When the Invocation Interface is being used (that is, when a C++ program calls into Java code), the getContext() method of the JavaVirtualMachine class is used to obtain an appropriate JavaContext object. More...

#include <JavaContext.h++>

Public Member Functions
	JavaContext (JNIEnv *env)
	Construct a new JavaContext for the given JNI environment pointer. More...

	~JavaContext ()
	Destructor. More...

jclass	findClass (const String &name)
	Look up a class by name. More...

jclass	defineClass (const String &name, const byte_t *buf, size_t length)
	Define a Java class from a buffer of raw bytecode. More...

jmethodID	findMethod (jclass clazz, const String &signature)
	Look up a method or constructor by signature. More...

jobject	createObject (jclass clazz, jmethodID constructor,...)
	Instantiate a new Java object. More...

jobject	createObjectVA (jclass clazz, jmethodID constructor, va_list args)
	Instantiate a new Java object. More...

void	callVoidMethod (jobject object, jmethodID method,...)
	Call a Java method that returns void. More...

jobject	callObjectMethod (jobject object, jmethodID method,...)
	Call a Java method that returns a Java Object. More...

String	callStringMethod (jobject object, jmethodID method,...)
	Call a Java method that returns a java.lang.String. More...

bool	callBooleanMethod (jobject object, jmethodID method,...)
	Call a Java method that returns a boolean. More...

byte_t	callByteMethod (jobject object, jmethodID method,...)
	Call a Java method that returns a byte. More...

char16_t	callCharMethod (jobject object, jmethodID method,...)
	Call a Java method that returns a char. More...

int16_t	callShortMethod (jobject object, jmethodID method,...)
	Call a Java method that returns a short. More...

int32_t	callIntMethod (jobject object, jmethodID method,...)
	Call a Java method that returns an int. More...

int64_t	callLongMethod (jobject object, jmethodID method,...)
	Call a Java method that returns a long. More...

float	callFloatMethod (jobject object, jmethodID method,...)
	Call a Java method that returns a float. More...

double	callDoubleMethod (jobject object, jmethodID method,...)
	Call a Java method that returns a double. More...

void	callNonvirtualVoidMethod (jobject object, jclass clazz, jmethodID method,...)
	Call a non-virtual Java method that returns void. More...

jobject	callNonvirtualObjectMethod (jobject object, jclass clazz, jmethodID method,...)
	Call a non-virtual Java method that returns a Java object. More...

bool	callNonvirtualBooleanMethod (jobject object, jclass clazz, jmethodID method,...)
	Call a non-virtual Java method that returns a boolean. More...

byte_t	callNonvirtualByteMethod (jobject object, jclass clazz, jmethodID method,...)
	Call a non-virtual Java method that returns a byte. More...

char16_t	callNonvirtualCharMethod (jobject object, jclass clazz, jmethodID method,...)
	Call a non-virtual Java method that returns a char. More...

int16_t	callNonvirtualShortMethod (jobject object, jclass clazz, jmethodID method,...)
	Call a non-virtual Java method that returns a short. More...

int32_t	callNonvirtualIntMethod (jobject object, jclass clazz, jmethodID method,...)
	Call a non-virtual Java method that returns an int. More...

int64_t	callNonvirtualLongMethod (jobject object, jclass clazz, jmethodID method,...)
	Call a non-virtual Java method that returns a long. More...

float	callNonvirtualFloatMethod (jobject object, jclass clazz, jmethodID method,...)
	Call a non-virtual Java method that returns a float. More...

double	callNonvirtualDoubleMethod (jobject object, jclass clazz, jmethodID method,...)
	Call a non-virtual Java method that returns a double. More...

void	callStaticVoidMethod (jclass clazz, jmethodID method,...)
	Call a static Java method that returns void. More...

jobject	callStaticObjectMethod (jclass clazz, jmethodID method,...)
	Call a static Java method that returns a Java Object. More...

String	callStaticStringMethod (jclass clazz, jmethodID method,...)
	Call a static Java method that returns a java.lang.String. More...

bool	callStaticBooleanMethod (jclass clazz, jmethodID method,...)
	Call a static Java method that returns a boolean. More...

byte_t	callStaticByteMethod (jclass clazz, jmethodID method,...)
	Call a static Java method that returns a byte. More...

char16_t	callStaticCharMethod (jclass clazz, jmethodID method,...)
	Call a static Java method that returns a char. More...

int16_t	callStaticShortMethod (jclass clazz, jmethodID method,...)
	Call a static Java method that returns a short. More...

int32_t	callStaticIntMethod (jclass clazz, jmethodID method,...)
	Call a static Java method that returns an int. More...

int64_t	callStaticLongMethod (jclass clazz, jmethodID method,...)
	Call a static Java method that returns a long. More...

float	callStaticFloatMethod (jclass clazz, jmethodID method,...)
	Call a static Java method that returns a float. More...

double	callStaticDoubleMethod (jclass clazz, jmethodID method,...)
	Call a static Java method that returns a double. More...

bool	checkException (bool verbose=false)
	Determine if a Java exception has been thrown in the current thread. More...

void	clearException ()
	Clear any pending Java exception that is currently being thrown in the current thread. More...

