How do I resolve ClassNotFoundException

Question

I am trying to run a Java application  but getting this error    java lang ClassNotFoundException    After the colon comes the location of the class that is missing  However  I know that that location does not exist since the class is located elsewhere  How can I update the path of that class  Does it have something to do with the class path

User · Accepted Answer

Your classpath is broken  which is a very common problem in the Java world      Depending on how you start your application  you need to revise the argument to -cp  your Class-Path entry in MANIFEST MF or your disk layout

User · Answer

If you have moved your project to new machine or importing it from git  then try this   Right Click on class  gt  Run as  gt  Run Configuration remove main class reference Apply  gt  Close Now again right click on class  gt  run as java application   It worked for me

User · Answer

This can happen on Windows after a java update where the old version of the java SDK is missing and a new one is present  I would check if your IDE is using the installed java SDK version  IntelliJ  CTRL   SHIFT   ALT   S

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In my case the class thrown as class not found exception has properties related to ssl certificates  Close the eclipse and open with as    Run as Administrator    then issue got resolved  As eclipse have issue related permission it will throw such kind of exception

User · Answer

I deleted some unused imports and it fixed the problem for me  You can t not find a Class if you never look for it in the first place

User · Answer

If you know the path of the class or the jar containing the class then add it to your classpath while running it  You can use the classpath as mentioned here   on Windows  java -classpath   yourjar jar YourMainClass   on UNIX Linux  java -classpath   yourjar jar YourMainClass

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It could happen if your classpath is not correct   Let us posit a serializable class and deserializable class under same projectname  You run the serializable class  creating a serializable object in specific folder  Now you need the desearialized data  In the meantime  if you change the name of the project it will not work  You have to run the serializable class first and then deserialize the file

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Use     as the separator  If your environment variables are set correctly  you should see your settings  If your PATH and CLASSPATH is correct  windows should recognize those commands  You do NOT need to restart your computer when installing Java

User · Answer

Add the full path of jar file to the CLASSPATH  In linux use  export CLASSPATH     full path to file jar  CLASSPATH   Other way worked  without editing the CLASSPATH  was unzipping the jar in the current project folder   Ways didn t work for me   1  Using -cp option with full path of jar file   2  Using -cpwith only the name of jar when located in the current folder  3  Copying the jar to the current project folder  4  Copying the jar to standard location of java jars   usr share java   This solution is reported for class com mysql jdbc Driver in mysql-connector-java 5-  jar  working on linux with OpenJDK version 1 7

User · Answer

Go up to the top and remove the import statement if there is one  and re import the class   But if that isn t the case do a clean then build   Are you using Netbeans or Eclipse

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To add the location of a class to your classpath via command line simply add -cp or -classpath and the location of the class while running it  I E   java -cp  c  location of file  YourProgram   Or if you re running an IDE such as eclipse you can right click on the project - gt  build path - gt  configure build path and add the external JAR containing your class to the build path then it should work fine

User · Answer

I just did    1 Invalidate caches and restart   2 Rebuilt my project which solved the problem

User · Answer

I ran into this as well and tried all of the other solutions  I did not have the  class file in my HTML folder  I only had the  java file  Once I added the  class file the program worked fine

User · Answer

Try these if you use maven  I use maven for my project and when I do mvn clean install and try to run a program it throws the exception  So  I clean the project and run it again and it works for me    I use eclipse IDE   For Class Not Found Exception when running Junit test  try running mvn clean test once  It will compile all the test classes

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If you use maven  check that you have this plugin in your pom xml        lt build gt           lt plugins gt                lt plugin gt                   lt groupId gt org apache maven plugins lt  groupId gt                   lt artifactId gt maven-shade-plugin lt  artifactId gt                   lt version gt 3 2 0 lt  version gt                   lt executions gt                       lt  -- Attach the shade goal into the package phase -- gt                       lt execution gt                           lt phase gt package lt  phase gt                           lt goals gt                               lt goal gt shade lt  goal gt                           lt  goals gt                       lt  execution gt                   lt  executions gt               lt  plugin gt            lt  plugins gt       lt  build gt    It will put your dependency  the exception reason  to your jar   FYI  this will include all dependencies inflated in the final jar

