Can we run or develop apps for iPhone in Java?
Have a look to these links and answer:
Currently, there is no JVM running on the iPhone. This means that the only way you have to develop apps for iPhone in Java is to have a compiler that will compile your java code down to Objective-C code.
There are several solutions that do exactly that:
Codename One - focuses on building applications using Java with visual tools and simulators. Open source with a SaaS backend that removes the need for a Mac.
XMLVM - a translator to convert Java bytecode to C/Objective-C. Open source, but requires writing iOS specific code at the moment.
There are also several proprietary solutions but I have no experience with them. E.g. Software AG has a tool called web objects.