My advice: Do what you like, money cannot compensate for a life filled with drudgery. If you like Java, then by all means learn Java. If you like Perl then learn perl. I could come up with a decent argument that you really should learn Visual Basic - not Java - if money is what you are after...
IMHO a number of people here have also given you good advice: Don't focus on one language to the exclusion of all others. It is myopic to do so. I have never met a skilled programmer that did not know at least one other language fairly well. I'm not saying there aren't any but if you only have a hammer...
Remember, it is not about the language - Its about the solution.