MWLUG2014 AD107 First Java App Tips

AD107: Don’t Put the Cart Before the
Source: Tips for Building Your First
XPages Java Application
Graham Acres, President, Brytek Systems Inc.
Mike McGarel, Collaborative Solutions Developer,
Czarnowski Display Services, Inc.
MWLUG 2014

AD107: Don’t Put the Cart . . .
Graham Acres
 IBM Lotus Notes Developer/Designer
since v2.1
 Brytek is an IBM Business Partner based
in Vancouver, Canada
 Currently focus on application
development (Social Business, XPages,
Mobile)
 OpenNTF Contributor
 Away from work
Cyclist, Ride to Conquer Cancer

Mike McGarel
 Collaborative Solutions Developer at
Czarnowski Display Services
Working with Notes/Domino since version 4.6
Working on the Web for over 14 years
 OpenNTF Contributor
 Maintain MWLUG site

Disclaimer
We are
Professionals, but
NOT Experts (in
this case anyway)
 This advice is
likely not Best
Practices, but it is
our experience in
learning Java

Midwest Biking Inc.

Agenda
 Where to Begin
 Planning Your Application
 Shopping Cart Demo
 Let’s Look at the Code
 Lessons Learned and Cool Tips
 OpenNTF Domino API
 Resources
 Questions

Where to Begin? You Are Here

Why Java?
 XPages is built on Java
 SSJS is converted to Java
 Futureproofs YOUR skill set
 Syntax is not that different from LotusScript
‘LotusScript
Dim strName As String
strName = “Schwinn”
//Java
String strName = “Schwinn”;

“I Don’t Know What I Don’t Know”

“Checking the Roadmap”
Websites galore!
 Blog posts
 Notes in 9 videos
 Books
 Colleagues
 Java APIs
 Conference sessions

Java “Rules of the Road”
 Case sensitive
 Mandatory semicolon;
 XPages version is Java 6
 Data types: Primitive vs. Class (double <> Double)
Primitive (lower case), e.g., double, int, char
Class (proper case), e.g., Double, Integer, String

Don’t “Reinvent the Bicycle Wheel”
 Example: String class has 72 methods!

Collections
 You will almost always use collections whenever you
interact with a database
 LotusScript has them, e.g., NotesDocumentCollection,
ViewEntryCollection
 Java has many more, e.g., ArrayList, Vector, HashMap,
TreeMap, LinkedHashSet, TreeSet
 List – stores index position
 Map – has a key-value pairing
 Set – no duplicates

“Planning your route”

Application Design
 Front end UI
 Functionality
 Back end structure
 Client-side code
 Server-side code

Java Class Design
 Java classes needed
 Order
 Shopping cart
 Cart item
 Optional
 Utility
 Catalog
Order
ShoppingCart
CCaartrIttIetemm CCaartrIttIetemm CartItem

Class Elements
 Properties
 Often tied to form or document fields, e.g.,
 unit price for a cart item
 if the cart contains items
 Methods
 Standard getters / setters
 Custom, e.g., calculate cost (quantity x price)

Java Beans (a canned explanation)
A Java object defined by specific standards
 Public Java class
 Serializable
 Private properties (optional)
 Public constructor with no arguments
 Public methods

Sample Bean (outside)
package com.mbi.shopping;
import java.io.Serializable;
/* other possible libraries */
public class Sample implements Serializable {
private static final long serialVersionUID = 1L;
private String myText;
public Sample() {
}
public String getMyText() {
return myText;
}
public void setMyText (String txt) {
this.myText = txt;
}
}

Sample Bean (inside)
package com.mbi.shopping;
import java.io.Serializable;
/* other possible libraries */
public class Sample implements Serializable {
private static final long serialVersionUID = 1L;
private String myText;
public Sample() {
}
public String getMyText() {
return myText;
}
public void setMyText (String txt) {
this.myText = txt;
}
}

Shopping Cart Demo

ShoppingCart Class
 Properties:
private LinkedHashMap<String,CartItem> cart;
private BigDecimal totalCost;
Why a LinkedHashMap ?
 Keeps the insertion order
 Uses a key,value structure
 The key can be used on other parts of the page,
e.g., "Add to Cart" button rendering

LinkedHashMap Class Methods
 .containsKey()
 .get()
 .isEmpty()
 .put(K key, V value)
 .size()
 .values()

XPage Code for “Add to Cart” Button
<xp:button value="Add to Cart" id="btnAddToCart">
<xp:this.rendered>
<![CDATA[#{javascript:var productId = productEntry.getColumnValues()[0];
!Order.containsKey(productId)}]]>
</xp:this.rendered>
<xp:eventHandler event="onclick" submit="true” refreshMode="partial"
refreshId="content">
<xp:this.action>
<![CDATA[#{javascript:var id = productEntry.getColumnValues()[0];
var name = productEntry.getColumnValues()[1];
var price =
new java.math.BigDecimal(productEntry.getColumnValues()[4].toString());
var qty = new java.lang.Double(1);
Order.addCartItem(name,id,price,qty)}]]>
</xp:this.action>
</xp:eventHandler>
</xp:button>