jthrowable	getException ()
	Get the pending Java exception, if one is currently being thrown in the current thread. More...

bool	throwException (jclass exception, const String &message)
	Throw a Java exception. More...

jfieldID	findField (jclass clazz, const String &signature)
	Look up a field by signature. More...

jobject	getObjectField (jobject object, jfieldID field)
	Get the value of an Object field in an Object. More...

bool	getBooleanField (jobject object, jfieldID field)
	Get the value of an boolean field in an Object. More...

byte_t	getByteField (jobject object, jfieldID field)
	Get the value of a byte field in an Object. More...

char16_t	getCharField (jobject object, jfieldID field)
	Get the value of a char field in an Object. More...

int16_t	getShortField (jobject object, jfieldID field)
	Get the value of a short field in an Object. More...

int32_t	getIntField (jobject object, jfieldID field)
	Get the value of an int field in an Object. More...

int64_t	getLongField (jobject object, jfieldID field)
	Get the value of a long field in an Object. More...

float	getFloatField (jobject object, jfieldID field)
	Get the value of a float field in an Object. More...

double	getDoubleField (jobject object, jfieldID field)
	Get the value of a double field in an Object. More...

String	getStringField (jobject object, jfieldID field)
	Get the value of a java.lang.String field in an Object. More...

jobject	getStaticObjectField (jclass clazz, jfieldID field)
	Get the value of a static Object field in a class. More...

bool	getStaticBooleanField (jclass clazz, jfieldID field)
	Get the value of a static boolean field in a class. More...

byte_t	getStaticByteField (jclass clazz, jfieldID field)
	Get the value of a static byte field in a class. More...

char16_t	getStaticCharField (jclass clazz, jfieldID field)
	Get the value of a static char field in a class. More...

int16_t	getStaticShortField (jclass clazz, jfieldID field)
	Get the value of a static short field in a class. More...

int32_t	getStaticIntField (jclass clazz, jfieldID field)
	Get the value of a static int field in a class. More...

int64_t	getStaticLongField (jclass clazz, jfieldID field)
	Get the value of a static long field in a class. More...

float	getStaticFloatField (jclass clazz, jfieldID field)
	Get the value of a static float field in a class. More...

double	getStaticDoubleField (jclass clazz, jfieldID field)
	Get the value of a static double field in a class. More...

String	getStaticStringField (jclass clazz, jfieldID field)
	Get the value of a static String field in a class. More...

void	setObjectField (jobject object, jfieldID field, jobject value)
	Set the value of an Object field in an object. More...

void	setBooleanField (jobject object, jfieldID field, bool value)
	Set the value of a boolean field in an object. More...

void	setByteField (jobject object, jfieldID field, byte_t value)
	Set the value of a byte field in an object. More...

void	setCharField (jobject object, jfieldID field, char16_t value)
	Set the value of a char field in an object. More...

void	setShortField (jobject object, jfieldID field, int16_t value)
	Set the value of a short field in an object. More...

void	setIntField (jobject object, jfieldID field, int32_t value)
	Set the value of an int field in an object. More...

void	setLongField (jobject object, jfieldID field, int64_t value)
	Set the value of a long field in an object. More...

void	setFloatField (jobject object, jfieldID field, float value)
	Set the value of a float field in an object. More...

void	setDoubleField (jobject object, jfieldID field, double value)
	Set the value of a double field in an object. More...

void	setStringField (jobject object, jfieldID field, const String &value)
	Set the value of a java.lang.String field in an object. More...

void	setStaticObjectField (jclass clazz, jfieldID field, jobject value)
	Set the value of a static Object field in a class. More...

void	setStaticBooleanField (jclass clazz, jfieldID field, bool value)
	Set the value of a static boolean field in a class. More...

void	setStaticByteField (jclass clazz, jfieldID field, byte_t value)
	Set the value of a static byte field in a class. More...

void	setStaticCharField (jclass clazz, jfieldID field, char16_t value)
	Set the value of a static char field in a class. More...

void	setStaticShortField (jclass clazz, jfieldID field, int16_t value)
	Set the value of a static short field in a class. More...

void	setStaticIntField (jclass clazz, jfieldID field, int32_t value)
	Set the value of a static int field in a class. More...

void	setStaticLongField (jclass clazz, jfieldID field, int64_t value)
	Set the value of a static long field in a class. More...

void	setStaticFloatField (jclass clazz, jfieldID field, float value)
	Set the value of a static float field in a class. More...

void	setStaticDoubleField (jclass clazz, jfieldID field, double value)
	Set the value of a static double field in a class. More...

jbyteArray	createByteArray (uint_t length)
	Create a Java byte array. More...

void	setObjectArrayElement (jobjectArray array, uint_t index, jobject value)
	Set an element of a Java object array. More...

jobject	getObjectArrayElement (jobjectArray array, uint_t index)
	Get an element of a Java object array. More...

uint_t	getArrayLength (jarray array)
	Get the length of a Java array. More...

jobject	createDirectByteBuffer (byte_t *buf, size_t size)
	Create a new Java DirectByteBuffer. More...

void *	getDirectBufferRegion (jobject buf, uint64_t &size)
	Get a pointer to and the size of the memory region occupied by a Java DirectBuffer. More...

jobject	createLocalRef (jobject object)
	Create a local reference to a Java object. More...

void	deleteLocalRef (jobject ref)
	Delete a local reference. More...

void	ensureLocalCapacity (uint_t capacity)
	Reserve space for local references. More...

jobject	createGlobalRef (jobject object)
	Create a global reference to a Java object. More...

void	deleteGlobalRef (jobject ref)
	Delete a local reference. More...

