How do I sort items of an ArrayList?
Date: 2010-09-16. Category: java.util examples. Hits: 122K time(s).
This example shows you how we can sort items of an ArrayList using the Collections.sort() method. Beside accepting the list object to be sorted we can also pass a Comparator implementation to define the sorting behavior such as sorting in descending or ascending order.
package org.kodejava.example.util;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
public class ArrayListSortExample {
public static void main(String[] args) {
/*
* Create a collections of colours
*/
List colours = new ArrayList();
colours.add("red");
colours.add("green");
colours.add("blue");
colours.add("yellow");
colours.add("cyan");
colours.add("white");
colours.add("black");
/*
* We can sort items of a list using the Collections.sort() method.
* We can also reverse the order of the sorting by passing the
* Collections.reverseOrder() comparator.
*/
Collections.sort(colours);
System.out.println(Arrays.toString(colours.toArray()));
Collections.sort(colours, Collections.reverseOrder());
System.out.println(Arrays.toString(colours.toArray()));
}
}
The code will output:
[black, blue, cyan, green, red, white, yellow] [yellow, white, red, green, cyan, blue, black]