java eclipse red exclamation mark
The red exclamation mark usually means there is a problem with the Build Path. Do you see any alerts in the "Problem" View?
It means that there are two things happened.........
What ever jar file or project setup jar file for your application are not located at that point where it was earlier in your computer. So that First you have to setup your project with all the jar files and refresh it.
Check syntax in your project might be some mistake in that.
It means that there is an error on that project.. You can look at all the errors in the Problems tab. press ALT SHIFT Q followed by X to show this tab.