Is there a way to get the current ‘date’ and ‘time’, modify them and use as a new input?

This is the code I am using.

time_started = new Date()
println "TEST STARTED AT (America/New_York): " + time_started.format(“yyyyMMdd-HH-mm”, TimeZone.getTimeZone(‘America/New_York’))
runtime = " "+ time_started.format(“yyyyMMddHHmm”, TimeZone.getTimeZone(‘America/New_York’))
seconds = time_started.format(“HHmmss”, TimeZone.getTimeZone(‘America/New_York’))