java/Object: add Object.toString() wrapper

src/Main.cxx

@@ -639,6 +639,7 @@ JNIEXPORT void JNICALL
 Java_org_musicpd_Bridge_run(JNIEnv *env, jclass, jobject _context, jobject _logListener)
 {
 	Java::Init(env);
+	Java::Object::Initialise(env);
 	Java::File::Initialise(env);
 	Environment::Initialise(env);
 

src/java/Object.cxx

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2010-2019 Max Kellermann <max.kellermann@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "Object.hxx"
+#include "Class.hxx"
+
+jmethodID Java::Object::toString_method;
+
+void
+Java::Object::Initialise(JNIEnv *env)
+{
+	assert(env != nullptr);
+
+	Class cls(env, "java/lang/Object");
+
+	toString_method = env->GetMethodID(cls, "toString",
+					   "()Ljava/lang/String;");
+	assert(toString_method != nullptr);
+}

src/java/Object.hxx

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2018 Max Kellermann <max.kellermann@gmail.com>
+ * Copyright 2010-2019 Max Kellermann <max.kellermann@gmail.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -34,6 +34,8 @@
 
 #include <jni.h>
 
+#include <assert.h>
+
 namespace Java {
 	/**
 	 * Wrapper for a local "jobject" reference.
@@ -51,6 +53,24 @@ namespace Java {
 		GlobalObject(JNIEnv *env, jobject obj) noexcept
 			:GlobalRef<jobject>(env, obj) {}
 	};
+
+	/**
+	 * Utilities for java.net.Object.
+	 */
+	class Object {
+		static jmethodID toString_method;
+
+	public:
+		static void Initialise(JNIEnv *env);
+
+		static jstring toString(JNIEnv *env, jobject o) {
+			assert(env != nullptr);
+			assert(o != nullptr);
+			assert(toString_method != nullptr);
+
+			return (jstring)env->CallObjectMethod(o, toString_method);
+		}
+	};
 }
 
 #endif

src/java/meson.build

@@ -2,6 +2,7 @@ java = static_library(
   'java',
   'Global.cxx',
   'File.cxx',
+  'Object.cxx',
   'String.cxx',
   include_directories: inc,
   dependencies: [