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Collections sort statement not being accepted

Armando Moncada
Ranch Hand

Joined: Nov 14, 2011
Posts: 30

The Eclipse editor won't accept the line where I am trying to sort the array list using my custom comparator. (It is the second to the list line of code). Eclipse says
The method sort(List<T>, Comparator<? super T>) in the type Collections is not applicable for the arguments (ArrayList<String>, SortNames.CelebrityNamesFile.CompareLastName).

The purpose of the program is to read names from a text file, add them to an array list, sort the array list in natural order, then print it, sort the arraylist by last name, then print it again.

I have read the pertinent chapters in Just Java, Ivor Horton's Beginning Java 7, Head First Java, Googled, StartPaged, and Binged the internet for examples but I still don't know what it wants.


Armando
Henry Wong
author
Sheriff

Joined: Sep 28, 2004
Posts: 18896
    
  40

First take the error ...

The method sort(List<T>, Comparator<? super T>) in the type Collections is not applicable for the arguments (ArrayList<String>, SortNames.CelebrityNamesFile.CompareLastName).


then try to prove the compiler wrong, by finding a type for T that will work.

Henry


Books: Java Threads, 3rd Edition, Jini in a Nutshell, and Java Gems (contributor)
 
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