Replace JDK Version failed , It's still the previous version ( Two kinds of analysis 、 terms of settlement )

Scene description : I used to use JDK yes 1.8 Version of , But when the project changes, you need to use 1.7 Version of , I then downloaded and installed 1.7 Version of , The configuration of environment variables has also been changed , But when I “ ignorantly meddlesome ” stay CMD Panel command line input : What I found out after that was :
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And then I was depressed . For a long time , There's no problem with the configuration ~
Then I checked the relevant solutions on the Internet , I found that there are a lot of such situations , The reason for the problem is :

My situation is different from his , My first installation is 1.8 Of , Then switch back 1.7 Of , The same problem arises , Maybe the same solution can be used , Check out the solution

Unfortunately, I didn't find these three files in my directory , It's embarrassing, isn't it ~????, Although this method is really available for many students in the same situation , But I can't do this , Can't , And find solutions on the Internet .
Finally found , First of all, let's take a look at my :
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  • The cause of my problem :
  • therefore , The solution is

The modified :
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verification :
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Modification successful !