Code Generator Part VIII: The generated code

As the concluding part of the Code Generator series here is an example of how the generator works to generate the code. In this post I am going to present a sample object definition as the input (order.xml) to generate couple of Java source files using the home made code generator.

A piece of code generated using your home made Code Generator

Here is an example of an XML object specification for Customer, Order, OrderItem and Item objects to be supplied as the input for the code generation.

Order.xml

<?xml version="1.0" encoding="UTF-8"?>
<!-- order.xml -->
<OOSpec name="Order">
<Package name="">
<Class name="Customer" stereotype="class" visibility="public" baseInterfaces="Transformer">
<Import reference="java.util.Vector"/>
<Attribute name="code"/>
<Attribute name="names" multiplicity="3" defaultValue="Partha,Sarathi,Sengupta"/>
<Attribute name="age" type="integer"/>
<Attribute name="contacts" multiplicity="*"/>
<Operation constructor="yes" documentation="This is default constructor"></Operation>
<Operation directive="" documentation="This is transform operation" name="transform" returnType="string" bodyClassName="com. codegenerator.ToXMLStringBody">
</Operation>
</Class>
<Class name="Order" baseInterfaces="Transformer">
<Attribute name="number"/>
<Attribute name="date" type="date"/>
<Operation constructor="yes"></Operation>
<Operation name="transform" returnType="string" bodyClassName="com. codegenerator.ToXMLStringBody" synchronized="yes">
</Operation>
</Class>
<Class name="OrderItem" baseInterfaces="Transformer">
<Attribute name="number" type="integer"/>
<Attribute name="quantity" type="integer"/>
<Operation constructor="yes"></Operation>
<Operation name="transform" returnType="string" bodyClassName="com. codegenerator.ToXMLStringBody">
</Operation>
</Class>
<Class name="Item" documentation="This is a sample documentation">
<Attribute name="number"/>
<Attribute name="description" defaultValue="This is a description of the item"/>
<Attribute name="price" type="double" defaultValue="2.12"/>
<Operation constructor="yes"></Operation>
<Operation name="transform" returnType="string" visibility="public" bodyClassName="com.codegenerator.ToXMLStringBody">
</Operation>
</Class>
<Class name="Transformer" stereotype="interface" baseInterfaces="java.io.Serializable">
<Operation name="transform" returnType="string"></Operation>
</Class>
</Package>
<Association name="">
<Role class="Customer" multiplicity="1" name="" start="yes" navigable="no"/>
<Role class="Order" multiplicity="2" name="myOrders" navigable="yes"/>
</Association>
<Association name="">
<Role class="Order" multiplicity="1" name="order" start="yes" navigable="no"/>
<Role class="OrderItem" multiplicity="4" name="orderItems" navigable="yes"/>
</Association>
<Association name="">
<Role class="OrderItem" multiplicity="1" name="" start="yes" navigable="no"/>
<Role class="Item" multiplicity="1" name="item" navigable="yes"/>
</Association>
</OOSpec>

The Java source codes generated from the above specification are presented below. Notice how the transform method has been generated differently in each class.

Customer.java

/* This file has been generated by the CodeGenerator */
package com.order;
import java.util.Vector;

public class Customer implements Transformer {
private String code;
private String[] names;
private int age;
private java.util.ArrayList contacts;
private Order[] myOrders;

public String getCode() { return this.code; }
public void setCode(String code) { this.code = code; }
public String[] getNames() { return this.names; }
public void setNames(String[] names) { this.names = names; }
public int getAge() { return this.age; }
public void setAge(int age) {this.age = age;}
public java.util.ArrayList getContacts() {return this.contacts;}
public String getContacts(int index) {return (String)this.contacts.get(index);}
public void setContacts(java.util.ArrayList contacts) {this.contacts = contacts;}
public void addContacts(String contacts) {this.contacts.add(contacts);}
public Order[] getMyOrders() {return this.myOrders;}
public void setMyOrders(Order[] myOrders) { this.myOrders = myOrders;}
public Customer() {
code = new String();
names = new String[3];
names[0] = new String("Partha");
names[1] = new String("Sarathi");
names[2] = new String("Sengupta");
age = 0;
contacts = new java.util.ArrayList();
myOrders = new Order[2];
for(int i=0; i<myOrders.length; i++) { myOrders[i] = new Order(); }
}

