You can import a bunch of .java files to your existing project without creating a new project. Here are the steps:
- Right-click on the Default Package in the Project Manager pane
underneath your project and choose Import
- An Import Wizard window will display. Choose File system and select the Next button
- You are now prompted to choose a file
- Simply browse your folder with .java files in it
- Select desired .java files
- Click on Finish to finish the import wizard
Check the following webpage for more information:
http://people.cs.uchicago.edu/~kaharris/10200/tutorials/eclipse/Step_04.html