Java time subtraction and countdown

Question

Am creating a desktop app for my school using netbeans and am trying to get a countdown by subtracting the time now from the a given time constant to find the number of hours in between and use it as a countdown... Please if you have any answers i would be grateful

Answer 1

One of many possible ways is to use java.time (requires at least java 8)
Follow the link in the code for other options.
https://code.sololearn.com/c7So18dz1GiH/?ref=app