Every program I run in java gives similiar error.
This is a helloworld program:
Exception in thread "main" java.lang.NoClassDefFoundError: helloworld (wrong nam
e: helloworldapp)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(Unknown Source)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$000(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
Could not find the main class: helloworld. Program will exit.
The class file helloworld.class contains a class called helloworldapp.class. The only real reason for this that I can think of is that you manually renamed the .class file.
That won't work! A class called helloworldapp must be found in a .class file called helloworldapp.class.
If you want to change the name of the class, rename the .java source file, edit the class definition and recompile it.
Try this one:
public class HelloWorld
{
public static void main(String[] args)
{
System.out.println("Hello World!");
}
}
Read this tutorial about this problem.
How do you start the Java program? Are you passing the arguments correctly? Pay attention to the class path. If you have helloworld.java file and have compiled it to helloworld.class, you should run it like this (from a command prompt in the same directory the class file is located):
java -cp . helloworld
Related
I recently moved a project from one machine to another but I am now given an error when attempting to run java files on the new machine. I'm trying to run a java file from part of an Android project in command prompt but I am given an error. The file compiles okay but fails to run. Here is the error I am given;
Exception in thread "main" java.lang.NoClassDefFoundError: ChatServer (
e: edu/UTEP/android/ChatServer)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)
Any ideas why I am receiving this error?
Your ChatServer is having a package declaration of edu.UTEP.android in the top. So either you need to remove that package declaration recompile your java file again and run it
(or)
you need to create folder structure like this
CurrentDir/edu/UTEP/android/
Keep your java file in android folder and invoke java ChatServer from CurrentDir. Any of these two will solve the issue :-)
For more info on packages, you can refer to my previous answer on a similar issue here
Make sure that the .jar that provides ChatServer is in your runtime Classpath.
This issue rise when jvm don't file class path.
check where u have placed your jar file or lib folder.
Move to that directory then run javac and then java .
Issue will be resolved.
i'm new to java.
i've created a file called HelloWorld.java;
package tp;
/**
*
* #author Utilisateur
*/
public class HelloWorld {
public static void main(String[] args) {
System.out.println("HelloWorld works!");
}
}
compiled it by executing the command: javac HelloWorld.java in the same folder as HelloWorld.java is in;
executed the code by doing: java -cp . HelloWorld in the same folder as HelloWorld.java is in.
but i get this error message
Exception in thread "main" java.lang.NoClassDefFoundError: HelloWorld (wrong nam
e: javaTp/HelloWorld)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)
can anyone help?
The package name is your issue.
Java uses directories in compiled class folders to denote packages. Hence as your HelloWorld class defines itself as being in package 'tp', you need to do one of the following:
You can either run this (with your existing class):
> java -cp . tp.HelloWorld
Or you can remove the package declaration from the top of your class, recompile and run:
> java -cp . HelloWorld
Because you declared the package tp, Java expects your HelloWorld.class file to live in a directory ./tp.
Typically a Java project will have a nested directory structure compiled to a mirrored one, such as:
src/
tp/
HelloWorld.java
classes/
tp/
HelloWorld.class
You need to use the full name: java tp.HelloWorld
Hi I have made a runnable JAR file useing export option on eclipse. However, when I go to run the file via command prompt i get the following
Exception in thread "main" java.lang.NoSuchMethodError
at org.eclipse.jdt.internal.jarinjarloader.RsrcURLConnection.getInputStream(RsrcURLConnection.java:43)
at java.net.URL.openStream(Unknown Source)
at sun.misc.URLClassPath$Loader.getResource(Unknown Source)
at sun.misc.URLClassPath.getResource(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoader.java:56)
Does any one have any ideas as to what im doing wrong? pretty new to the whole creating runnable files etc.
Your jar is compiled with a newer version of java than the computer you are running it on.
Extract the jar file look for the file META-INF/MANIFEST-MF. This file should have an entry
Main-Class : <you fully qualified classname having main method>
Check if the class you mentioned as Main-Class has a main method (public static void main(String[] arg))
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Can I run from command line program created by Eclipse?
I am getting below exception when I try to run class file from command prompt,the same I run in eclipse,there I don't get any error
Trying to run from the same folder
Exception in thread "main" java.lang.NoClassDefFoundError: testClient (wrong nam
e: com/mindcraft/queryExecutor/actionclass/testClient)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(Unknown Source)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$000(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
Could not find the main class: testClient. Program will exit.
I suspect you're running in a directory of com/mindcraft/queryExecutor/actionclass
Instead, you should be running in the root directory (i.e. the parent of com), like this:
java com.mindcraft.queryExecutor.actionclass.testClient
run the .class file from root directory with full name space. i.e, if your class is in com.test package as com.test.App.java in your src then on compiling its class file will have a qualified class name as full name. i.e, com.test.App.class
So from your root/src run it as java com.test.App in command line.
Before posting a question kindly Search enough if the question has been asked before or even better answered before. When i Googled i found a similar question being answered. Hope the link provides you the answer you are looking for
I am trying execute a java class which accesses a method in a jar file.My package structure is com.xmlpost.XmlPostInit.java and it resides under the directory:
D:\Workspace\Test\bin
I am using the command below. Note, cs.jar contains the class com.xmlpost.XmlPostInit
D:\Workspace\Test\bin>java -classpath D:\FatWire\JSK\7.6.0\App_Server\apache-tomcat-6.0.18\webapps\cs\WEB-INF\lib\cs.jar com.xmlpost.XmlPostInit
.. which gives me following error:
Exception in thread "main" java.lang.NoClassDefFoundError: com/xmlpost/XmlPostInit
Caused by: java.lang.ClassNotFoundException: com.xmlpost.XmlPostInit
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
Could not find the main class: com.xmlpost.XmlPostInit. Program will exit.
You have to add your bin directory to the classpath too, as the JVM needs to look inside it to find your class. As you are running inside it, you can refer localy it with ".":
D:\Workspace\Test\bin>java -classpath .;D:\FatWire\JSK\7.6.0\App_Server\apache-tomcat-6.0.18\webapps\cs\WEB-INF\lib\cs.jar com.xmlpost.XmlPostInit