A needed file was deleted by mistake, and you want to restore it.
No problem. Restore the file using the container project's Restore from Local History context menu item.
To restore a deleted file, right-click the file's project, and select Restore from Local History, opening the dialog shown in Figure 2-18. In the figure, a .class file that was deleted is restored.
Figure 2-18. Restoring a deleted file
Because the Java perspective's Package Explorer doesn't display all files, including .class files, you'll need to switch to the Navigator view in the Java perspective or use the Resource perspective if you want to restore .class files.