I’m currently working on a project in a software testing competition. Within a period of time, I will publish a series of blogs to record my problems. My environment is under the official website of Mutest. I don’t understand the content of the test very well, so many places may not be written correctly. I hope you can correct me if you see it.
This blog records the following problem, which is how I solved it. 
Copy the tools in the lib in the jdk file directory to the lib in the jre directory, and then restart your eclipse.
My classmate also encountered the same problem, and then he went to do other things and came back to do it again. The problem was solved...confused.