String	decodeString (jstring str)
	Decode a java.lang.String into a String. More...

jstring	encodeString (const String &str)
	Encode a String into a java.lang.String. More...

uint_t	getStringLength (jstring str)
	Get the length of a Java string. More...

void *	getArrayData (jarray array, uint_t &length, bool *isCopy=NULL)
	Obtain a pointer to the body of a primitive Java array. More...

void	releaseArrayData (jarray array, void *data)
	Release the buffer returned by getArrayData(). More...

jbyteArray	createByteArray (const byte_t *data, size_t length)
	Create a Java byte array. More...

jarray	createObjectArray (jclass type, uint_t length, jobject initialValue=NULL)
	Create a Java object array. More...

bool	isSameObject (jobject object1, jobject object2)
	Test two Java object references for equality. More...

bool	isInstanceOf (jobject object, jclass clazz)
	Test if a Java object is an instance of an interface or another class. More...

bool	isAssignableFrom (jclass clazz1, jclass clazz2)
	Test if an object of a class or interface can be safely cast to a class or interface of another class. More...

jclass	getClassForObject (jobject object)
	Get the class for a Java object. More...

jclass	getSuperclass (jclass clazz)
	Get the superclass for a Java class. More...

void	enterMonitor (jobject object)
	Enter the monitor associated with a Java object. More...

void	exitMonitor (jobject object)
	Exit the monitor associated with a Java object. More...

void	registerNativeMethods (jclass clazz, const JavaNativeMethod methods[])
	Register native methods for a Java class. More...

void	unregisterNativeMethods (jclass clazz)
	Unregister all native methods for a Java class. More...

void	pushLocalFrame (uint_t capacity=8)
	Create a new local reference frame. More...

void	popLocalFrame ()
	Destroy the topmost local reference frame. More...

bool	isVerbose () const
	Determine if verbose mode is enabled for this context. More...

Static Public Member Functions
static String	encodeType (const String &type)
	Encode a datatype into a JNI datatype descriptor. More...

static bool	parseSignature (const String &signature, String &method, String &descriptor, bool &isStatic)
	Parse a method signature into a method name, a JNI method descriptor, and a static flag. More...

Friends
class	JavaVirtualMachine

Detailed Description

When the Invocation Interface is being used (that is, when a C++ program calls into Java code), the getContext() method of the JavaVirtualMachine class is used to obtain an appropriate JavaContext object.

In C++ code that implements a Java native method, on the other hand, a JavaContext instance must be explicitly constructed from the JNIEnv pointer that was passed into the native function.

This is a lightweight object that should typically be stack-allocated, and may be passed and copied by value.

Author: Mark Lindner

Constructor & Destructor Documentation

◆ JavaContext()

JavaContext ( JNIEnv * env )

Construct a new JavaContext for the given JNI environment pointer.

Parameters

env	The JNI environment pointer.

◆ ~JavaContext()

~JavaContext ( )

Destructor.

Member Function Documentation

◆ callBooleanMethod()

bool callBooleanMethod	(	jobject	object,
		jmethodID	method,
			...
	)

Call a Java method that returns a boolean.

Parameters

object	The object instance.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callByteMethod()

byte_t callByteMethod	(	jobject	object,
		jmethodID	method,
			...
	)

Call a Java method that returns a byte.

Parameters

object	The object instance.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callCharMethod()

char16_t callCharMethod	(	jobject	object,
		jmethodID	method,
			...
	)

Call a Java method that returns a char.

Parameters

object	The object instance.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callDoubleMethod()

double callDoubleMethod	(	jobject	object,
		jmethodID	method,
			...
	)

Call a Java method that returns a double.

Parameters

object	The object instance.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callFloatMethod()

float callFloatMethod	(	jobject	object,
		jmethodID	method,
			...
	)

Call a Java method that returns a float.

Parameters

object	The object instance.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callIntMethod()

int32_t callIntMethod	(	jobject	object,
		jmethodID	method,
			...
	)

Call a Java method that returns an int.

Parameters

object	The object instance.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callLongMethod()

int64_t callLongMethod	(	jobject	object,
		jmethodID	method,
			...
	)

Call a Java method that returns a long.

Parameters

object	The object instance.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callNonvirtualBooleanMethod()

bool callNonvirtualBooleanMethod	(	jobject	object,
		jclass	clazz,
		jmethodID	method,
			...
	)

Call a non-virtual Java method that returns a boolean.

Parameters

object	The object instance.
clazz	The method's defining class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callNonvirtualByteMethod()

byte_t callNonvirtualByteMethod	(	jobject	object,
		jclass	clazz,
		jmethodID	method,
			...
	)

Call a non-virtual Java method that returns a byte.

