Eclipse + Tomcat, after modifying the code, Tomcat does not automatically update debugging

Eclipse + Tomcat Works, Tomcat is introduced into eclipse as a server, after modifying the code in Eclipse, Tomcat does not automatically update debugging, and after restarting Tomcat, the modified code does not work, Almost as if Tomcat could not load the newly modified code.

I don't know what the reason is, but it's not about eclipse and Tomcat, it's a code problem, it feels like if the code is wrong and the compilation doesn't pass, then Tomcat doesn't debug the code, at least not in the console. (In fact, the mode of the tool is a Java Virtual machine), so the premise is to get the code right, can be compiled, and the code involved in the file path can be found, that is, the Web project can run, and so on to complete these after try again.