error is coming because of wrong inner class instantiation
Correct Code would be
Note the instatnitation code of m1, m2 and m3 object. Class Man is innner class to SortMe class. Rest of your code is fine.
You can read below mentioned link for more details about instantiation code syntax
http://download.oracle.com/javase/tutorial/java/javaOO/nested.html
If you move class Man out of SortMe class (as shown in below code) then your previous code within main method of SortMe would work fine
Output of this code is
[javaapplication1.Man@19821f, javaapplication1.Man@addbf1, javaapplication1.Man@42e816]
[javaapplication1.Man@addbf1, javaapplication1.Man@42e816, javaapplication1.Man@19821f]
Hope I have cleared your doubt
Just a note that you can override toString() method of Man class to get better display of ArrayList contents (man objects)