From java.util.Collections: Collections.max() and Collections.min() Comparable<C> a = …; Comparable<C> b = …; Comparable<C> min = Collections.min(Arrays.asList(a,b)); From org.apache.commons.lang3.ObjectUtils : ObjectUtils.max() and ObjectUtils.min() Comparable<C> a = …; Comparable<C> b = …; Comparable<C> min = ObjectUtils.min(a, b); Apache Commons has less overhead and is able to handle null values, but it is a third party library.
What is logic behind ordering object elements? how “(this.grade – s.grade)” if positive 1 moves “this.grade” front and puts “s.grade” next in order, why not other way around? Using negative numbers to say “this is less than that”, positive numbers to say “this is more than that” and 0 to say “these 2 things are … Read more
Comparable doesn’t allow null simply because: a.compareTo(b) == -b.compareTo(a) for all objects a and b where !a.equals(b). More specifically: a.equals(b) ? b.equals(a) && a.compareTo(b) == 0 && b.compareTo(a) == 0 && a.hashCode() == b.hashCode() : !b.equals(a) && a.compareTo(b) != 0 && a.compareTo(b) == -b.compareTo(a) must evaluate to true to satisfy the relevant contracts. So null … Read more
To make classes comparable, you only need to implement __lt__ and decorate the class with functools.total_ordering. You should also provide an __eq__ method if possible. This provides the rest of the comparison operators so you don’t have to write any of them yourself.
Essentially, you’re asking if there’s a way to tell the compiler, “hey, this one method requires the type parameter match more specific bounds than defined at the class level“. This is not possible in Java. Such a feature may be useful but I’d also expect confusing and/or complicated. There’s also no way to make Stream.sorted() … Read more
You can use the until function in the Kotlin stdlib: for (i in 1 until 5) { println(i) } Which will print: 1 2 3 4
Guava is more elegant: return ComparisonChain.start() .compare(d1.weight, d2.weight) .compare(d1.age, d2.age) .compare(d1.name, d2.name) .result(); Apache commons-lang has a similar construct, CompareToBuilder.
Added to Comparator in Java 8: static <T extends Comparable<? super T>> Comparator<T> naturalOrder() Use it like this, for example: Comparator<Double> natural = Comparator.<Double>naturalOrder(); return natural.compare(1.0, 1.1));
This should work for all classes that extend Number, and are Comparable to themselves. By adding the & Comparable you allow to remove all the type checks and provides runtime type checks and error throwing for free when compared to Sarmun answer. class NumberComparator<T extends Number & Comparable> implements Comparator<T> { public int compare( T … Read more
Official Definition From the reference docs of Comparable.compareTo(T): Compares this object with the specified object for order. Returns a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object. The implementor must ensure sgn(x.compareTo(y)) == -sgn(y.compareTo(x)) for all x and y. (This implies that … Read more