Who can discuss with me if these answer is correct or not?

1>. What Java extensions are you fluent with and how where they used?
.java :java source file
.class :java class file
.jsp :a java server page file
.jar :when one want to pack many file into a file.

2>. What language would you use to parse a file to extract text patterns under certain conditions?
I would use java.

3>What concerns might you have about running Java classes on Solaris, Windows 2000 and Linux?
First,on windows 2000, \ is used in path while / is used in Solaris,Linux
Secondly,One should pat attention on classpath.