sorting string arrays alphabetically

[lance743]

i allready know string arrays can be sorted alphabetically using the bubble sort and other sorting methods. i was just wondering if there is a class out-there somewhere that allows this, or something that is build into java that lets me do this with ease without using the old school sorting ways...

thanks

lance

[wildfrog]

You can use the TreeSet to store your strings (in a sorted manner).

- petter

[riscoh]

Check this out:

http://java.sun.com/j2se/1.5.0/docs/...omparable.html
http://java.sun.com/j2se/1.5.0/docs/...omparator.html

[lance743]

Check this out:

http://java.sun.com/j2se/1.5.0/docs/...omparable.html
http://java.sun.com/j2se/1.5.0/docs/...omparator.html

so the compair makes your strings into a int so they can be sorted or something like that?

[Joe Nellis]

java.util.Collections.sort

[lance743]

java.util.Collections.sort

ok i got it .. here is a example..

import java.io.*;
import java.util.*;

public  class bubbleSort
{
	public static void main(String [] args)throws IOException
	{
		String [] stringArray = new String[20];
		int count = 8;

		stringArray[0] = "z";
		stringArray[1] = "d";
		stringArray[2] = "b";
		stringArray[3] = "a";
		stringArray[4] = "g";
		stringArray[5] = "m";
		stringArray[6] = "p";
		stringArray[7] = "i";
	
		sortArray(count, stringArray);

		System.out.println("---final---");
		for(int i = 0; i < count; i++)
			System.out.print(stringArray[i] + "  ");

		System.out.println();

	}


	private static void sortArray(int numberofItems,
								  String list[])
	{
		boolean exchangeMade;
		int pass = 0;
		String temp;

		exchangeMade = true;

		while((pass < numberofItems - 1) && exchangeMade == true)
		{
			exchangeMade = false;
			pass++;
			for(int index = 0; index < (numberofItems - pass); index++)
			{
				System.out.println();
				if(list[index].compareTo(list[index + 1]) > 0)
				{
					temp = list[index];
					list[index] = list[index + 1];
					list[index + 1] = temp;
					exchangeMade = true;
				}
				for(int i = 0; i < 8; i++)
					System.out.print(list[i] + " ");
				
			}
		}

	}
}

there is nothing simpler like

stringArray.sortAlpha()

or something like that?... unless i put this in a class

[wildfrog]

there is nothing simpler like

stringArray.sortAlpha()

or something like that?...

Looking at your code you don't use java.util.Collections.sort(...) at all.

- petter

[Joe Nellis]

If you read String documentation you would see it overides the Comparable interface. This implies that the String object has a natural ordering. The ordering is lexographic (alphabetical more or less). Only objects that have a 'natural ordering' can be sorted OR you can provide a an anonymouse inner Comparable class to sort however you wish, overriding the objects natural ordering. Someone or I can give an example later.

[wildfrog]

Here is an example of sorting string (in an ArrayList>

java.util.ArrayList<String> pList = new java.util.ArrayList<String>();
        
// add elements to list
pList.add("d");
pList.add("a");
pList.add("c");
pList.add("b");

// iterate through list
for (String str : pList)
    System.out.println(str);
        
// sort list
java.util.Collections.sort(pList);
        
// iterate through list
for (String str : pList)
    System.out.println(str);

- petter

[Joe Nellis]

The sort method also takes a comparator which you can specify to pull an ordering out of the list. This creates and inline implementation of the Comparator interface

// sort list
java.util.Collections.sort(pList, new Comparator<String>(){

  //override the compare method
  public int compare(String dis, String dat){
      // order by string length
      return dis.length() - dat.length();
  }

});  // note brace, paranthesis closure. This ends the sort method call.