Parameters

object	The object instance.
clazz	The method's defining class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callNonvirtualCharMethod()

char16_t callNonvirtualCharMethod	(	jobject	object,
		jclass	clazz,
		jmethodID	method,
			...
	)

Call a non-virtual Java method that returns a char.

Parameters

object	The object instance.
clazz	The method's defining class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callNonvirtualDoubleMethod()

double callNonvirtualDoubleMethod	(	jobject	object,
		jclass	clazz,
		jmethodID	method,
			...
	)

Call a non-virtual Java method that returns a double.

Parameters

object	The object instance.
clazz	The method's defining class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callNonvirtualFloatMethod()

float callNonvirtualFloatMethod	(	jobject	object,
		jclass	clazz,
		jmethodID	method,
			...
	)

Call a non-virtual Java method that returns a float.

Parameters

object	The object instance.
clazz	The method's defining class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callNonvirtualIntMethod()

int32_t callNonvirtualIntMethod	(	jobject	object,
		jclass	clazz,
		jmethodID	method,
			...
	)

Call a non-virtual Java method that returns an int.

Parameters

object	The object instance.
clazz	The method's defining class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callNonvirtualLongMethod()

int64_t callNonvirtualLongMethod	(	jobject	object,
		jclass	clazz,
		jmethodID	method,
			...
	)

Call a non-virtual Java method that returns a long.

Parameters

object	The object instance.
clazz	The method's defining class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callNonvirtualObjectMethod()

jobject callNonvirtualObjectMethod	(	jobject	object,
		jclass	clazz,
		jmethodID	method,
			...
	)

Call a non-virtual Java method that returns a Java object.

Parameters

object	The object instance.
clazz	The method's defining class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callNonvirtualShortMethod()

int16_t callNonvirtualShortMethod	(	jobject	object,
		jclass	clazz,
		jmethodID	method,
			...
	)

Call a non-virtual Java method that returns a short.

Parameters

object	The object instance.
clazz	The method's defining class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callNonvirtualVoidMethod()

void callNonvirtualVoidMethod	(	jobject	object,
		jclass	clazz,
		jmethodID	method,
			...
	)

Call a non-virtual Java method that returns void.

Parameters

object	The object instance.
clazz	The method's defining class.
method	The method to call.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callObjectMethod()

jobject callObjectMethod	(	jobject	object,
		jmethodID	method,
			...
	)

Call a Java method that returns a Java Object.

Parameters

object	The object instance.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callShortMethod()

int16_t callShortMethod	(	jobject	object,
		jmethodID	method,
			...
	)

Call a Java method that returns a short.

Parameters

object	The object instance.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callStaticBooleanMethod()

bool callStaticBooleanMethod	(	jclass	clazz,
		jmethodID	method,
			...
	)

Call a static Java method that returns a boolean.

Parameters

clazz	The Java class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callStaticByteMethod()

byte_t callStaticByteMethod	(	jclass	clazz,
		jmethodID	method,
			...
	)

Call a static Java method that returns a byte.

Parameters

clazz	The Java class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callStaticCharMethod()

char16_t callStaticCharMethod	(	jclass	clazz,
		jmethodID	method,
			...
	)

Call a static Java method that returns a char.

Parameters

clazz	The Java class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callStaticDoubleMethod()

double callStaticDoubleMethod	(	jclass	clazz,
		jmethodID	method,
			...
	)

Call a static Java method that returns a double.

Parameters

clazz	The Java class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callStaticFloatMethod()

float callStaticFloatMethod	(	jclass	clazz,
		jmethodID	method,
			...
	)

Call a static Java method that returns a float.

Parameters

clazz	The Java class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callStaticIntMethod()

int32_t callStaticIntMethod	(	jclass	clazz,
		jmethodID	method,
			...
	)

Call a static Java method that returns an int.

Parameters

clazz	The Java class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callStaticLongMethod()

int64_t callStaticLongMethod	(	jclass	clazz,
		jmethodID	method,
			...
	)

Call a static Java method that returns a long.

Parameters

clazz	The Java class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callStaticObjectMethod()

jobject callStaticObjectMethod	(	jclass	clazz,
		jmethodID	method,
			...
	)

Call a static Java method that returns a Java Object.

Parameters

clazz	The Java class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callStaticShortMethod()

int16_t callStaticShortMethod	(	jclass	clazz,
		jmethodID	method,
			...
	)

Call a static Java method that returns a short.

Parameters

clazz	The Java class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callStaticStringMethod()

String callStaticStringMethod	(	jclass	clazz,
		jmethodID	method,
			...
	)

Call a static Java method that returns a java.lang.String.

Parameters

clazz	The Java class.
method	The method to call.

Returns: The method's return value, as a String.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callStaticVoidMethod()

void callStaticVoidMethod	(	jclass	clazz,
		jmethodID	method,
			...
	)

Call a static Java method that returns void.

Parameters

clazz	The Java class.
method	The method to call.

Returns: The method's return value.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callStringMethod()

String callStringMethod	(	jobject	object,
		jmethodID	method,
			...
	)

Call a Java method that returns a java.lang.String.

Parameters

object	The object instance.
method	The method to call.

Returns: The method's return value, encoded as a String.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ callVoidMethod()

void callVoidMethod	(	jobject	object,
		jmethodID	method,
			...
	)

Call a Java method that returns void.

