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Index › Programming Questions & Help › Syntax Questions › sorting an array of objects
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sorting an array of objects (Read 1511 times)
treon
sorting an array of objects
May 9th, 2008, 7:06am  
i've got an array of objects with 3 variables: posX, posY and distance
how do i sort the array with ascending distance?

i tried using the arrays.sort() but it always gives me this error which i have no idea what it is

java.lang.ClassCastException: Temporary_198_139$OneMinute
at java.util.Arrays.mergeSort(Arrays.java:1156)
at java.util.Arrays.sort(Arrays.java:1080)
at Temporary_198_139.SortMinutes(Temporary_198_139.java:104)
at Temporary_198_139.AssignPosition(Temporary_198_139.java:95)
at Temporary_198_139.draw(Temporary_198_139.java:42)
at processing.core.PApplet.handleDisplay(PApplet.java:1465)
at processing.core.PGraphics.requestDisplay(PGraphics.java:690)
at processing.core.PApplet.run(PApplet.java:1562)
at java.lang.Thread.run(Thread.java:613)

at java.util.Arrays.mergeSort(Arrays.java:1156)
at java.util.Arrays.sort(Arrays.java:1080)
at Temporary_198_139.SortMinutes(Temporary_198_139.java:104)
at Temporary_198_139.AssignPosition(Temporary_198_139.java:95)
at Temporary_198_139.draw(Temporary_198_139.java:42)
at processing.core.PApplet.handleDisplay(PApplet.java:1465)
at processing.core.PGraphics.requestDisplay(PGraphics.java:690)
at processing.core.PApplet.run(PApplet.java:1562)
at java.lang.Thread.run(Thread.java:613)
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JohnG
Re: sorting an array of objects
Reply #1 - May 9th, 2008, 9:31am  
arrays.sort() only knows how to sort objects that implement the Comparable interface. Otherwise how on earth will it know how to sort them?

See http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Comparable.html
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bene
Re: sorting an array of objects
Reply #2 - May 15th, 2008, 8:53am  
check this post for the Comparator thing:
http://processing.org/discourse/yabb_beta/YaBB.cgi?board=Syntax;action=display;num=1210524369;start=0
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polymonkey
Re: sorting an array of objects
Reply #3 - May 15th, 2008, 9:06am  
Warning this is a VERY dirty hack.

But you could take the fields of the array and create a String array with the field that you want to sort by at the start of the String. Sort the String array. and then you take the String array split it and move the new values back into the array of objects.

Again I'm sorry. I know it's a very crap way of doing it but it will work.

MattD
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MattD(polymonkey)
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