassMacroTests.swift

@@ -41,6 +41,9 @@ class JavaKitMacroTests: XCTestCase {
 
           @JavaField
           public var myField: Int64
+      
+          @JavaField(isFinal: true)
+          public var myFinalField: Int64
         }
       """,
       expandedSource: """
@@ -73,6 +76,11 @@ class JavaKitMacroTests: XCTestCase {
                   self[javaFieldName: "myField", fieldType: Int64.self] = newValue
               }
           }
+          public var myFinalField: Int64 {
+              get {
+                  self[javaFieldName: "myFinalField", fieldType: Int64.self]
+              }
+          }
       
             /// The full Java class name for this Swift type.
             public static var fullJavaClassName: String {