Parameters

object	The object instance.
method	The method to call.

Exceptions

JavaException If the called method throws an exception, or if an invocation error occurs.

◆ checkException()

bool checkException ( bool verbose = false )

Determine if a Java exception has been thrown in the current thread.

Parameters

verbose If true, print the exception stack trace to standard error.

Returns: true if an exception has been thrown, false otherwise.

◆ clearException()

void clearException ( )

Clear any pending Java exception that is currently being thrown in the current thread.

◆ createByteArray() [1/2]

jbyteArray createByteArray ( uint_t length )

Create a Java byte array.

Parameters

length The length of the array.

Returns: The array.

Exceptions

JavaException If an error occurs.

◆ createByteArray() [2/2]

jbyteArray createByteArray	(	const byte_t *	data,
		size_t	length
	)

Create a Java byte array.

Parameters

data	The data to copy into the array.
length	The length of the array.

Returns: The newly created array.

Exceptions

JavaException If an error occurs.

◆ createDirectByteBuffer()

jobject createDirectByteBuffer	(	byte_t *	buf,
		size_t	size
	)

Create a new Java DirectByteBuffer.

Parameters

buf	A pointer to the natively-allocated memory block for the buffer.
size	The size of the memory block, in bytes.

Returns: The newly created DirectByteBuffer object.

Exceptions

JavaException If an error occurs.

◆ createGlobalRef()

jobject createGlobalRef ( jobject object )

Create a global reference to a Java object.

Parameters

object The object.

Returns: The new global reference.

Exceptions

JavaException If an error occurs.

◆ createLocalRef()

jobject createLocalRef ( jobject object )

Create a local reference to a Java object.

Parameters

object The object.

Returns: The new local reference.

Exceptions

JavaException If an error occurs.

◆ createObject()

jobject createObject	(	jclass	clazz,
		jmethodID	constructor,
			...
	)

Instantiate a new Java object.

Parameters

clazz	The class.
constructor	The constructor to invoke.

Exceptions

JavaException If the constructor throws an exception, or if an invocation error occurs.

◆ createObjectArray()

jarray createObjectArray	(	jclass	type,
		uint_t	length,
		jobject	initialValue = `NULL`
	)

Create a Java object array.

Parameters

type	The array type.
length	The length of the array.
initialValue	An optional initial value to store into every element in the new array.

Returns: The newly created array.

Exceptions

JavaException If an error occurs.

◆ createObjectVA()

jobject createObjectVA	(	jclass	clazz,
		jmethodID	constructor,
		va_list	args
	)

Instantiate a new Java object.

Parameters

clazz	The class.
constructor	The constructor to invoke.
args	The arguments to pass to the constructor.

Exceptions

JavaException If the constructor throws an exception, or if an invocation error occurs.

◆ decodeString()

String decodeString ( jstring str )

Decode a java.lang.String into a String.

Parameters

str	The Java string.

Returns: The decoded String.

Exceptions

JavaException If an error occurs.

◆ defineClass()

jclass defineClass	(	const String &	name,
		const byte_t *	buf,
		size_t	length
	)

Define a Java class from a buffer of raw bytecode.

Parameters

name	The name of the class.
buf	The byte buffer containing the bytecode.
length	The length of the buffer.

Returns: The new class object.

Exceptions

JavaException If the class could not be loaded.

◆ deleteGlobalRef()

void deleteGlobalRef ( jobject ref )

Delete a local reference.

Parameters

ref	The reference.

◆ deleteLocalRef()

void deleteLocalRef ( jobject ref )

Delete a local reference.

Parameters

ref	The reference.

◆ encodeString()

jstring encodeString ( const String & str )

Encode a String into a java.lang.String.

Parameters

str	The String.

Returns: The encoded Java string.

Exceptions

JavaException If an error occurs.

◆ encodeType()

String encodeType ( const String & type )

static

Encode a datatype into a JNI datatype descriptor.

For example, "String[]" is encoded as "[Ljava/lang/String;".

Parameters

type	The datatype.

Returns: The encoding of the datatype.

◆ ensureLocalCapacity()

void ensureLocalCapacity ( uint_t capacity )

Reserve space for local references.

Parameters

capacity The number of local references to reserve capacity for.

Exceptions

JavaException If an error occurs.

◆ enterMonitor()

void enterMonitor ( jobject object )

Enter the monitor associated with a Java object.

The method blocks if another thread is currently in the monitor.

Parameters

object The object.

Exceptions

JavaException If an error occurs.

◆ exitMonitor()

void exitMonitor ( jobject object )

Exit the monitor associated with a Java object.

Parameters

object The object.

Exceptions

JavaException If an error occurs.

◆ findClass()

jclass findClass ( const String & name )

Look up a class by name.

The class name must be fully qualified (for example, "java.util.Vector"), with the following classes as the only exceptions: String, Object, Class.

Parameters

name	The name of the class.

Returns: A reference to the Java class.

Exceptions

JavaException If the class was not found.

◆ findField()

jfieldID findField	(	jclass	clazz,
		const String &	signature
	)

Look up a field by signature.

The signature must be specified in Java source code form, for example "String name" or "static int foo".

Parameters

clazz	The Java class.
signature	The signature of the field.