/*This is transform operation*/
public String transform() {
StringBuffer sb = new StringBuffer();
if(code != null && !code.toString().equals("")) {
sb.append("<code>"+code+"</code>");
}
else {
sb.append("<code/>");
}
for(int i=0; i<names.length; i++) {
if(names[i] != null && !names[i].toString().equals("")) {
sb.append("<names>"+names[i]+"</names>");
}
Else {
sb.append("<names/>");
}
}
sb.append("<age>"+age+"</age>");

for(int i=0; i<contacts.size(); i++) {
if(contacts.get(i) != null && !contacts.get(i).toString().equals("")) {
sb.append("<contacts>"+((String)contacts.get(i)).toString()+"</contacts>");
}
Else {
sb.append("<contacts/>");
}
}
for(int i=0; i<myOrders.length; i++) {
if(myOrders[i] != null){
sb.append("<myOrders>");
sb.append(myOrders[i].transform());
sb.append("</myOrders>");
}
Else {
sb.append("<myOrders/>");
}
}
return sb.toString();
}
}

Order.java

/* This file has been generated by the CodeGenerator */

package com.order;
import java.util.*;

public class Order implements Transformer{
private String number;
private java.util.Date date;
private OrderItem[] orderItems;
public String getNumber() {return this.number;}
public void setNumber(String number) { this.number = number; }
public java.util.Date getDate() { return this.date; }
public void setDate(java.util.Date date) { this.date = date; }
public OrderItem[] getOrderItems() { return this.orderItems; }
public void setOrderItems(OrderItem[] orderItems) { this.orderItems = orderItems; }
public Order(){
number = new String();
date = new java.util.Date();
orderItems = new OrderItem[4];
for(int i=0; i<orderItems.length; i++) {
orderItems[i] = new OrderItem();
}
}
public synchronized String transform() {
StringBuffer sb = new StringBuffer();
if(number != null && !number.toString().equals("")){
sb.append("<number>"+number+"</number>");
}
else {
sb.append("<number/>");
}
if(date != null && !date.toString().equals("")) {
sb.append("<date>"+date+"</date>");
}
else {
sb.append("<date/>");
}
for(int i=0; i<orderItems.length; i++) {
if(orderItems[i] != null){
sb.append("<orderItems>");
sb.append(orderItems[i].transform());
sb.append("</orderItems>");
}
else {
sb.append("<orderItems/>");
}
}
return sb.toString();
}
}

Item.java

/* This file has been generated by the CodeGenerator */

package com.order;
import java.util.*;

/*This is a sample documentation*/
public class Item implements java.io.Serializable{
private String number;
private String description;
private double price;
public String getNumber() { return this.number; }
public void setNumber(String number) { this.number = number; }
public String getDescription() { return this.description; }
public void setDescription(String description) { this.description = description; }
public double getPrice() { return this.price; }
public void setPrice(double price) { this.price = price; }
public Item() {
number = new String();
description = new String("This is a description of the item");
price = 2.12;
}
public String transform(){
StringBuffer sb = new StringBuffer();
if(number != null && !number.toString().equals("")){
sb.append("<number>"+number+"</number>");
}
else{
sb.append("<number/>");
}
if(description != null && !description.toString().equals("")) {
sb.append("<description>"+description+"</description>");
}
else{
sb.append("<description/>");
}
sb.append("<price>"+price+"</price>");
return sb.toString();
}
}

OrderItem.java

/* This file has been generated by the CodeGenerator */

package com.order;
import java.util.*;

public class OrderItem implements Transformer{
private int number;
private int quantity;
private Item item;
public int getNumber(){ return this.number; }
public void setNumber(int number) { this.number = number; }
public int getQuantity(){ return this.quantity; }
public void setQuantity(int quantity){ this.quantity = quantity; }
public Item getItem(){ return this.item; }
public void setItem(Item item){ this.item = item; }
public OrderItem(){
number = 0;
quantity = 0;
item = new Item();
}
public String transform(){
StringBuffer sb = new StringBuffer();
sb.append("<number>"+number+"</number>");
sb.append("<quantity>"+quantity+"</quantity>");
if(item != null && !item.toString().equals("")) {
sb.append("<item>");
sb.append(item.transform());
sb.append("</item>");
}
else{
sb.append("<item/>");
}
return sb.toString();
}
}

Hope this article will help those who are looking for preliminary information on the concepts and technologies used in code generation. Please feel free to leave your comments.