Custom Sort - Apex

ComparableDemo.apxc

/**************************************************************
Class : ComparableDemo
Purpose: To sort by custom field/variable in Wrapper class, in following case- CreatedDate
Example: //Sample Apex code be executed in Anonymous window
List<ComparableDemo> lCD = new List<ComparableDemo>();
List<Account> lAcct = [select id, createdDate from Account order by lastModifiedDate desc];
for(Account a: lAcct)
{
    lCD.add(new ComparableDemo(a));
}
lCD.sort();
for(ComparableDemo oC:lCD)
System.debug(oC.acct.ID + ' || ' + oC.acct.CreatedDate);
****************************************************************/
public class ComparableDemo implements Comparable
{
    public Account acct; 
    public ComparableDemo(Account a){
        this.acct =a;
    }
    
    public Integer compareTo(Object compareTo) {
        ComparableDemo cd = (ComparableDemo)compareTo;
        Account compareToAcct = cd.acct;
        
        //If both are equal
        if(compareToAcct.get('CreatedDate') == acct.get('CreatedDate'))	return 0;
        
        //IF:my current account i.e. the one declared above is small, then return -1(so that it will be ascending)
        if(compareToAcct.CreatedDate > acct.CreatedDate)	return -1;
        
        return 1;
    }

}