strange behavior with Arrays.sort()

Programming Questions

Makio135

strange behavior with Arrays.sort()

in Programming Questions • 1 year ago

Hello all,

When using the Arrays.sort() function on String array b, String array a is also sorted.

Could someone explain me why?

String[] a = {
"dg","a","swdtgf","dwghf","dfddfg","vrt","aze","ccx","gt","njk","kiuylloo","b"
};
println(a);
/*
prints:
[0] "dg"
[1] "a"
[2] "swdtgf"
[3] "dwghf"
[4] "dfddfg"
[5] "vrt"
[6] "aze"
[7] "ccx"
[8] "gt"
[9] "njk"
[10] "kiuylloo"
[11] "b"
*/
String[] b=a;
println(b);
/*
prints:
[0] "dg"
[1] "a"
[2] "swdtgf"
[3] "dwghf"
[4] "dfddfg"
[5] "vrt"
[6] "aze"
[7] "ccx"
[8] "gt"
[9] "njk"
[10] "kiuylloo"
[11] "b"
*/
Arrays.sort(b);
println(a);
/*
prints:
[0] "a"
[1] "aze"
[2] "b"
[3] "ccx"
[4] "dfddfg"
[5] "dg"
[6] "dwghf"
[7] "gt"
[8] "kiuylloo"
[9] "njk"
[10] "swdtgf"
[11] "vrt"
*/
println(b);
/*
prints:
[0] "a"
[1] "aze"
[2] "b"
[3] "ccx"
[4] "dfddfg"
[5] "dg"
[6] "dwghf"
[7] "gt"
[8] "kiuylloo"
[9] "njk"
[10] "swdtgf"
[11] "vrt"
*/

http://makio.free.fr/

Replies(4)

Ale_

Re: strange behavior with Arrays.sort()

1 year ago

When you say "String[] b=a;" you aren´t copying the contents of a to b, you are pointing b to the same memory allocation than a, instead. Thus when you sort the array stored there you change both a and b...
Use arrayCopy() instead: http://processing.org/reference/arrayCopy_.html
Regards!

Ale · 60rpm.tv/i

Makio135