java/Exception: add RethrowException()

src/java/Exception.cxx

+/*
+ * 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 "Exception.hxx"
+#include "Object.hxx"
+#include "String.hxx"
+
+Java::Exception::Exception(JNIEnv *env, jthrowable e) noexcept
+	:std::runtime_error(Java::String(env, Object::toString(env, e)).ToString())
+{
+}
+
+void
+Java::RethrowException(JNIEnv *env)
+{
+	jthrowable exception = env->ExceptionOccurred();
+	if (exception == nullptr)
+		return;
+
+	LocalRef<jthrowable> ref(env, exception);
+
+	env->ExceptionClear();
+	throw Exception(env, exception);
+}

src/java/Exception.hxx

 /*
- * 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
@@ -30,9 +30,22 @@
 #ifndef JAVA_EXCEPTION_HXX
 #define JAVA_EXCEPTION_HXX
 
+#include <stdexcept>
+
 #include <jni.h>
 
 namespace Java {
+	class Exception : public std::runtime_error {
+	public:
+		explicit Exception(JNIEnv *env, jthrowable e) noexcept;
+	};
+
+	/**
+	 * Check if a Java exception has occurred, and if yes, convert
+	 * it to a C++ #Exception and throw that.
+	 */
+	void RethrowException(JNIEnv *env);
+
 	/**
 	 * Check if an exception has occurred, and discard it.
 	 *

src/java/meson.build

 java = static_library(
   'java',
   'Global.cxx',
+  'Exception.cxx',
   'File.cxx',
   'Object.cxx',
   'String.cxx',