MWLUG2014 AD107 First Java App Tips

MWLUG 2014

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.

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


You Are HereWhere to Begin?


Why Java? XPages is built on Java SSJS is converted to Java Futureproofs YOUR skill set Syntax is not that different from LotusScript

‘LotusScriptDim strName As StringstrName = “Schwinn”

//JavaString 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, charClass (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

CartItemCartItemCartItemCartItemCartItem


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 addCartItempublic 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 errorError 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 #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

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

http://docs.oracle.com/javase/6/docs/api/







http://www.notesin9.com/

http://www.opentf.org/

http://collaborationtoday.info/

http://collaborationtoday.info/

http://stackoverflow.com/

http://www.howtoprgramwithjava.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/

http://frostillic.us/



http://nathanfreeman.wordpress.com/



http://www.intec.co.uk/author/paulwithers/




http://www.qtzar.com/

http://www.qtzar.com/

http://www.timtripcony.com/blog.nsf









“You’re On Your Way”



Thank You!Graham AcresBlog - http://grahamacres.wordpress.com/Twitter - @gacres99Email - [email protected]

Mike McGarelBlog - http://www.bleedyellow.com/blogs/McGarelGramming/Twitter - @mmcgarelEmail - [email protected]

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MWLUG2014 AD107 First Java App Tips