User · Answer

A classpath is a list of locations to load classes from    These  locations  can either be directories  or jar files    For directories  the JVM will follow an expected pattern for loading a class  If I have the directory C  myproject classes in my classpath  and I attempt to load a class com mycompany Foo  it will look under the classes directory for a directory called com  then under that a directory called mycompany  and finally it will look for a file called Foo class in that directory   In the second instance  for jar files  it will search the jar file for that class  A jar file is in reality just a zipped collection of directories like the above  If you unzip a jar file  you ll get a bunch of directories and class files following the pattern above    So the JVM traverses a classpath from start to finish looking for the definition of the class when it attempts to load the class definition  For example  in the classpath    C  myproject classes C  myproject lib stuff jar C  myproject lib otherstuff jar  The JVM will attempt to look in the directory classes first  then in stuff jar and finally in otherstuff jar   When you get a ClassNotFoundException  it means the JVM has traversed the entire classpath and not found the class you ve attempted to reference  The solution  as so often in the Java world  is to check your classpath   You define a classpath on the command line by saying java -cp and then your classpath  In an IDE such as Eclipse  you ll have a menu option to specify your classpath

User · Answer

Put all the code in try block then catch exception in a catch block  try          code   catch ClassNotFoundException e1        e1 getmessage

User · Answer

I was trying to run  jar from C  code using Process class  The java code ran successfully from eclipse but it doesn t from C  visual studio and even clicking directly on the jar file  it always stopped with ClassNotFoundException  exception  Solution for my  was export the java program as  Runnable JAR file  instead of  JAR File   Hope it can help someone

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If you have added multiple  Third-Party   libraries and Extends   Application class  Then it might occur   For that  you have to set multiDexEnabled true and replace your extended Application class with  MultiDexApplication   It will be solved

User · Answer

If you are using maven  try to maven update all projects and force for snapshots  It will clean as well and rebuilt all classpath   It solved my problem

User · Answer

sorry i am late to the question  but i will explain it to you in the simplest layman language  When you type  javac  lt programname java gt  The compiler checks the program and finds errors  first of all make sure your program is in the same directory as you have executed in the command prompt  Then it creates a  Class file of your program  For ex  If the name of my program was Test java then the class file created should be Test class which will be executed in the next line  Sometimes java takes some other name for your  class  use that name and voila you ll get the output

User · Answer

I started having this issue after upgrading the  quot Java Language Support quot  plugin from Visual Studio Code from version 0 66 0 to 0 67 0  Downgrading back allowed me to run the same code without any issue

User · Answer

Basic Generic Question - Simplest Generic Answer     Given the information I will make the assumption that you might be trying a basic approach to coding  building compiling and running a simple console app like  Hello World   using some simple text editor and some Command Shell   This error occurs in the fallowing scenario      SomePath gt javac HelloWorld java    SomePath gt java HelloWorld class   In other words  use      SomePath gt java HelloWorld   P S  The adding the file extension  class produces the same mistake  Also be sure to have the Java s  JDK JRE  bin folder in the operating system s Environment Variables s PATH  Lookup for more details other posts on this  P P S Was I correct in my assumption s

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This is the best solution I found so far   Suppose we have a package called org mypackage containing the classes    HelloWorld  main class    SupportClass  UtilClass   and the files defining this package are stored physically under the directory D  myprogram  on Windows  or  home user myprogram  on Linux    The file structure will look like this    When we invoke Java  we specify the name of the application to run  org mypackage HelloWorld  However we must also tell Java where to look for the files and directories defining our package  So to launch the program  we have to use the following command       NOTE  You have to execute the above java command no matter what your current location is  But this is not the case for javac  For   compiling you can even directly go into the directory where you have   your  java files and directly execute javac ClassName java

[java] How do I resolve ClassNotFoundException?

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