Recently I had to write a program to sort data (String) in a table and was looking for an efficient and easiest way to do sorting in java. I found two options – one was to write my own sorting program, and the other was to use the Comparator class in the Util package. I found that using Comparator or Comparable interface was very easy compared to writing my own sorting algorithm.
If you are new to using “Comparator”, I highly recommend reading this one page tutorial.
http://java.sun.com/docs/books/tutorial/collections/interfaces/order.html
Here is a working example for sorting a two dimensional string array:
import java.util.Arrays;
import java.util.Comparator;
public class Sort {
public static void main(String args[]){
//Array with address to sort
String[][] addressArray = new String[][]{
{"E","abc st","Sunshine", "FL"},
{"S","abc st","Sunrise", "FL"},
{"E","abd st","Cleveland", "OH"},
{"N","aab st","Dallas", "TX"},
{"W","xyz st","San Antonio", "TX"}};
//Sort the array by city name or column 3
Arrays.sort(addressArray, new ColumnComparator(2));
//Print the sorted array
for(int i=0; i<addressArray.length; i++){
String[] row = addressArray[i];
for(int j=0; j<row.length; j++) {
System.out.print(row[j] + " | ");
}
System.out.print("\n");
}
}
}
//Class that extends Comparator
class ColumnComparator implements Comparator {
int columnToSort;
ColumnComparator(int columnToSort) {
this.columnToSort = columnToSort;
}
//overriding compare method
public int compare(Object o1, Object o2) {
String[] row1 = (String[]) o1;
String[] row2 = (String[]) o2;
//compare the columns to sort
return row1[columnToSort].compareTo(row2[columnToSort]);
}
}
Results – sorted by city name
E | abd st | Cleveland | OH |
N | aab st | Dallas | TX |
W | xyz st | San Antonio | TX |
S | abc st | Sunrise | FL |
E | abc st | Sunshine | FL |
