Sort a list in java
Here is a nice example of sorting of a list
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package com.javagist.sort; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; /** * This program sorts a list of Strings in ascending and descending order. * * @author javagist * */ public class SortExample { private List<String> namesList = Arrays.asList("Kevin", "Brian" , "Steve", "Bill", "Obama"); public static void main(String[] args) { SortExample sortExample = new SortExample(); System.out.println("Before sorting:" + sortExample.namesList); sortExample.sortList(sortExample.namesList); System.out.println("List in ascending order:" + sortExample.namesList); sortExample.reverseSortList(sortExample.namesList); System.out.println("List in descending orde :" + sortExample.namesList); // sort a new list and don't modify the order of original list List<String> keepOriginalOrderList = Arrays.asList("Kevin", "Brian" , "Steve", "Bill", "Obama"); List<String> sortedList = sortExample.sortListWithoutModifyingOriginalList(keepOriginalOrderList); System.out.println("List has preserved order :" + keepOriginalOrderList); System.out.println("New sorted list :" + sortedList); } /** * This method makes it obvious that any object that extends comparable can be sorted. * @param list - list to be sorted */ private <E extends Comparable<E>> void sortList(List<E> list){ Collections.sort(list); } /** * This method makes it obvious that any object that extends comparable can be sorted. * @param list - list to be reverse sorted */ private <E extends Comparable<E>> void reverseSortList(List<E> list){ Collections.sort(list, Collections.reverseOrder()); } /** * This method preserves the original List ordering. And returns a new sorted list * @param list - list to be sorted but not modified */ private <E extends Comparable<E>> List<E> sortListWithoutModifyingOriginalList(List<E> list){ List<E> newList = new ArrayList<E>(list); Collections.sort(newList); return newList; } } |
References http://programtalk.com/java/sort-list-java/