/CS121-Lab6

Primary LanguageJava

class TimeInterval

Fetch the project from GitHub at

https://github.com/paulbuis/CS121-Lab6.git

class TimeInterval is in src/main/java/cs121/TimeInterval.java. This is the only file you should modify!

Some preliminary testing is done in class TimeIntervalDemo found in TimeIntervalDemo.java in the same directory. You should not modify it, but you should run the main() found there to see if class TimeInterval is working correctly.

There are 3 problems with `class TimeInterval:

The .toString() method

As given, this method obviously is not satisfactory. Note, however, there is a method in this class with the signature

public static String formatDate(Date date)

that outputs the year, month, and day followed by hours, minutes, seconds, and milliseconds followed by the time zone offset from Greenwich Mean Time. like:

2022-02-17T10:18:44.245-05:00

If your computer has its time zone set correctly, note that Indiana in winter is 5 hours behind Greenwich.

We want the TimeIterval.toString() method to produce output that looks like:

[2022-02-17T10:18:44.245-05:00 to 2022-02-17T10:18:45.251-05:00]

Note that this starts with a [, has a to in the middle and ends with a ].

The .equals() method

Note that ti1, ti2, and ti3 should all be distinct objects (the == operator returns false when comparing them). However, ti2.equals(ti3) returns false, but should not.

Note that the TimeInterval.equals() method uses the == operator to compare Date objects when it really should use the Date.equals() method.

TimeInterval.TimeInterval(Date, Date)`

This constructor has a subtle bug. Note that near the end of the output from TimeIntervalDemo.main() there are some negative durations being output.

The problem is that when main() modifies the value of its local variable start it causes changes to the data member called start in ti1 and ti2 since the constructor caused them all to be aliases that refer to the same object.

What you need to do is have the constructor make copies of the Date objects used as parameters so the data members of TimeInterval are copies rather than aliases. The TimeInterval method with the signature

private static Date copy(Date date)

will make a copy of a Date object for you.

Completion

Run TimeIntervalDemo.main() to verify that the output looks good:

  • TimeIntervals are printing out as specified above.
  • bad is not being printed out for checks of .equals().
  • No negative durations occur at the end.