Introduce the @JavaStaticMethod and use it for calling static Java methods

The use of the `@JavaMethod` macro within an extension of `JavaClass` to
represent static Java methods on that class didn't quite work, because
JavaClass is itself an AnyJavaObject with its own methods. Introduce
a `@JavaStaticMethod` macro that will be used for this purpose, and
have it call through a separate API (`dynamicJavaStaticMethodCall`).

Thank you to Lokesh for reporting this bug!

Author: DougGregor

Sources/Java2Swift/JavaTranslator.swift

@@ -416,8 +416,9 @@ extension JavaTranslator {
 
     let throwsStr = javaMethod.throwsCheckedException ? "throws" : ""
 
+    let methodAttribute: AttributeSyntax = javaMethod.isStatic ? "@JavaStaticMethod" : "@JavaMethod";
     return """
-      @JavaMethod
+      \(methodAttribute)
       public func \(raw: javaMethod.getName())\(raw: genericParameterClause)(\(raw: parametersStr))\(raw: throwsStr)\(raw: resultTypeStr)\(raw: whereClause)
       """
   }

Sources/JavaKit/JavaObject+MethodCalls.swift

@@ -301,9 +301,10 @@ extension AnyJavaObject {
 extension JavaClass {
   /// Call a Java static method with the given name and arguments, which must be
   /// of the correct type, that produces the given result type.
-  public func dynamicJavaMethodCall<each Param: JavaValue, Result: JavaValue>(
+  public func dynamicJavaStaticMethodCall<each Param: JavaValue, Result: JavaValue>(
     methodName: String,
-    args: repeat each Param
+    arguments: repeat each Param,
+    resultType: Result.Type
   ) throws -> Result {
     let thisClass = javaThis
     let environment = javaEnvironment
@@ -325,7 +326,7 @@ extension JavaClass {
 
     // Retrieve the method that performs this call, then
     let jniMethod = Result.jniStaticMethodCall(in: environment)
-    let jniArgs = getJValues(repeat each args, in: environment)
+    let jniArgs = getJValues(repeat each arguments, in: environment)
     let jniResult = try environment.translatingJNIExceptions {
       jniMethod(environment, thisClass, methodID, jniArgs)
     }
@@ -335,9 +336,9 @@ extension JavaClass {
 
   /// Call a Java static method with the given name and arguments, which must be
   /// of the correct type, that produces the given result type.
-  public func dynamicJavaMethodCall<each Param: JavaValue>(
+  public func dynamicJavaStaticMethodCall<each Param: JavaValue>(
     methodName: String,
-    args: repeat each Param
+    arguments: repeat each Param
   ) throws {
     let thisClass = javaThis
     let environment = javaEnvironment
@@ -359,7 +360,7 @@ extension JavaClass {
 
     // Retrieve the method that performs this call, then
     let jniMethod = environment.interface.CallStaticVoidMethodA
-    let jniArgs = getJValues(repeat each args, in: environment)
+    let jniArgs = getJValues(repeat each arguments, in: environment)
     try environment.translatingJNIExceptions {
       jniMethod!(environment, thisClass, methodID, jniArgs)
     }

Sources/JavaKit/Macros.swift

@@ -95,7 +95,7 @@ public macro JavaField(_ javaFieldName: String? = nil) = #externalMacro(module:
 
 /// Attached macro that turns a Swift method into one that wraps a Java method on the underlying Java object.
 ///
-/// The macro must be used within either a AnyJavaObject-conforming type or a specific JavaClass instance.
+/// The macro must be used in an AnyJavaObject-conforming type.
 ///
 /// ```swift
 /// @JavaMethod
@@ -115,6 +115,18 @@ public macro JavaField(_ javaFieldName: String? = nil) = #externalMacro(module:
 @attached(body)
 public macro JavaMethod() = #externalMacro(module: "JavaKitMacros", type: "JavaMethodMacro")
 
+/// Attached macro that turns a Swift method on JavaClass into one that wraps
+/// a Java static method on the underlying Java class object.
+///
+/// The macro must be used within a specific JavaClass instance.
+///
+/// ```swift
+/// @JavaMethod
+/// func sayHelloBack(_ i: Int32) -> Double
+/// ```
+@attached(body)
+public macro JavaStaticMethod() = #externalMacro(module: "JavaKitMacros", type: "JavaMethodMacro")
+
 /// Macro that exposes the given Swift method as a native method in Java.
 ///
 /// The macro must be used within a struct type marked with `@JavaClass`, and there

Sources/JavaKitMacros/JavaMethodMacro.swift

@@ -34,6 +34,7 @@ extension JavaMethodMacro: BodyMacro {
       fatalError("not a function")
     }
 
+    let isStatic = node.attributeName.trimmedDescription == "JavaStaticMethod"
     let funcName = funcDecl.name.text
     let params = funcDecl.signature.parameterClause.parameters
     let resultType: String =
@@ -54,7 +55,7 @@ extension JavaMethodMacro: BodyMacro {
       ? "try" : "try!"
 
     return [
-      "return \(raw: tryKeyword) dynamicJavaMethodCall(methodName: \(literal: funcName)\(raw: parametersAsArgs)\(raw: resultType))"
+      "return \(raw: tryKeyword) dynamicJava\(raw: isStatic ? "Static" : "")MethodCall(methodName: \(literal: funcName)\(raw: parametersAsArgs)\(raw: resultType))"
     ]
   }
 

Sources/JavaKitNetwork/generated/URLConnection.swift

@@ -146,7 +146,7 @@ extension JavaClass<URLConnection> {
   @JavaMethod
   public func setDefaultAllowUserInteraction(_ arg0: Bool)
 
-  @JavaMethod
+  @JavaStaticMethod
   public func getDefaultAllowUserInteraction() -> Bool
 
   @JavaMethod

Tests/JavaKitTests/BasicRuntimeTests.swift

@@ -66,4 +66,14 @@ struct BasicRuntimeTests {
       #expect(String(describing: error) == "no protocol: bad url")
     }
   }
+
+  @Test("Static methods")
+  func staticMethods() {
+    let urlConnectionClass = JavaClass<URLConnection>(
+      javaThis: URLConnection.getJNIClass(in: jvm.environment)!,
+      environment: jvm.environment
+    )
+
+    #expect(urlConnectionClass.getDefaultAllowUserInteraction() == false)
+  }
 }