About solving the problem of "An internal error occurred during: "Launching xx on MyEclipse Tomcat ".java.lang.NullPointerException"
"xx" is the project name
1. Close the MyEclipse workspace.
2. Then delete the file
"/.metadata/.plugins/org.eclipse.core.runtime/.settings/com.genuitec.eclipse.ast.deploy.core.prefs" under the workspace .
In this file is stored some deployment project information. There is no error after deleting the information of the deployed project.
3. Restart and start MyEclipse to solve the problem.