Yesterday I was watching a lynda.com iphone development video and this developer started telling about how he has worked on 17 different languages from the days of mainframes in assembly/Cobol to now on iPhone Objective-C. My question is how do these developers keep shifting to new technology, without fearing the loss of experience they already have about a particular technology. I am trying to shift to Java from PHP and market considers this as non-relevant experience. How do these guys do it without losing the pay and not being considered a fresher in a particular technology.