J2ee common errors (available for future reference)

FAQs and solutions
Unable to start J2EE Server
Name Directory service port conflict
Symptom: when you use-verbose to start a J2EE Server, the following information is displayed:
J2EE server listen port: 1050 RuntimeException: cocould not initialize server...
Solution: Other programs use port 1050. If the J2EE service is already running, you can enter j2ee-stop to stop the service. If other programs use this port, you can modify the default port (1050) by modifying the config/orb. properties file installed in your J2EE SDK ).
For more information about the default port number, see The Configuration Wizard provided when the J2EE SDK is downloaded.
Web service port conflict
Symptom: when you use the-verbose option to start the J2EE service, the following information is displayed:
LifecycleException: HttpConnector [8000]. open:
Java.net. BindException: Address in use...
Solution: Other programs use port 8000. You can modify the default port (8000) by modifying the config/orb. properties file installed by your J2EE SDK ).
Incorrect XML parsing
Symptom: when you use the-verbose option to start the J2EE service, the following information is displayed:
Exception in thread "main"
Javax. xml. parsers. FactoryConfigurationError:
Org. apache. xerces. jaxp. SAXParserFactoryImpl...
Solution: delete the jre/lib/jaxp. properties file from your J2SE installation directory.
Compilation error
Ant cannot find the constructor file
Symptom: After you enter ant converter, the following information is displayed:
Buildfile: build. xml does not exist!
Build failed.
Solution: go to the j2eetutorial/examples/src directory before running ant. If you want to run ant in the current directory, you must specify the construction file in the command line. For example, you need to enter the following command in the same line in the window:
Ant-buildfile C: j2eetutorialexamplessrcuild. xml
Converter
The compiler cannot parse symbols.
Symptom: After you enter ant converter, the compiler reports many errors, including:
Cannot resolve symbol
...
BUILD FAILED
...
Compile failed, messages shoshould have been provided
Solution: Make sure that you have correctly configured the J2EE_HOME environment variable. For more information, see check environment variables.