TreeSet should output in ascii order?

[Nigel Shrin]

This is a Whizlabs example to prove the output sort sequence of a TreeSet. It outputs: "JSP Java Swing XML" - the explanation is that this is ascii value order, but its not! XML(241) and should come after JSP(237). It looks like a letter by letter ascii comparison rather than a total ascii value, is that right?

Whizlabs test program:

public class Q12_TreeSet_ascii_order {
	public static void main(String[] args) {
		Collection<String> set=new TreeSet<String>();
		set.add("Java");
		set.add("XML");
		set.add("Swing");
		set.add("JSP");
		set.add("Java");
		for(Object o : set)
		{
			System.out.print(o + " ");
		}
	}
}

To prove it programmatically (because I need practice on collections):

import java.util.*;
public class Q12b_TreeSet_ascii_order {
	public static void main(String[] args) {
		Collection<String> tset=new TreeSet<String>();
		LinkedHashMap<Integer, String> lhm = new LinkedHashMap<Integer, String>();
		String str[]={"AAA","Java","XML","Swing","JSP","Java"};
		for(String s : str)
		{
			int j=0;
			for(int i=0;i<s.length();i++)
			{
				j+=(int)s.charAt(i);
				 System.out.println("s.charAt(i)=" + s.charAt(i) + "\ti=" + i + "\tj=" + j);
			}
				System.out.println(" ascii total for " + s + "\t =" + j + "\n"); 	
		tset.add(s);	
		// store results of ascii figures in LinkedHashMap
		lhm.put(j, s);
		}
		System.out.println("\nLinkedHashMap output, to prove ascii ordering of TreeSet:");
		for(int int1 : lhm.keySet())
		{
			System.out.println(int1 + ": " + lhm.get(int1));
		}
		System.out.println("\nTreeSet output:");
		for(Object o : tset)
		{
			System.out.println(o + " ");
		}
	}
}

This outputs:
LinkedHashMap output, to prove ascii ordering of TreeSet:
195: AAA
386: Java
241: XML
520: Swing
237: JSP

Second question:
The LinkedHashMap output is in key input sequence, how can I output it in key sequence, in this case by numeric magnitude?

Thank you!

[Henry Wong]

Nigel Shrin wrote:This is a Whizlabs example to prove the output sort sequence of a TreeSet. It outputs: "JSP Java Swing XML" - the explanation is that this is ascii value order, but its not! XML(241) and should come after JSP(237). It looks like a letter by letter ascii comparison rather than a total ascii value, is that right?

While I agree that maybe the wording could be clearer, I have to say to whizlabs defense, that no-one ever takes a sum of all the ASCII characters to determine order. Sorting by the sum of the ascii values is pretty useless, and just not done.

Henry

[Nigel Shrin]

Thank you Henry

[Prithvi Sehgal]

Hi,

Henry is absolutely correct. Great insight Henry.

Best Regards,