如何基于一列对一维（或二维）数组（多维）排序？

Question

I have an array of comma separated strings in an android project as follows:

1,orange,$5
2,apple,$6
3,banana,$8

I want to sort the array by a field, say by the 2nd field as apple, banana, orange...

What would be the best data structure or algorithm to handle this?

Answer 1

Sort your array with a custom comparator:

import java.util.Arrays;
import java.util.Comparator;

class Fruits {

    public static void main(final String[] args) {
        final String[][] data = new String[][] {
                new String[] { "1", "orange", "$5" },
                new String[] { "2", "apple", "$6" },
                new String[] { "3", "banana", "$8" } };

        Arrays.sort(data, new Comparator<String[]>() {
            @Override
            public int compare(final String[] entry1, final String[] entry2) {
                final String fruit1 = entry1[1];
                final String fruit2 = entry2[1];
                return fruit1.compareTo(fruit2);
            }
        });

        for (final String[] s : data) {
            System.out.println(s[0] + " - " + s[1] + " - " + s[2]);
        }
    }

}

Output:

2 - apple - $6
3 - banana - $8
1 - orange - $5

You can read more in:

http://docs.oracle.com/javase/7/docs/api/java/lang/Comparable.html

How does this comparator work?

Answer 2

You should model the String values into a java bean like let's say Fruit. In that class you need to implement the Comparable interface in which you state the manner of how objects are compared. Create your objects using the newly create class and populate your objects into a list and after that, simply call Collections.sort() and you'll have your list sorted;

Answer 3

Why don't you use ArrayList collection for your data, it is easy to sort data. You just need to implement Compralable interface in your model class and inside compareTo method write the logic of sort. Use collection.sort() to sort the data.