classpath

问题 is there any reason why to favor using (possibly very long) CLASSPATH variable to set which jars should be on classpath durign application run then to use the java 1.5+ property -Djava.ext.dirs which specifies whole directory(directories) of jars to be searched? To make it real-life example I have standalone java application with lib folder containig all dependent jars. Sofar the start script is setting all the (maybe 20) jars to CLASSPATH variable one by one. Since now my application archive

问题 Does anyone have code to detect duplicate JARs in the classpath? Background: When there are two versions of the same JAR in the classpath, really strange things can happen. This can even happen when using tools like Maven: Change a dependency and build the WAR without cleaning first. Since target/webapp/WEB-INF/lib wasn't cleaned, the dependency will be in there twice. Is there a safety-net for this? 回答1: JBoss Tattletale might help you with this. It's a free tool which scans the JAR files

问题 When I copy mysql jdbc driver to JDK's\jre\lib\ext, it execute perfectly well. Now, I want to use the jdbc by specifying its classpath to environment variable. But, after doing so, my program throws exception : "java.sql.SQLException: No suitable driver found for jdbc:mysql://localhost/books" How do I set the classpath? 回答1: You should not be putting ANY JARs in the jre/lib/ext folder. You set the CLASSPATH using the -classpath option on javac.exe when you compile and java.exe when you run.

问题 When I copy mysql jdbc driver to JDK's\jre\lib\ext, it execute perfectly well. Now, I want to use the jdbc by specifying its classpath to environment variable. But, after doing so, my program throws exception : "java.sql.SQLException: No suitable driver found for jdbc:mysql://localhost/books" How do I set the classpath? 回答1: You should not be putting ANY JARs in the jre/lib/ext folder. You set the CLASSPATH using the -classpath option on javac.exe when you compile and java.exe when you run.

问题 I wrote a console application helloworld.java and ran javac helloworld.java ,and then java helloworld . This worked fine. I then created a package com.abc.project and moved helloworld.java into it(the package import statement is correctly generated which is package com.abc.project; ). And then i ran javac helloworld.java this worked also fine and generated the class properly. However, when I ran java com.abc.project.helloworld from the console, it threw an "class not found" error. Please can

问题 I'm trying to make a "clean maven" setup on some legacy project that uses ant scripts. I don't know much about ant, so my question might seem naive. I'm almost done, but the delivery ant script is failing, due to a redundancy in the classpath. If I understand the build, those lines should add to the classpath every lib in the "provided" scope : <artifact:dependencies pathid="dependency.classpath" scopes="provided"> <pom file="./pom.xml"/> </artifact:dependencies> And then this one : <path id=

问题 All, My classpath has been set to the following folder: CLASSPATH = .;C:\Program Files\Java\jdk1.6.0_21\bin;C:\Program Files\Java\jdk1.6.0_21\bin\project All my java files and class files are under project folder listed in CLASSPATH . Yet I am getting the following error while running a DriverClass in project folder: C:\Program Files\Java\jdk1.6.0_21\bin\project>java DriverClass Exception in thread "main" java.lang.NoClassDefFoundError: DriverClass (wrong name: project/DriverClass) at java

问题 Is it necessary or important to set a class path in the registry for RMI to work correctly? 回答1: Contrary to @Rahul's baseless assertion, it is indeed necessary to set a CLASSPATH for the RMI Registry, unless: You are starting the Registry from a directory which is also the head of a package structure of .class files. You are using the codebase feature, or You are starting the Registry in the same JVM as your RMI remote obects, via LocateRegistry.createRegistry(). If you don't do one of these

问题 Hey guys im trying to connect to my remote mysql database and my code gives me this error: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver 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 java.lang.Class

问题 I've been trying to run a jar file - let's call it test.jar - that uses the Sybase jconn3.jar on a Unix system. I have created a MANIFEST.MF file that has the following: Class-Path: $SYBASE/jConnect-6_0/classes/jconn3.jar commons-net-1.3.0.jar This gives a ClassNotFoundError. $SYBASE is the system variable that points to /opt/sybase13; I've also tried the following: Class-Path: /opt/sybase13/jConnect-6_0/classes/jconn3.jar commons-net-1.3.0.jar and Class-Path: opt/sybase13/jConnect-6_0