Error a Jni Error Has Occurred Please Check Your Installation and Try Again Applicationlistener

I know how frustrating is to see Exception in thread "main" java.lang.NoClassDefFoundError,  which is a manifestation of NoClassDefFoundError in Java. I have seen it a couple of times and spent quite a lot of time initially to figure out what is wrong, which class is missing etc. The kickoff mistake I did was mingling java.lang.ClassNotfoundException and NoClassDefFoundError, in reality, are totally different, and my second mistake was using the trial and error method to solve this java.lang.NoClassDefFoundError instead of understanding why NoClassDefFoundError is coming, what is the real reason behind NoClassDefFoundError and how to resolve this.

In this Java tutorial, I accept tried to rectify that mistakes and uncover some secrets of NoClassDefFoundError in Java and will share my experience around information technology. NoClassDefFoundError is not something that cannot be resolved or is hard to resolve information technology's simply its manifestation that puzzles almost Java developers.

This is the most common mistake in Coffee development along with java.lang.OutOfMemoroyError: Coffee heap infinite and java.lang.OutOfMemoryError: PermGen space Anyway lets run into Why NoClassDefFoundError comes in Java and what to do to resolve NoClassDefFoundError in Java.

What is the reason for NoClassDefFoundError in Java?

NoClassDefFoundError in Coffee comes when Java Virtual Machine is not able to find a item course at runtime which was available at compile time. For instance, if we have a method call from a grade or accessing any static member of a grade and that class is not available during run-time so JVM will throw NoClassDefFoundError .

It's of import to empathise that this is different than ClassNotFoundException which comes while trying to load a class at run-fourth dimension but and the proper name was provided during runtime, not at compile-time. Many Coffee developer mingles this two Error and gets confused.

In short, NoClassDefFoundError will come if a grade was present during compile time but not bachelor in java classpath during runtime. Normally you lot will see the below line in the log when y'all get NoClassDefFoundError:

Exception in thread "main" java.lang.NoClassDefFoundError

Exception in thread "master" simply indicates that information technology'southward the "main" thread that is not able to find a detail class information technology could exist any thread so but don't worry. The difference betwixt this error coming in the chief thread and another thread is when Exception in thread "main" comes plan crashes or shut itself downwardly equally opposed to other thread in which example your programme will go along to run.

If you are actually curious and think that you lot empathize how class loading works, I suggest y'all attempt some puzzles from Joshua Bloch's Coffee Puzzlers, information technology has got some really tricky questions to test your knowledge.

The difference between java.lang.NoClassDefFoundError and ClassNotFoundException in Java

Many times we confused ourselves with j ava.lang.ClassNotFoundException and java.lang . NoClassDefFoundError , though both of them are related to Java Classpath they are completely different from each other.

ClassNotFoundException comes when JVM tries to load a class at runtime dynamically means you give the name of the grade at runtime and and then JVM tries to load it and if that course is not institute in the classpath information technology throws java.lang.ClassNotFoundException.

While in the case of NoClassDefFoundError the problematic course was present during Compile time and that's why the program successfully compiled simply was not available during runtime for any reason.

NoClassDefFoundError is easier to solve than ClassNotFoundException in my opinion considering hither we know that Class was present at build fourth dimension, just information technology totally depends upon the surroundings if you are working in the J2EE environment then you can go NoClassDefFoundError even if the class is present because it may not be visible to the respective form loader. Run across my post NoClassDefFoundError vs ClassNotFoundException in Coffee for more details.

How to resolve java.lang.NoClassDefFoundError in Java

The obvious reason for NoClassDefFoundError is that a detail class is not available in Classpath, so we need to add that into Classpath or we demand to check why it'southward not bachelor in Classpath if we are expecting it to be. There could be multiple reasons like:

ii) You might be running your program using the jar control and form was not defined in the manifest file's ClassPath attribute.

3) Whatever start-up script is an overriding Classpath surroundings variable.

4) Considering NoClassDefFoundError is a bracket of java.lang.LinkageError it tin also come if ane of it dependency like native library may not available.

4) Check for java.lang.ExceptionInInitializerError in your log file. NoClassDefFoundError due to the failure of static initialization is quite common.

5) If you are working in J2EE environment than the visibility of Grade amid multiple Classloader can as well cause coffee.lang.NoClassDefFoundError , see examples and scenario department for detailed discussion.

