Analysis

What do we need to think about?

Examples of durations

• \(43.27 \mu s\)

• \(10^9\) years

• 525,600 minutes

• 3 days, 6 hours, 17 minutes, and 25 seconds

Object-oriented analysis

What might we do with them?

• Convert units: 10 minutes = 600 seconds

• Format: 257 seconds as 4:17 or 0:04:17

• Add: 2:45 plus 3:30 is 6:15

• Subtract: 5 hours minus 2 hours is 3 hours

• Decompose: 7868 as 2 hours, 11 minutes, and 8 seconds

• Compare durations for equality and ordering

Assumptions

Some simplifying assumptions:

• Minimum time resolution: seconds

• Lower bound: 0

• Upper bound: unspecified

• Unitless: 180 seconds is equal to 3 minutes

Observers

long inSeconds();

String asHms();

int compareTo(Duration other);

boolean equals(Object other);

int hashCode();

Operations

void add(Duration other);
void sub(Duration other);

Operations

Duration plus(Duration other);
Duration minus(Duration other);

(We'll just do plus.)

Representation

Let's discuss.