CODEWITHSUNDEEP
javaprocessbuilder
gmtosh
gmtosh

Reputation: 1

Class Not Found Exception when Trying to Execute a Java Application with ProcessBuilder

I'm trying to execute the Main method within a class in a jar file by using Java's ProcessBuilder from a servlet. I need to run this in a separate process due to other dependencies.

I'm getting the following exception, so I guess that I am not correctly passing the package and Main method name (com.test.Main) in the arguments array. I am not sure how to do this correctly.

I'd appreciate any suggestions. Thanks.

ERROR -- java.lang.NoClassDefFoundError: com/test/Main ERROR -- Caused by: java.lang.ClassNotFoundException: com.test.Main ERROR -- at java.net.URLClassLoader$1.run(URLClassLoader.java:202) ERROR -- at java.security.AccessController.doPrivileged(Native Method) ERROR -- at java.net.URLClassLoader.findClass(URLClassLoader.java:190) ERROR -- at java.lang.ClassLoader.loadClass(ClassLoader.java:307) ERROR -- at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)

ERROR -- at java.lang.ClassLoader.loadClass(ClassLoader.java:248) ERROR -- Could not find the main class: com.test.Main. Program will exit. ERROR -- Exception in thread "main"

Here's my code.

    public int runProcessBuilder() throws IOException, InterruptedException{
    {
        // Get absolute path
        File dir_location = new File(".");
        String appPath = dir_location.getCanonicalPath() + "\\Tomcat 6.0\\webapps\\TestServer\\WEB-INF";

        // Args to run
        String[] argList = {"java.exe","-Djava.library.path="+appPath+"\\lib","-classpath",appPath+"\\lib\\test.jar","com.test.Main","-pTEST_ARG","123"};           

        // Create ProcessBuilder
        ProcessBuilder builder = new ProcessBuilder(argList);

        // Set Environment variable(s)
        Map<String, String> environ = builder.environment();
        environ.put("TEST_HOME", appPath);

        // Set java directory - TODO: use system property
        String java_exe = "C:\\Program Files\\Java\\jdk1.6.0_18\\bin";
        builder.directory(new File(java_exe));

        // Start Process
        final Process process = builder.start();

        // Read error stream
        StreamReader errorReader = new StreamReader(process
                .getErrorStream(), "ERROR");

        // Read input stream
        StreamReader outputReader = new StreamReader(process
                .getInputStream(), "OUTPUT");

        // Start both reader threads
        errorReader.start();
        outputReader.start();

        // Wait for process end and get Exit Code
        int exitCode = process.waitFor();
        System.out.println("Exit code: " + exitCode);

        return exitCode;
      }
}

Upvotes: 0

Views: 4177

Answers (2)

Stephen C
Stephen C

Reputation: 718718

There is something wrong with either the "-classpath" argument or the JAR file you are trying to use.

  • Print out the value of the "-classpath" argument, and check that the JAR file is really at that location in the file system, and that it is readable.

  • Use jar -tvf test.jar | grep ... to check that the Main class is in the JAR file, and has the correct path in the JAR.

(It is not the Manifest that is the issue ... because you are not using "-jar".)

(It is also not an issue with the signature of main entrypoint method ... because that would have resulted in a different exception.)

Upvotes: 1

buruzaemon
buruzaemon

Reputation: 3907

Have you set the Main-Class value in your jar's manifest file?

That would be something like:

Main-Class: com.test.Main

You might want to review the Running JAR-Packaged Software documentation.

Upvotes: 0

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