allows static method calls on JNIObject (#14)

* allow calling static methods on JNIObjects

* reindent

* deprecate init with explicit className

* implement private classInstances cache

* use static getter for classinstances

Author: michaelknoch

Sources/JNI/JNIObjects.swift

@@ -1,23 +1,42 @@
 import CJNI
+import Dispatch
 
 /// Designed to simplify calling a constructor and methods on a JavaClass
 /// Subclass this and add the methods appropriate to the object you are constructing.
 open class JNIObject {
-    public let javaClass: JavaClass
+    open class var className: String {
+        return "java.lang.object"
+    }
+
+    private static var classInstances = [String: JavaClass]()
+
+    public static var javaClass: JavaClass {
+        return DispatchQueue.main.sync {
+            if let classInstance = classInstances[className] {
+                return classInstance
+            }
+
+            let javaClassLocalRef = try! jni.FindClass(name: className.replacingFullstopsWithSlashes())
+            try! checkAndThrowOnJNIError()
+            let classInstance = jni.NewGlobalRef(javaClassLocalRef)!
+            classInstances[className] = classInstance
+
+            return classInstance
+        }
+    }
+
     public let instance: JavaObject
 
     required public init(_ instance: JavaObject) throws {
         guard let globalInstanceRef = jni.NewGlobalRef(instance) else {
             throw Error.couldntCreateGlobalRef
         }
 
-        let javaClassLocalRef = try jni.GetObjectClass(obj: instance)
-        let javaClass = jni.NewGlobalRef(javaClassLocalRef)
         try checkAndThrowOnJNIError()
-        self.javaClass = javaClass!
         self.instance = globalInstanceRef
     }
 
+    @available(*, deprecated, message: "Override Self.className instead and use the initializers that don't take className as an argument")
     convenience public init(_ className: String, arguments: [JavaParameterConvertible] = []) throws {
         let className = className.replacingFullstopsWithSlashes()
         let javaClassLocalRef = try jni.FindClass(name: className)
@@ -29,22 +48,39 @@ open class JNIObject {
         try self.init(instanceLocalRef)
     }
 
+    convenience public init(arguments: JavaParameterConvertible...) throws {
+        guard let instanceLocalRef = try jni.callConstructor(on: type(of: self).javaClass, arguments: arguments) else {
+            throw Error.couldntCallConstructor
+        }
+
+        try self.init(instanceLocalRef)
+    }
+
     deinit {
         jni.DeleteGlobalRef(instance)
-        jni.DeleteGlobalRef(javaClass)
     }
 
     public func call(methodName: String, arguments: [JavaParameterConvertible] = []) throws {
         try jni.call(methodName, on: self.instance, arguments: arguments)
     }
 
-    public func call<T: JavaInitializableFromMethod & JavaParameterConvertible>(methodName: String, arguments: [JavaParameterConvertible] = []) throws -> T {
+    public func call<T: JavaInitializableFromMethod & JavaParameterConvertible>(
+        methodName: String,
+        arguments: [JavaParameterConvertible] = []
+    ) throws -> T {
         return try jni.call(methodName, on: self.instance, arguments: arguments)
     }
 
-    public func callStatic(methodName: String, arguments: [JavaParameterConvertible] = []) throws {
+    public static func callStatic(methodName: String, arguments: [JavaParameterConvertible] = []) throws {
         try jni.callStatic(methodName, on: self.javaClass, arguments: arguments)
     }
+
+    public static func callStatic<T: JavaInitializableFromMethod & JavaParameterConvertible>(
+        methodName: String,
+        arguments: [JavaParameterConvertible] = []
+    ) throws -> T {
+        return try jni.callStatic(methodName, on: self.javaClass, arguments: arguments)
+    }
 }
 
 extension JNIObject {
@@ -55,7 +91,10 @@ extension JNIObject {
 }
 
 extension JNI {
-    func callConstructor(on targetClass: JavaClass, arguments: [JavaParameterConvertible] = []) throws -> JavaObject? {
+    func callConstructor(
+        on targetClass: JavaClass,
+        arguments: [JavaParameterConvertible] = []
+    ) throws -> JavaObject? {
         let methodID = _env.pointee.pointee.GetMethodID(_env, targetClass, "<init>", arguments.methodSignature(returnType: nil))
         try checkAndThrowOnJNIError()
 
@@ -64,19 +103,19 @@ extension JNI {
 }
 
 public extension JNI {
-	public func NewObject(targetClass: JavaClass, _ methodID: JavaMethodID, _ args: [JavaParameter]) throws -> JavaObject? {
-	    let env = self._env
+    func NewObject(targetClass: JavaClass, _ methodID: JavaMethodID, _ args: [JavaParameter]) throws -> JavaObject? {
+        let env = self._env
         var mutableArgs = args
         let newObject = env.pointee.pointee.NewObject(env, targetClass, methodID, &mutableArgs)
         try checkAndThrowOnJNIError()
 
         return newObject
-	}
+    }
 
-	public func GetObjectClass(obj: JavaObject) throws -> JavaClass {
-	    let env = self._env
+    func GetObjectClass(obj: JavaObject) throws -> JavaClass {
+        let env = self._env
         let result = env.pointee.pointee.GetObjectClass(env, obj)
         try checkAndThrowOnJNIError()
         return result!
-	}
+    }
 }