Use eclipse to view the source code, press and hold Ctrl + left mouse button to display source not found

Problem: Query the underlying implementation method of the class when writing code, Ctrl+left mouse button, the pop-up interface shows source not found
Reason: The src.zip file in the JDK was not found in the eclipse development environment
Solution:
1. Click Window- preferences, find the installed JREs under Java,
2. Click the jre1.8.0_131 package, select Edit on the right, click to pop up the edit window

3. Select c:\program files\java\jre 1.8.0-131\lib\rt.jar Under
source attachment, click source attachment on the right

4. Select external location, select external file, import the src.zip file in the jdk package, and click OK to save.