Steps:-

1. Go to Project Explorer.

2. Right-click on the project, then go to properties 

3. Go to Save Actions in the Java Editor.

4. Click on Configure Workspace Settings.

5. Click on Organize Imports.

6. Select Java, then click on the Edit button

7. Write Java.util, then click on the Packages button

8. Select Java.util

9.Click on the OK ==> OK ==> Apply ==> Ok ==> Ok

10. Now you can import java.util.List packages in Eclipse.