Section 12.12. Resources

12.12. Resources

Kent Beck and Ward Cunningham, "A Laboratory for Teaching Object-Oriented Thinking", in OOPSLA'89 Conference Proceedings, New Orleans, Louisiana, October 16, 1989. The special issue of SIGPLAN Notices 24, no. 10 (October 1989) is also available online at http://c2.com/doc/oopsla89/paper.html#cards.

More on the Capability Maturity Model can be found at http://www.sei.cmu.edu/cmm/.

Information on the Unified Modeling Language can be found at http://www.uml.org/.

Example 12.1. The Account class

 package net.multitool.core; import net.multitool.util.*; import java.util.*; import java.sql.*; public class Account {   private String name;                      // A name to identify this account   private User owner;                       // The user assigned to this account   private SAMoney total;                    // Total amt originally allocated to                                             //   this account   private SAMoney balance;                  // amt remaining unallocated to any                                             //   subaccounts   private Account parent;                   // The account which contains this                                             //   account as a child   private HashMap children;                 // The collection of subaccounts,                                             //   by name   private static Connection dbConn = null;  // JDBC connection   private ArrayList payments;               // TODO: unimplemented   private SAMoney unspent;                  // TODO: unimplemented   /**    * Create an account, with a pool of dollars to budget.    * Use this constructor to create the master account.    * Use createSub to create children of this account.    */   public   Account(String name, User owner, String total)     throws NumberFormatException   {     this.name = name;     this.owner = owner;     this.total = new SAMoney(Double.valueOf(total).doubleValue());     this.balance = new SAMoney(Double.valueOf(total).doubleValue());                                                // N.B. must not be the same object     this.parent = null;     this.children = new HashMap();   }   // Static that connects to the DB and either returns the top account,   // or creates it for us.   public static Account getTopAccount() throws SQLException {   Account topAccount = null;   dbConn = DriverManager.getConnection("jdbc:postgresql:budgetPro?user=mschwarz");   if (dbConn != null) {     // We have a database connection.   } else {     // We don't and we must create a top account.   }   return topAccount;   }   // Simple getter; returns the name.   public String   getName() { return name; }   // Simple getter; returns the total pool of money that this account represents.   public SAMoney   getTotal() { return total; }   // Simple getter; returns the balance.   public SAMoney   getBalance() { return balance; }   // Simple getter; returns the parent account.   public Account   getParent() { return parent; }   // Simple getter; returns the owner of this account, as a User object.   public User   getOwner() { return owner; }   // Census - how many children.   public int   size() { return children.size(); }   /**    * Get to all the children, via an iterator.    */   public Iterator   getAllSubs()   {     return children.values().iterator();   }   /**    * Create a new subaccount (i.e., child)    * given a name and an amount.    * The child is connected to the parent, and    * the parent's balance is reduced by the amount    * allocated to the child.    */   public Account   createSub(String name, String amt)     throws NumberFormatException   {     Account acct = new Account(name, owner, amt);     // Reduce the parent's unallocated funds.     balance = balance.subtract(acct.getTotal());     // Connect the accounts to each other.     acct.parent = this;     children.put(name, acct);     return acct;   } // createSub   /**    * Looks up and returns the account with the given name.    */   public Account   getSub(String name)   {     return (Account) children.get(name);   } // getSub } // class Accoun 

The Umbrello UML modeller is an Open Source tool for creating the various UML diagrams. You can find it at http://uml.sourceforge.net/index.php. We also recommend their online documentation as a good brief introduction to UML and to Umbrello. It can be found from the main Umbrello page, or directly at http://docs.kde.org/en/HEAD/kdesdk/umbrello/.