The JDK is successfully installed and eclipse is also successfully installed. At this time, it is actually not necessary to configure the JDK, because the system has already configured it for you by default, but the following conditions need to be configured: 1. You have multiple JDKs installed in your system; 2. Project engineering requires a higher version of JDK, etc. The
operations are as follows:
1. First run eclipse normally, open the window-preferences window that will pop up the page, enter the search jdk in the window.
2. Click Installed JREs 
as shown in the figure 3. Click Add as shown in the figure …
4. Click on Standard VM as shown in the figure
5. Find your jdk as shown in Directory
6. Check the required jdk as shown in the figure to complete. 
7. Thank you.