The error image
Error: Could not find or load main class JDBCExample1.java
Caused by: java.lang.ClassNotFoundException:JDBCExample1.java
Batch file used:
set path=C:\Program Files\Java\jdk-10.0.2\bin;
set classpath=C:\oraclexe\app\oracle\product\11.2.0\server\jdbc\lib\ojdbc14.jar;.
javac JDBCExample1.java
java JDBCExample1.java
pause
The PATH and the CLASSPATH have been set correctly in Environment variables too.
Also the directory used is correct.
Try giving
“java JDBCExample1”
Instead of
“java JDBCExample1.java”
In the last line. One does not use .java while running the program
I have a problem while trying executing my java application.
Whenever I try to execute the program through the command
java ProgAudioJ
I get this error:
Exception in thread "main"
java.lang.NoClassDefFoundError: ProgAudioJ (wrong name: es_2011/ProgAudioJ)
at java.lang.ClassLoader.defineClass1(NativeMethod)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
at java.security.AccessController.doPrivileged(NativeMethod)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
Could not find the main class: ProgAudioJ. Program will exit.
If I remove from my code:
package es_2011;
Everything works perfectly. How do I solve the problem?
Because I found these answers unclear, here is what you need to do.
First, if you package your code (IE your classes have the package keyword at the top) the compiled classes have to be in a directory with the same name as your package declaration in code. After you have compiled your classes, you need to move up a directory when you exectute the java command, and you include the name of the package. For example, if your code exists in /myFolder/myPackage/ , and your class starts with package myPackage (note that the directory and the package are the same name), then you would do the following (linux / osx):
cd /myFolder/myPackage
javac MyClass.java
cd ..
java myPackage.MyClass
Edit - A late edit to clarify something I see people get confused on. In the example above, the package is only one deep, meaning its just myPackage. If you code has a larger package, like
package com.somedomain.someproject;
you will need to execute the java command from the directory which contains the root directory for that package. For example if your compiled code is in myCode/com/somedomain/someproject/MyMainClass.class, then you will execute the java command from the myCode folder, like this (Again, take special note that the directory structure is the same as the package declaration):
cd /myCode
java com.somedomain.someproject.MyMainClass
Try using:
java es_2011.ProgAudioJ
(instead of java ProgAudioJ).
I'm making some assumptions here about your current working directory and your CLASSPATH. If you can provide information about the command you're running (e.g. what directory you're in, where the class file is located, etc.), we can help you more efficiently.
Try this (compile and run):
dir
2011-02-10 00:30 <DIR> .
2011-02-10 00:30 <DIR> ..
2011-02-10 00:27 58 es_2011
javac es_2011/ProgAudioJ
java es_2011.ProgAudioJ
It's quite clearly stated there:
java.lang.NoClassDefFoundError: ProgAudioJ (wrong name: es_2011/ProgAudioJ)
If you want to put a class in a package(*), then the source code must be placed in a corresponding directory, e.g.,
src/Main.java <- root package (no declaration)
src/es_2011/ProgAudioJ.java <- package es_2011;
(*) You should do it always, except for tiny throw-away stuff and possibly for the main class.
Try this,
Compile your class using below command
$ javac ProgAudioJ.java -d .
Run your application by command
$ java es_2011.ProgAudioJ
The reason that it works when you remove
package es_2011
is that you are changing how the compiler packages up, and effectively locates, the file.
I had the same problem - and the error message wrong name: does indeed point you to the answer. You are using the wrong name "ProgAudioJ" in order to run the .class file.
It has been packaged up as
es_2011/ProgAudioJ
In order to run it - you have to either move up a directory:
If you are here: (Windows)
src\es_2011\
move to
src\
Then run the line:
java es_2011.ProgAudioJ
This tells the compiler to look for the ProgAudioJ - which resides in the es_2011 package. For a standard installation, this will be based on folders - so it will look for the es_2011 folder first, and then the name of the .class file that you want to run (ProgAudio).
I managed to successfully compile my code, but I'm not able to execute it. How do I fix this?
scannerTesting is my package and ScannerTesting.java is my main file.
D:\Java>javac Testing\src\scannerTesting\ScannerTesting.java
D:\Java>java Testing\src\scannerTesting\ScannerTesting
Exception in thread "main" java.lang.NoClassDefFoundError: Testing\src\scannerTesting\ScannerTesting <wrong name: scannerTesting/ScannerTesting>
.
.
.
java -cp ./Testing/src scannerTesting.ScannerTesting
When you run java, it looks for matching classes within its classpath. So what these arguments are doing is add your source folder to the classpath using -cp, and specify that the class that should be run is scannerTesting.ScannerTesting.
For more information, check out java cli tool documentation at Oracle
scannerTesting is your package name,right?
If so, I suggest you run command "java" under the workspace D:\Java\Testing\src
java scannerTesting.ScannerTest
I am to connect to a MySQL database from a Java application to store images taken from a scanned form. When I run the program I get a Could not find or load main class error.
I have tried setting the classpath but still get the same error: Could not find or load main class. By the way, another java file I created in the directory compiles. When I try to set the classpath I also get the same error. Here is the (EDITED)code:
java -cp "C:\Documents and Settings\xxx\Desktop\ttt_manual_yyy\mysql\mysql-connector-java-5.1.6-bin" ImageUploader C:\Documents and Settings\yyy\Desktop\IMAGES localhost uuu nnn
Where localhost is database address,uuu is username,nnn is password
You're not even specifying a class, and you need to put your classpath in quotes as it's got spaces. So it should be something like:
java -classpath "C:\Documents and Settings\...\ImageUpload" foo.ImageUploader
where foo.ImageUploader is the fully-qualified name of the class containing the main method.
When I fire the following from command line:
D:\workspace 2\project\lib>java -javaagent:myagent.jar -cp asm-all-3.3.jar;. AgentMain
I get the following error
java.lang.NullPointerException
java.lang.NullPointerException
Exception in thread "main" java.lang.NoSuchMethodError: java.lang.VerifyError: method(init) (Ljava/lang/String;) V not found
java.lang.NullPointerException
Couldnot find the main class AgentMain. Program will exit.
I have all the files and jar in the working directory. AgentMain is the compiled class that I put it here from the bin folder. I dont know what is the problem.
I would check first whether the Agent is implemented OK?
You did follow the structure as set forth in java.lang.instrument (public static void premain(String agentArgs);) including the MANIFEST entries? And there's no way that the Agent can throw NPEs during initialization?
Also, you may want to try out wheter it's the Agent or the AgentMain.class, by running java -javaagent:myagent.jar -cp asm-all-3.3.jar;. -version
Have you tried setting the classpath to the current folder (-cp . ) ?