Java example to get current user name on windows OS.
CSharp example to check current user is admin or not using dotnet framework classes.
Java class to extend java.util.Date class to add some methods given in c# like addSeconds, addMinutes, addDays, addYears etc. This are really helpful.
Java example for calculating difference between two date in different units. You can use this utility class in you java program.
Java, when you should override equals and hashCode methods. Example of overriding equals and hashCode in Java.