After clicking Preferences, click> in front of Java in the pop-up box, and click Installed JREs in Java
Click JDK in the pop-up box, click the second Eidt JRE on the right, and a box will pop up on the right:
Find …\jre\lib\rt.jar in the JRE system library in the pop-up box, click it, and then click the third item Source Attachment… on the right side, the operation is as follows:
Select External location --> External File... in the pop-up box, select the path to the root directory of JDK, find src.zip and click, the operation is as follows:
Finally save the settings: Click OK --> Finish --> Apply --> Apply and Close.
