Implement a class Range to present a range of elements having natural order.
To create a Range instance, simply give it a lowerbound and a upperbound. A Range can be used to check if it contains a value.
- Develop the
Rangeclass from level to level. - Tests must be added in
RangeTest.java. - All tests in
RangeTestMUST pass.
class Range {
public static Range of(int lowerbound, int upperbound);
public boolean contains(int value);
public int lowerbound();
public int upperbound();
}Class Range can be used with int.
Range validAgesForWatchingPorn = Range.of(13, 100);
validAgesForWatchingPorn.contains(5); // false
validAgesForWatchingPorn.contains(13); // true
validAgesForWatchingPorn.contains(22); // true
validAgesForWatchingPorn.contains(100); // true
validAgesForWatchingPorn.contains(101); // false
Rangemust be immutable. Once created, there is no way to change itslowerboundandupperbound.Rangemust provide a static factory method namelyof(int, int)to create a new instance.- It is not allowed to create a
Rangewithlowerbound > upperbound. - The method
contains(x)must returnstrueonly iflowerbound <= x <=upperbound.
Mathmatically, a Range can be open, closed, openClosed or closedOpen.
// open range excludes both bounds
// 4..5(..6..)7..8..9..10
// ^^^^^
(5, 7)
// closed range includes both bounds
// 4..[5..6..7]..8..9..10
// ^^^^^^^^^
[5, 7]
// open closed excludes lowerbound but includes upperbound
// 4..5(..6..7]..8..9..10
// ^^^^^^^^
(5, 7]
// closed open includes lowerbound but excludes upperbound
// 4..[5..6..)7..8..9..10
// ^^^^^^^
[5, 7)
- Extend
Rangesuch that it can support all of the above types. (This implies the methodof(int,int) will be renamed toclosed(int, it))
Range open = Range.open(5, 7);
open.contains(5); //false
Range closed = Range.closed(5, 7);
closed.contains(5); // true
Range openClosed = Range.openClosed(5, 7);
openClosed.contains(5); // false
openClosed.contains(7); // true
Range closedOpen = Range.closedOpen(5, 7);
closedOpen.contains(5); // true;
closedOpen.contains(7); // false;
Extends the Range such that it can supports any types implementing Comparable interface.
The Comparable interface is implemented by several Java types (i.e String, )
Range<String> text = Range.open("abc", "xyz");
Range<BigDecimal> decimals = Range.open(BigDecimal.valueOf("1.32432"), BigDecimal.valueOf("1.324323423423423423423"));
Range<LocalDate> dates = Range.closed(LocalDate.of(2016, Month.SEPTEMBER, 11), LocalDate.of(2017, Month.JUNE, 30)));
We want to have Range to support an open-ended style with Infinitive. For example:
Range<Integer> lessThanFive = Range.lessThan(5); // [Infinitive, 5)
lessThanFive.contains(5); // false;
lessThanFive.contains(-9000); // true;
Range<Integer> atLeastFive = Range.atLeast(5); // [5, Infinitive]
atLeastFive.contains(5); // true;
atLeastFive.contains(4); // false;
Range<Integer> atMostFive = Range.atMost(5); // [Infinitive, 5]
atMostFive.contains(5); // true
atMostFive.contains(-234234); // true;
atMostFive.contains(6); // false;
Range<LocalDate> afterEpoch = Range.greaterThan(LocalDate.of(1900, Month.JANUARY, 1)); // (1900-01-01, Infinitive]
afterEpoch.contains(LocalDate.of(2016, Month.JULY, 28)); // true;
afterEpoch.contains(LocalDate.of(1750, Month.JANUARY, 1)); // false;
Range<String> all = Range.all(); // [Infinitive, Infinitive]
all.contains("anything"); // true;
all.contains(""); // true;
all.contains(null); // true;
Implement toString() method for class Range. The toString() should represent the type and the bounds of the current Range instance.
Range<Integer> lessThen100 = Range.lessThen(100);
assert lessThen100.toString() == "[Infinitive, 100)"
Range<LocalDate> within2020 = Range.closed(
LocalDate.of(1, JANUARY, 2020),
LocalDate.of(31, DECEMBER, 2020)
)
assert within2020 == "[2020-01-01, 2020-12-31]"It is possible to create a new Range using the result from Range#toString().
This level tests your API design skills so we won't provide much information here. Please decide the signature of parse yourself.
String rangeString = Range.lessThen(100).toString();
Range<Integer> lessThen100 = Range.parse(rangeString, ...);
assert lessThen100.toString() == "[Infinitive, 100)"v2020.11.20
- Add level 6.
- Rename levels to reflect its true intent.
- Added visualization of types of Ranges.
v2020.06.01
- Initial
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