Comparator
but specialized to compare 32-bit
integers passed to its compare(double,double)
using primitive types (double
instead of Double
).
The method descriptions were copied, with slight modifications, from
those in Comparator
as the intention is to provide
a similar interface.
The reason for providing this class is that Java does not allow one
to use a primitive type as a type parameter:
Comparator<double>
will generate a compile-time error,
although Comparator<Double>
can be used in some cases
due to autoboxing.
- See Also:
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Method Summary
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Method Details
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compare
int compare(double o1, double o2) Compares its two arguments for order. Returns a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.In the foregoing description, the notation sgn(expression) designates the mathematical signum function, which is defined to return one of -1, 0, or 1 according to whether the value of expression is negative, zero or positive.
The implementor must ensure that sgn(compare(x, y)) == -sgn(compare(y, x)) for all x and y. (This implies that compare(x, y) must throw an exception if and only if compare(y, x) throws an exception.)
The implementor must also ensure that the relation is transitive: ((compare(x, y)>0) && (compare(y, z)>0)) implies compare(x, z)>0.
Finally, the implementor must ensure that compare(x, y)==0 implies that sgn(compare(x, z))==sgn(compare(y, z)) for all z.
It is generally the case, but not strictly required that (compare(x, y)==0) == (x.equals(y)). Generally speaking, any comparator that violates this condition should clearly indicate this fact. The recommended language is "Note: this comparator imposes orderings that are inconsistent with equals."
- Parameters:
o1
- the first double to be compared.o2
- the second double to be compared.- Returns:
- a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.
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equals
Indicates whether some other object is "equal to" this comparator. This method must obey the general contract ofObject.equals(Object)
. Additionally, this method can return true only if the specified object is also a comparator and it imposes the same ordering as this comparator. Thus,comp1.equals(comp2)
implies that sgn(comp1.compare(o1, o2))==sgn(comp2.compare(o1, o2)) for every object reference o1 and o2.Note that it is always safe not to override Object.equals(Object). However, overriding this method may, in some cases, improve performance by allowing programs to determine that two distinct comparators impose the same order.
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