Before, Tomcat startup always reported errors. Although it does not affect the startup and operation of the project, programmers with obsessive-compulsive disorder will be unhappy:

The problem is caused by the inconsistency between the JDK version installed locally and the JDK version used in Tomcat

Later, I changed the jdk1.7 used in the original Tomcat startup environment to the JDK1.8 installed locally, so I won’t report an error

Specific process: in MyEclipse, click window → preference → enter Tomcat in the search box → select the installed Tomcat version. Here, I select Tomcat 7. X → click JDK → in Tomcat 7. X   JDK Name: select the JDK version installed in this machine from the drop-down option → click OK, and then start Tomcat again to avoid any error