The Hello Android project generated by Eclipse is a fresh, clean project with no compiled binary sources. You also need to understand what happens under the hood of Eclipse at a high level. I cover this information in the next few sections.
If you were quick enough to look (or if your computer runs on the slower edge of the spectrum), you may have noticed a little red icon hovering over the Hello Android folder icon in the Package Explorer in your Eclipse window after you clicked the Finish button. If you didn't see it, you can see an example in Figure 5-6. Displaying that icon is how Eclipse lets you know that something is wrong with the project in the workspace.
By default, Eclipse is set up to let you know when an error is found within a project with this visual queue. Behind the scenes, Eclipse and the Android Development Tools are doing a few things for you:
If you don't want automatic recompilation turned on, choose Project Build ...