We will now encounter a couple of examples and scenarios when java.lang.NoClassDefFoundError has come before and how it'due south been resolved. This tin can aid y'all to troubleshoot the root crusade of NoClassDefFoundError in Coffee awarding.

NoClassDefFoundError in Java - Instance and Scenarios

i. A uncomplicated example of NoClassDefFoundError is grade belongs to a missing JAR file or JAR was not added into classpath or sometimes jar's name has been changed by someone like in my case ane of my colleagues has changed tibco.jar into tibco_v3.jar and the plan is failing with java.lang.NoClassDefFoundError and I were wondering what'southward incorrect.

two. The class is non in Classpath, there is no sure-shot way of knowing it but many times you can but have a wait to impress Organisation.getproperty("java.classpath") and it will impress the classpath from there you can at to the lowest degree get an idea of your actual runtime classpath.

iii. Just attempt to run with explicitly -classpath selection with the classpath you think will work and if it'due south working then it's a sure shot sign that someone is overriding java classpath.

NoClassDefFoundError in Java due to Exception in Static Initializer block

This is another common reason for java.lang.NoClassDefFoundError , when your class performs some static initialization in a static block like many Singleton classes initialized itself on the static block to take reward of thread-rubber provided by JVM during the class initialization process, and if static cake throws an Exception, the class which is referring to this class will get NoclassDefFoundError in Coffee.

If you wait at your log file yous should spotter for whatever java.lang.ExceptionInInitializerError because that could trigger java.lang.NoClassDefFoundError: Could non initialize class on other places.

Similar in the beneath lawmaking example, During class loading and initialization User class are throwing Exception from the static initializer block, which triggers ExceptionInInitializerError during the first time loading of User grade in response to new User() phone call.

Later rest of new User() are failing every bit j ava.lang.NoClassDefFoundError . the situation gets worst if original ExceptionInInitializerError , which is root cause here is silently eaten past whatsoever lawmaking.

Code Case of NoClassDefFoundError due to Static block Exception:

/**
 * Java plan to demonstrate how failure of static initialization subsequently cause
 * java.lang.NoClassDefFoundError in Coffee.
 * @author Javin Paul
 */
public class NoClassDefFoundErrorDueToStaticInitFailure { public static void main ( String args []){

        List

< User > users = new ArrayList < User > ( 2 ) ; for ( int i= 0 ; i < 2 ; i++ ){
attempt {
            users. add together ( new User ( String . valueOf ( i ))) ; //volition throw NoClassDefFoundError
} take hold of ( Throwable t ){
                t. printStackTrace () ;
}
}
}
} class User {
private static String USER_ID = getUserId () ; public User ( String id ){
this . USER_ID = id ;
}
private static String getUserId () {
throw new RuntimeException ( "UserId Not found" ) ;
}
}

Output
java.lang.ExceptionInInitializerError
    at testing.NoClassDefFoundErrorDueToStaticInitFailure.chief (NoClassDefFoundErrorDueToStaticInitFailure.java:23 )
Caused past: java.lang.RuntimeException: UserId Not found
    at testing.User.getUserId (NoClassDefFoundErrorDueToStaticInitFailure.java:41 )
    at testing.User.<clinit> (NoClassDefFoundErrorDueToStaticInitFailure.java:35 )
    ... one more
java.lang.NoClassDefFoundError: Could not initialize class testing.User
    at testing.NoClassDefFoundErrorDueToStaticInitFailure.main (NoClassDefFoundErrorDueToStaticInitFailure.java:23 )

5) Since NoClassDefFoundError is an also a LinkageError that arises due to dependency on some other class, you tin also become java.lang.NoClassDefFoundError if your programme is dependent on the native library and the corresponding DLL is non there. Remember this can also trigger java.lang.UnsatisfiedLinkError: no dll in coffee.library.path Exception Java . In guild to solve this keep your dll along with JAR.

6) If you lot are using the ANT build file create JAR and manifest file and so its worth noting to debug till that level to ensure that Pismire build script is getting the right value of classpath and appending information technology to manifest.mf file .

7) Permission outcome on the JAR file can too cause NoClassDefFoundError in Java. If you lot are running your Java program in a multi-user operating system similar Linux then you should be using the application user id for all your application resources similar JAR files, libraries, and configuration.

If you lot are using a shared library which is shared among multiple application which runs under different users then you may run into permission upshot, like JAR file is endemic by some other user and not accessible to your application.

