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Start your free trialDylan Cascio
5,488 PointsWhy does `"Apple".compareTo("apple");` return -32 and not 1, 0 or -1?
As the title says "Apple".compareTo("apple");
returns -32
. Similarly, "apple".compareTo("Apple");
returns 32
.
Why is this different from the described return values of 1
, 0
, and -1
?
For reference, "APPLE".compareTo("apple"):
returns -32
and "apple".compareTo("APPLE");
also returns 32
.
1 Answer
Tonnie Fanadez
UX Design Techdegree Graduate 22,796 PointsHello Dylan Cascio
Good Question.
The compareTo()method defines the natural order - the default way for ordering objects of a class. The comparison is based on the Unicode Value of each character in the Strings being compared.
Please refer to this link for Unicode Character Table - http://sticksandstones.kstrom.com/appen.html
You will note that the Unicode value for "a" is 097 and "A" is 065 .... "b" is 98 and "B" is 66. and so forth. Since compareTo() is subtracts one value from another, the difference between a Capital Letter and a Lowercase Letter is always -32 for the same letter. The difference is always +32 for (Lowercase - Uppercase) when dealing with the same letter.
It is not a must for 1 or -1 to be returned - unless the letters being tested follow each other in case of "a" and "b" or "c" and "d" or "y" and "z"- Java documentation don't specify it is 1 or -1 to be returned but rather says a positive or a negative integer. 0 is only returned if objects are equal e.g. "d"=="d"
Hope this helps.
Cheers
Dylan Cascio
5,488 PointsDylan Cascio
5,488 PointsThank you! That's so much clearer now. I see now that I just hadn't written out enough examples in jshell. It looks like even something like
"apple".compareTo("orange");
evaluates to -14 and"apple".compareTo("czzzzzzz");
returns -2.Tonnie Fanadez
UX Design Techdegree Graduate 22,796 PointsTonnie Fanadez
UX Design Techdegree Graduate 22,796 PointsHi Dylan Cascio , glad this helped. Continue practicing on JShell, I find it very helpful for testing and learning