Hi, How can we validate a double value with regular expression in java? For example ..if a field takes ###.### as mask .. then user can enter atmost 3 digits before the decimal and one decimal point followed by atmost 3 digits. thanks for the guidance in advance..

Karthik, Take a look at the "range" symbol for Regular Expressions. This lets you say "at least one, but not more than three digits." For more help, try posting what you have so far and we can give comments.