One of our readers "it's me said", faced java.lang.NoClassDefFoundError due to this reason. Run into his annotate besides.

viii) Typo on XML Configuration tin can also cause NoClassDefFoundError in Java. As near of Java frameworks like Spring, Struts they all employ XML configuration for specifying beans. By any run a risk, if you lot put the bean name wrong, it may surface as java.lang.NoClassDefFoundError while loading other class which has a dependency on the wrongly named bean.

This is quite mutual in the Spring MVC framework and Apache Struts where y'all get tons of Exception in thread "main" coffee.lang.NoClassDefFoundError, while deploying your WAR or EAR file.

9) Another example of coffee.lang.NoClassDefFoundError, as mentioned past our reader Nick, is that when your compiled course which is defined in a package, doesn't present in the same packet while loading like in the case of JApplet it will throw NoClassDefFoundError in Java. As well, see Nick's comment on this error.

x) java.lang.NoClassDefFoundError can be caused due to multiple classloaders in J2EE environments. Since J2EE doesn't mention standard classloader structure and it depends on dissimilar vendors like Tomcat , WebLogic , WebSphere on how they load dissimilar components of J2EE like WAR file or EJB-JAR file.

In gild to troubleshoot NoClassDefFoundError in the J2EE awarding knowledge of How ClassLoader works in Java is mandatory. But to recap ClasLoader works on three principles delegation, visibility, and uniqueness.

Delegation ways every request to load a class is delegated to the parent classloader, visibility means an power to plant classes loaded by the classloader, all kid classloaders tin can encounter classes loaded past parent classloader, just parent classloader can not see the grade loaded by kid classloaders.

Uniqueness enforces that form loaded by the parent will never exist reloaded past child classloaders. At present suppose if a class says User is nowadays in both WAR file and EJB-JAR file and loaded by WAR classloader which is child classloader which loads the grade from EJB-JAR. When a code in EJB-JAR refers to this User class, Classloader which loaded all EJB class doesn't institute that because it was loaded past WAR classloader which is a child of it.

This will result in java.lang.NoClassDefFoundError for User class. As well, If the class is present in both JAR file and y'all will call equals method to compare those two objects, it will consequence in ClassCastException every bit the object loaded past two different classloaders tin non exist equal.

eleven) Some of the readers of this blog also suggested that they go Exceptions in thread "main" java.lang.NoClassDefFoundError: com/sunday/tools/javac/Primary , this mistake means either your Classpath, PATH  or JAVA_HOME is not setup properly or JDK installation is not correct. which can be resolved by reinstalling JDK?

If you lot are getting this error effort to reinstall JDK. 1 of our readers got this outcome after installing jdk1.vi.0_33 and then reinstalling JDK1.6.0_25, he also has his JRE and JDK in a different folder. See his comment also by searching JDK1.6.0_33.

12) Java programme can also throw coffee.lang.NoClassDefFoundError during linking which occurs during class loading in Java. I of the examples of this scenario is just deleted the User class from our static initializer failure example after compilation and they try to run the plan.

This time, you volition get java.lang.NoClassDefFoundError directly without java.lang. ExceptionInInitializerError and message for NoClassDefFoundError are also but printing the name of the class as testing/User i.e. User grade from the testing parcel. Sentinel out for this advisedly as here root crusade is absent of User.class file.

coffee.lang.NoClassDefFoundError: testing/User
    at testing.NoClassDefFoundErrorDueToStaticInitFailure.main(NoClassDefFoundErrorDueToStaticInitFailure.coffee:23)

Permit me know how exactly y'all are facing NoClassDefFoundError in Coffeeand I will guide yous on how to troubleshoot information technology if you are facing something new way than I listed above we will probably document it for the benefit of others and again don't be agape with Exception in thread "principal" java.lang.NoClassDefFoundError.

Other Exception and Mistake handling Tutorials from Javareivisted

• How to solve UnSupportedClassVersionError in Java
• Java.net.BindException: Accost already in use: JVM_Bind:8080 Solution
• JDBC - java.lang.ClassNotFoundException: com.mysql.jdbc.Driver Solution
• How to Gear up java.lang.classnotfoundexception oracle.jdbc.driver.oracledriver
• How to solve coffee.lang.ClassNotFoundException: org.Springframework.Spider web.Context.ContextLoaderListener
• How to prepare coffee.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory
• How to solve java.lang.ClassNotFoundException: com.mysql.jdbc.Driver

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Source: https://javarevisited.blogspot.com/2011/06/noclassdeffounderror-exception-in.html

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