ShoppingCart Class Code for addCartItem
public ShoppingCart() {
this.cart = new LinkedHashMap<String,CartItem>();
totalCost = new BigDecimal(0);
}
public void addCartItem (String name, String id,
BigDecimal price, Double quantity) {
try {
CartItem cartItem = new CartItem();
cartItem.load(name,id,price,quantity);
cart.put(id,cartItem);
calcTotalCost();
} catch (Exception ex) {
ex.printStackTrace();
}
}

CartItem Class Properties
Contains only what’s needed for processing, e.g.,
Name, ID, price, quantity, cost:
private String itemName;
private String itemId;
private BigDecimal itemPrice;
private Double itemQuantity;
private BigDecimal itemCost;

CartItem Class Methods
Mostly getters / setters, e.g.,
public Double getItemQuantity() {
return itemQuantity;
}
public void setItemQuantity (Double qty) {
this.itemQuantity = qty;
}

CartItem Loading Method
In ShoppingCart Class:
CartItem cartItem = new CartItem();
cartItem.load(name,id,price,quantity);
cart.put(id,cartItem);
In CartItem Class:
public void load (String name, String id,
BigDecimal price, Double quantity) {
setItemName(name);
setItemId(id);
setItemPrice(price);
setItemQuantity(quantity);
setItemCost(calcItemCost(quantity));
}

Order Class
 Managed bean
 Instantly available
 Loaded in faces-config.xml file
Tip: available in 9.0.1 through Domino
Designer without Package Explorer.
Preferences > Domino Designer >
Application Navigator > Application
Configuration > Faces-config

Faces-config.xml Sample
<?xml version="1.0" encoding="UTF-8"?>
<faces-config>
<managed-bean>
<managed-bean-name>Order</managed-bean-name>
<managed-bean-class>com.mbi.shopping.Order
</managed-bean-class>
<managed-bean-scope>session</managed-bean-scope>
</managed-bean>


</faces-config>

Order Class Properties and Methods
 Contains ShoppingCart property
Wrapped methods for easier access, e.g.,
private ShoppingCart cart;
public Order() {
this.cart = new ShoppingCart();
}
public void addCartItem (String name, String id, BigDecimal price,
Double quantity) {
this.cart.addCartItem(name,id,price,quantity);
}
public void removeCartItem (String key) {
this.cart.removeCartItem(key);
}

Lessons Learned and Cool Tips

Lesson Learned #1 – Number Field
 Number value becomes JavaScript number
(thanks to JSF number converter)
 Equivalent to Java Double (the class not the primitive)
 Originally used Integer class for the item quantity
Integer or int reference results in type mismatch error
Error not showing up using System.out.println
Error display control worked, because problem was
on the XPage itself

Lesson Learned #2 – Date Fields
 Java Calendar object

Lesson Learned #2 – Date Fields

Lesson Learned #3 – Try / Catch Blocks
 Error management
 Different from LotusScript
 Not just errors

Cool Tip #1 – To Do Reminder
 Add to your Java code for a handy reminder
Written as: TODO in any comment line

OpenNTF Domino API
 What is it?
 Should you use it?
 Pros / Cons
 http://www.openntf.org/main.nsf/project.xsp?r=project/OpenNTF%20Domino%20API
 https://github.com/OpenNTF/org.openntf.domino/commits/M4.5

Resources: Tutorials and Books
 Tutorial on Collections
http://docs.oracle.com/javase/tutorial/collections/interfaces/index.html
 Head First Java

Resources: Websites
 Java 6 API
http://docs.oracle.com/javase/6/docs/api/
 Notes in 9
http://www.notesin9.com
 OpenNTF
http://www.opentf.org
 Collaboration Today
http://collaborationtoday.info
 StackOverflow
http://stackoverflow.com
 How to Program With Java
http://www.howtoprogramwithjava.com

Resources: Community Blogs
 Jesse Gallagher
https://frostillic.us
 Nathan Freeman
http://nathanfreeman.wordpress.com
 Paul Withers
http://www.intec.co.uk/author/paulwithers/
 Declan Lynch
http://www.qtzar.com
 Tim Tripcony
http://www.timtripcony.com/blog.nsf
 Niklas Heidloff
http://heidloff.net/

“You’re On Your Way”

Thank You!
Graham Acres
Blog - http://grahamacres.wordpress.com/
Twitter - @gacres99
Email - graham.acres@brytek.ca
Mike McGarel
Blog - http://www.bleedyellow.com/blogs/McGarelGramming/
Twitter - @mmcgarel
Email - mcgarelgramming@gmail.com

MWLUG2014 AD107 First Java App Tips

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