Java Native Interface (JNI) Interview Questions & Answers

Question 1. What Is Native Interface In Java?

Answer :

JNI is the mechanism used to invoke methods written in languages such as c and C++. You can write code using language like c and c++ and declare its native methods and can use the same method in java using JNI.

JNI exposes JNI functions and pointers that can access java objects and methods.

Question 2. Are There Jvm’s That Work As A True 64-bit Application?

Answer :

IBM’s SDK for Windows on Itanium Solaris TM-SPARCTM platform edition of J2SDK 1.4.0 CACAO is 64 bit just-in-time (JIT) compiler for Java.

Question 3. Define Jni Functions And Pointers?

Answer :

JNI functions are those which are used by the developers to interact with JVM within a native method. Every JNI function receives a special parameter as its first argument – JNIEnv ; which points to a special JNI data structure of the type JNIEnv_ . One of the elements of JNI data structure is a ‘pointer to an array’ generated by JVM, and each element of this array is again a pointer to a JNI function.

A JNI function can be invoked from the native method by referencing these pointers. Every JVM provides a unique implementation of the JNI functions.

Question 4. What Is Swt?

Answer :

SWT is the software component (part of the Eclipse IDE Framework) that delivers native widget functionality for the Eclipse platform in an operating.

Question 5. Explain The Advantages And Disadvantages Of Using Jni?

Answer :

Advantages of JNI

• Using JNI, we can access c and c++ code which adds performance boost to JAVA.
• JNI allows JAVA to access some hardware features using other languages like c and c++.

Disadvantages of JNI

• JNI uses native languages which mean it has portability issue.
• Code debug is big problem for the developers who use JNI features in JAVA.

Question 6. What Is Jni?

Answer :

JNI stands for Java Native Interface. It is an interface between Java, applications and libraries that are written in other languages. JNI is solely used to interact with “native” code (code written in system level language such as C). For instance, JNI enables the usage of C libraries and C programs to be used in Java programs.

Question 7. What Is Jawin?

Answer :

The Java/Win32 integration project is free, open source architecture for interoperation between Java and components exposed through Microsoft.

Question 8. Explain Exception Handling In Jni?

Answer :

JNI exceptions are handled by using the following:

• Throw( ): Throws an existing exception object. Used in native methods to rethrow an exception.
• ThrowNew( ): Creates a new exception object and throws.
• ExceptionOccurred( ): Determines the exception status of throws and not yet cleared.
• ExceptionDescribe( ): Displays the exception and stack trace
• ExceptionClear( ): A pending exception is cleared.
• FatalError( ): Causes a fatal error to raise and does not return.

Question 9. How Can I Create Standalone Java Applications That Can Be Launched Just Like Any Other Mac Os Application?

Answer :

You can use JManager API or JBindery to do so. Here’s an article that shows you how to create a wrapper program around a Java application:

Question 10. Is There A Tcl-java Bridge?

Answer :

Yes, The Tcl/Java project currently has two packages, Jacl and Tcl Blend. Jacl, which stands for Java Command Language, is a Java implementation of Tcl…

Question 11. How Can I Access Java From Python (and The Other Way Around)? Are There Any Jni Wrappers Which Can Bridge The Gap Between The Two?

Answer :

JPE (Java-Python Extension) is an open-source effort for seamless inter-operability between Java and Python. Java-Python Extension main site JPE.

Question 12. Is There An Alternative To Jni On Macos?

Answer :

If you want to call Mac OS C code from your Java code, there are currently two mechanisms for doing so: JDirect2 and the Java Native Interface (JNI).