Returns: A reference to the field.

Exceptions

JavaException If the field was not found.

◆ findMethod()

jmethodID findMethod	(	jclass	clazz,
		const String &	signature
	)

Look up a method or constructor by signature.

The signature must be specified in Java source code form, without parameter names, for example "int foo(int, byte[])" or "static boolean bar(java.util.Vector, int, String)", or "(int, String, String)" (a constructor).

Parameters

clazz	The Java class.
signature	The signature of the method.

Returns: A reference to the method.

Exceptions

JavaException If the method was not found.

◆ getArrayData()

void * getArrayData	(	jarray	array,
		uint_t &	length,
		bool *	isCopy = `NULL`
	)

Obtain a pointer to the body of a primitive Java array.

This data may be used and modified safely (without any intervening JNI calls) until a matching call to releaseArrayData().

Parameters

array	The primitive array.
length	A parameter in which to store the length of the buffer containing the array data.
isCopy	If not NULL, a pointer in which to store a flag indicating whether the returned buffer is a copy of the array data.

Returns: A pointer to a buffer containing the array data.

Exceptions

JavaException If an error occurs.

◆ getArrayLength()

uint_t getArrayLength ( jarray array )

Get the length of a Java array.

Parameters

array The array.

Returns: The number of elements in the array.

Exceptions

JavaException If an error occurs.

◆ getBooleanField()

bool getBooleanField	(	jobject	object,
		jfieldID	field
	)

Get the value of an boolean field in an Object.

Parameters

object	The object.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getByteField()

byte_t getByteField	(	jobject	object,
		jfieldID	field
	)

Get the value of a byte field in an Object.

Parameters

object	The object.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getCharField()

char16_t getCharField	(	jobject	object,
		jfieldID	field
	)

Get the value of a char field in an Object.

Parameters

object	The object.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getClassForObject()

jclass getClassForObject ( jobject object )

Get the class for a Java object.

Parameters

object The object.

Returns: The class.

◆ getDirectBufferRegion()

void * getDirectBufferRegion	(	jobject	buf,
		uint64_t &	size
	)

Get a pointer to and the size of the memory region occupied by a Java DirectBuffer.

Parameters

buf	The DirectBuffer object.
size	The variable in which to store the size of the memory region.

Returns: A pointer to the beginning of the memory region, or NULL on failure.

◆ getDoubleField()

double getDoubleField	(	jobject	object,
		jfieldID	field
	)

Get the value of a double field in an Object.

Parameters

object	The object.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getException()

jthrowable getException ( )

Get the pending Java exception, if one is currently being thrown in the current thread.

Returns: The exception object, or NULL if none.

◆ getFloatField()

float getFloatField	(	jobject	object,
		jfieldID	field
	)

Get the value of a float field in an Object.

Parameters

object	The object.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getIntField()

int32_t getIntField	(	jobject	object,
		jfieldID	field
	)

Get the value of an int field in an Object.

Parameters

object	The object.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getLongField()

int64_t getLongField	(	jobject	object,
		jfieldID	field
	)

Get the value of a long field in an Object.

Parameters

object	The object.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getObjectArrayElement()

jobject getObjectArrayElement	(	jobjectArray	array,
		uint_t	index
	)

Get an element of a Java object array.

Parameters

array	The array.
index	The index of the element.

Returns: The value of the element.

Exceptions

JavaException If an error occurs.

◆ getObjectField()

jobject getObjectField	(	jobject	object,
		jfieldID	field
	)

Get the value of an Object field in an Object.

Parameters

object	The object.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getShortField()

int16_t getShortField	(	jobject	object,
		jfieldID	field
	)

Get the value of a short field in an Object.

Parameters

object	The object.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getStaticBooleanField()

bool getStaticBooleanField	(	jclass	clazz,
		jfieldID	field
	)

Get the value of a static boolean field in a class.

Parameters

clazz	The class.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getStaticByteField()

byte_t getStaticByteField	(	jclass	clazz,
		jfieldID	field
	)

Get the value of a static byte field in a class.

Parameters

clazz	The class.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getStaticCharField()

char16_t getStaticCharField	(	jclass	clazz,
		jfieldID	field
	)

Get the value of a static char field in a class.

Parameters

clazz	The class.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getStaticDoubleField()

double getStaticDoubleField	(	jclass	clazz,
		jfieldID	field
	)

Get the value of a static double field in a class.

Parameters

clazz	The class.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getStaticFloatField()

float getStaticFloatField	(	jclass	clazz,
		jfieldID	field
	)

Get the value of a static float field in a class.

Parameters

clazz	The class.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getStaticIntField()

int32_t getStaticIntField	(	jclass	clazz,
		jfieldID	field
	)

Get the value of a static int field in a class.

Parameters

clazz	The class.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getStaticLongField()

int64_t getStaticLongField	(	jclass	clazz,
		jfieldID	field
	)

Get the value of a static long field in a class.

Parameters

clazz	The class.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getStaticObjectField()

jobject getStaticObjectField	(	jclass	clazz,
		jfieldID	field
	)

Get the value of a static Object field in a class.

Parameters

clazz	The class.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getStaticShortField()

int16_t getStaticShortField	(	jclass	clazz,
		jfieldID	field
	)

Get the value of a static short field in a class.

