public static void main( String[] args )
  {
    CheckingAccount account1 = new CheckingAccount( "123", "Bob", 100 );
    account1.display() ;
    account1.processDeposit( 2000 );
    account1.processCheck( 1500 );
    account1.display() ;
    
    CheckingAccount account2 = new CheckingAccount( "007", "James Bond", 50000 );
    account2.display() ;
    account2.processDeposit( 70000 );
    account2.processCheck( 10000 );
    account2.display() ;
    
  }
When the program is run, you will see:
123 Bob 100 123 Bob 585 007 James Bond 50000 007 James Bond 110000
Now try to do something a little bit tricky.
Say that James wrote out a $300 check to Bob, 
and that Bob deposited the check in Bob's account.
Add statements
(after all the others in the main method) that do this.