Java Native Interface Specification—Contents

1. Introduction

Java Native Interface Overview
Background

JDK 1.0 Native Method Interface
Java Runtime Interface
Raw Native Interface and Java/COM Interface

Objectives
Java Native Interface Approach
Programming to the JNI
Changes in JDK 1.1.2

2. Design Overview

JNI Interface Functions and Pointers
Loading and Linking Native Methods

Resolving Native Method Names
Native Method Arguments

Referencing Java Objects

Global and Local References
Implementing Local References

Accessing Java Objects

Accessing Primitive Arrays
Accessing Fields and Methods

Reporting Programming Errors
Java Exceptions

Exceptions and Error Codes
Asynchronous Exceptions
Exception Handling

3. JNI Types and Data Structures

Primitive Types
Reference Types
Field and Method IDs
The Value Type
Type Signatures
Modified UTF-8 Strings

4. JNI Functions

Interface Function Table
Version Information

GetVersion

Class Operations

DefineClass
FindClass
GetSuperclass
IsAssignableFrom

Exceptions

Throw
ThrowNew
ExceptionOccurred
ExceptionDescribe
ExceptionClear
FatalError
ExceptionCheck

Global and Local References

NewGlobalRef
DeleteGlobalRef
DeleteLocalRef
EnsureLocalCapacity
PushLocalFrame
PopLocalFrame
NewLocalRef

Weak Global References

NewWeakGlobalRef
DeleteWeakGlobalRef

Object Operations

AllocObject
NewObject, NewObjectA, and NewObjectV
GetObjectClass
IsInstanceOf
IsSameObject

Accessing Fields of Objects

GetFieldID
Get<type>Field Routines
Set<type>Field Routines

Calling Instance Methods

GetMethodID
Call<type>Method Routines, Call<type>MethodA Routines, and Call<type>MethodV Routines
CallNonvirtual<type>Method Routines, CallNonvirtual<type>MethodA Routines, and CallNonvirtual<type>MethodV Routines

Accessing Static Fields

GetStaticFieldID
GetStatic<type>Field Routines
SetStatic<type>Field Routines

Calling Static Methods

GetStaticMethodID
CallStatic<type>Method Routines, CallStatic<type>MethodA Routines, and CallStatic<type>MethodV Routines

String Operations

NewString
GetStringLength
GetStringChars
ReleaseStringChars
NewStringUTF
GetStringUTFLength
GetStringUTFChars
ReleaseStringUTFChars
GetStringRegion
GetStringUTFRegion
GetStringCritical
Release StringCritical

Array Operations

GetArrayLength
NewObjectArray
GetObjectArrayElement
SetObjectArrayElement
New<PrimitiveType>Array Routines
Get<PrimitiveType>ArrayElements Routines
Release<PrimitiveType>ArrayElements Routines
Get<PrimitiveType>ArrayRegion Routines
Set<PrimitiveType>ArrayRegion Routines
GetPrimitiveArrayCritical
ReleasePrimitiveArrayCritical

Registering Native Methods

RegisterNatives
UnregisterNatives

Monitor Operations

MonitorEnter
MonitorExit

NIO Support

NewDirectByteBuffer
GetDirectBufferAddress
GetDirectBufferCapacity

Reflection Support

FromReflectedMethod
FromReflectedField
ToReflectedMethod
ToReflectedField

Java VM Interface

GetJavaVM

5. The Invocation API

Overview

Creating the VM
Attaching to the VM
Unloading the VM

Library and Version Management

JNI_OnLoad
JNI_OnUnload

Invocation API Functions

JNI_GetDefaultJavaVMInitArgs
JNI_GetCreatedJavaVMs
JNI_CreateJavaVM
DestroyJavaVM
AttachCurrentThread
AttachCurrentThreadAsDaemon
DetachCurrentThread
GetEnv