Parameters

clazz	The class.
field	The field ID.

Returns: The value of the field.

Exceptions

JavaException If an error occurs.

◆ getStaticStringField()

String getStaticStringField	(	jclass	clazz,
		jfieldID	field
	)

Get the value of a static String field in a class.

Parameters

clazz	The class.
field	The field ID.

Returns: The value of the field as a String.

Exceptions

JavaException If an error occurs.

◆ getStringField()

String getStringField	(	jobject	object,
		jfieldID	field
	)

Get the value of a java.lang.String field in an Object.

Parameters

object	The object.
field	The field ID.

Returns: The value of the field, encoded as a String.

Exceptions

JavaException If an error occurs.

◆ getStringLength()

uint_t getStringLength ( jstring str )

Get the length of a Java string.

Parameters

str	The string.

Returns: The length of the string.

◆ getSuperclass()

jclass getSuperclass ( jclass clazz )

Get the superclass for a Java class.

Parameters

clazz The class.

Returns: The superclass, or NULL if the class is an interface or if it is java.lang.Object.

◆ isAssignableFrom()

bool isAssignableFrom	(	jclass	clazz1,
		jclass	clazz2
	)

Test if an object of a class or interface can be safely cast to a class or interface of another class.

Parameters

clazz1	The class of the object to be cast.
clazz2	The class of the cast.

Returns: true if the cast is valid, false otherwise.

◆ isInstanceOf()

bool isInstanceOf	(	jobject	object,
		jclass	clazz
	)

Test if a Java object is an instance of an interface or another class.

Parameters

object	The object.
clazz	The class or interface.

Returns: true if the object is an instance of the other class or interface, false otherwise.

◆ isSameObject()

bool isSameObject	(	jobject	object1,
		jobject	object2
	)

Test two Java object references for equality.

Parameters

object1	The first object reference.
object2	The second object reference.

Returns: true if the references both refer to the same object, false otherwise.

◆ isVerbose()

bool isVerbose ( ) const

inline

Determine if verbose mode is enabled for this context.

◆ parseSignature()

bool parseSignature	(	const String &	signature,
		String &	method,
		String &	descriptor,
		bool &	isStatic
	)

static

Parse a method signature into a method name, a JNI method descriptor, and a static flag.

For example, "static int foo(int, char[])" results in a method name of "foo", a JNI method descriptor of "(I[C)I", and a static flag of true.

Parameters

signature	The signature to parse.
method	The string in which to place the method name.
descriptor	The string in which to place the JNI method descriptor.
isStatic	The flag in which to store the static flag (true if a `"static"` qualifier is present, false otherwise).

Returns: true if the signature was parsed successfully, false otherwise.

◆ popLocalFrame()

void popLocalFrame ( )

Destroy the topmost local reference frame.

All local references created in the frame will be freed.

◆ pushLocalFrame()

void pushLocalFrame ( uint_t capacity = 8 )

Create a new local reference frame.

Parameters

capacity The minimal local reference capacity of the new frame.

Exceptions

JavaException If an error occurs.

◆ registerNativeMethods()

void registerNativeMethods	(	jclass	clazz,
		const JavaNativeMethod	methods[]
	)

Register native methods for a Java class.

Parameters

clazz	The class.
methods	An array of native methods to register. The last element in the array must have the function field set to NULL.

Exceptions

JavaException If an error occurs.

◆ releaseArrayData()

void releaseArrayData	(	jarray	array,
		void *	data
	)

Release the buffer returned by getArrayData().

The data will be copied back into the original array, if necessary.

Parameters

array	The primitive array.
data	The buffer containing the array data.

◆ setBooleanField()

void setBooleanField	(	jobject	object,
		jfieldID	field,
		bool	value
	)

Set the value of a boolean field in an object.

Parameters

object	The object.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setByteField()

void setByteField	(	jobject	object,
		jfieldID	field,
		byte_t	value
	)

Set the value of a byte field in an object.

Parameters

object	The object.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setCharField()

void setCharField	(	jobject	object,
		jfieldID	field,
		char16_t	value
	)

Set the value of a char field in an object.

Parameters

object	The object.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setDoubleField()

void setDoubleField	(	jobject	object,
		jfieldID	field,
		double	value
	)

Set the value of a double field in an object.

Parameters

object	The object.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setFloatField()

void setFloatField	(	jobject	object,
		jfieldID	field,
		float	value
	)

Set the value of a float field in an object.

Parameters

object	The object.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setIntField()

void setIntField	(	jobject	object,
		jfieldID	field,
		int32_t	value
	)

Set the value of an int field in an object.

Parameters

object	The object.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setLongField()

void setLongField	(	jobject	object,
		jfieldID	field,
		int64_t	value
	)

Set the value of a long field in an object.

Parameters

object	The object.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setObjectArrayElement()

void setObjectArrayElement	(	jobjectArray	array,
		uint_t	index,
		jobject	value
	)

Set an element of a Java object array.

Parameters

array	The array.
index	The index of the element.
value	The new value for the element.

Exceptions

JavaException If an error occurs.

◆ setObjectField()

void setObjectField	(	jobject	object,
		jfieldID	field,
		jobject	value
	)

Set the value of an Object field in an object.

Parameters

object	The object.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setShortField()

void setShortField	(	jobject	object,
		jfieldID	field,
		int16_t	value
	)

Set the value of a short field in an object.

Parameters

object	The object.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setStaticBooleanField()

void setStaticBooleanField	(	jclass	clazz,
		jfieldID	field,
		bool	value
	)

Set the value of a static boolean field in a class.

Parameters

clazz	The class.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setStaticByteField()

void setStaticByteField	(	jclass	clazz,
		jfieldID	field,
		byte_t	value
	)

Set the value of a static byte field in a class.

Parameters

clazz	The class.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setStaticCharField()

void setStaticCharField	(	jclass	clazz,
		jfieldID	field,
		char16_t	value
	)

Set the value of a static char field in a class.

Parameters

clazz	The class.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setStaticDoubleField()

void setStaticDoubleField	(	jclass	clazz,
		jfieldID	field,
		double	value
	)

Set the value of a static double field in a class.

Parameters

clazz	The class.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setStaticFloatField()

void setStaticFloatField	(	jclass	clazz,
		jfieldID	field,
		float	value
	)

Set the value of a static float field in a class.

Parameters

clazz	The class.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setStaticIntField()

void setStaticIntField	(	jclass	clazz,
		jfieldID	field,
		int32_t	value
	)

Set the value of a static int field in a class.

Parameters

clazz	The class.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setStaticLongField()

void setStaticLongField	(	jclass	clazz,
		jfieldID	field,
		int64_t	value
	)

Set the value of a static long field in a class.

Parameters

clazz	The class.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setStaticObjectField()

void setStaticObjectField	(	jclass	clazz,
		jfieldID	field,
		jobject	value
	)

Set the value of a static Object field in a class.

Parameters

clazz	The class.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setStaticShortField()

void setStaticShortField	(	jclass	clazz,
		jfieldID	field,
		int16_t	value
	)

Set the value of a static short field in a class.

Parameters

clazz	The class.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ setStringField()

void setStringField	(	jobject	object,
		jfieldID	field,
		const String &	value
	)

Set the value of a java.lang.String field in an object.

Parameters

object	The object.
field	The field ID.
value	The new value for the field.

Exceptions

JavaException If an error occurs.

◆ throwException()

bool throwException	(	jclass	exception,
		const String &	message
	)

Throw a Java exception.

Parameters

exception	The class of the exception.
message	The exception message.

Returns: true on success, false otherwise.

◆ unregisterNativeMethods()

void unregisterNativeMethods ( jclass clazz )

Unregister all native methods for a Java class.

Parameters

clazz The class.

Friends And Related Function Documentation

◆ JavaVirtualMachine

friend class JavaVirtualMachine

friend

The documentation for this class was generated from the following files:

Public Member Functions

Static Public Member Functions

Friends

Detailed Description

Constructor & Destructor Documentation

◆ JavaContext()

◆ ~JavaContext()

Member Function Documentation

◆ callBooleanMethod()

◆ callByteMethod()

◆ callCharMethod()

◆ callDoubleMethod()

◆ callFloatMethod()

◆ callIntMethod()

◆ callLongMethod()

◆ callNonvirtualBooleanMethod()

◆ callNonvirtualByteMethod()

◆ callNonvirtualCharMethod()

◆ callNonvirtualDoubleMethod()

◆ callNonvirtualFloatMethod()

◆ callNonvirtualIntMethod()

◆ callNonvirtualLongMethod()

◆ callNonvirtualObjectMethod()

◆ callNonvirtualShortMethod()

◆ callNonvirtualVoidMethod()

◆ callObjectMethod()

◆ callShortMethod()

◆ callStaticBooleanMethod()

◆ callStaticByteMethod()

◆ callStaticCharMethod()

◆ callStaticDoubleMethod()

◆ callStaticFloatMethod()

◆ callStaticIntMethod()

◆ callStaticLongMethod()

◆ callStaticObjectMethod()

◆ callStaticShortMethod()

◆ callStaticStringMethod()

◆ callStaticVoidMethod()

◆ callStringMethod()

◆ callVoidMethod()

◆ checkException()

◆ clearException()

◆ createByteArray() [1/2]

◆ createByteArray() [2/2]

◆ createDirectByteBuffer()

◆ createGlobalRef()

◆ createLocalRef()

◆ createObject()

◆ createObjectArray()

◆ createObjectVA()

◆ decodeString()

◆ defineClass()

◆ deleteGlobalRef()

◆ deleteLocalRef()

◆ encodeString()

◆ encodeType()

◆ ensureLocalCapacity()

◆ enterMonitor()

◆ exitMonitor()

◆ findClass()

◆ findField()

◆ findMethod()

◆ getArrayData()

◆ getArrayLength()

◆ getBooleanField()

◆ getByteField()

◆ getCharField()

◆ getClassForObject()

◆ getDirectBufferRegion()

◆ getDoubleField()

◆ getException()

◆ getFloatField()

◆ getIntField()

◆ getLongField()

◆ getObjectArrayElement()

◆ getObjectField()

◆ getShortField()

◆ getStaticBooleanField()

◆ getStaticByteField()

◆ getStaticCharField()