198 Lotus blogs updated hourly. Who will post next? Home | Blogs | Search | About 
 
Latest 7 Posts
Go Evergreen
Tue, Oct 17th 2017 32
Change is in the Air
Fri, Sep 1st 2017 1
Open Source Contribution
Fri, Jun 16th 2017 4
Docker Quick Tips
Fri, Apr 28th 2017 2
Notes in 9: Dev Tools Grab Bg
Tue, Apr 4th 2017 2
Custom JSON Serialization With GSON
Mon, Jan 23rd 2017 5
Recapping 2016
Mon, Jan 16th 2017 5
Top 10
Go Evergreen
Tue, Oct 17th 2017 32
Building Java Objects From JSON
Thu, Jan 22nd 2015 10
Server REST Consumption with Authentication
Mon, Aug 18th 2014 8
Headless DDE Builds With Jenkins CI
Fri, Mar 25th 2016 8
MWLUG Success
Wed, Aug 24th 2016 7
When You Need a Comparator
Thu, Jan 8th 2015 6
When You Need a Comparator
Fri, Jan 9th 2015 6
Notes in 9: Docker + SonarQube
Wed, Feb 24th 2016 6
SCM Survey Results
Tue, Apr 12th 2016 6
Using Node to Connect to ... Almost Anything
Mon, Apr 18th 2016 6


When You Need a Comparator
Twitter Google+ Facebook LinkedIn Addthis Email Gmail Flipboard Reddit Tumblr WhatsApp StumbleUpon Yammer Evernote Delicious
   

Introduction

Many of the XPages Managed Bean demonstrations point to your ability to populate an xp:comboBox with a custom defined List of Select Items. One thing that seems to happen to me is that I wind up having to re-sort such lists to work off of their Label, as opposed to their value; so as to look sorted, at least to human eyes.

A Brief ComboBox Anatomy Lesson

An xp:comboBox lets us build out a list (preferably somewhat short) of values with their labels, which are selected from a “drop down” like interface. More specifically, from MDN,

The HTML select (<select>) element represents a control that presents a menu of options. The options within the menu are represented by <option> elements, which can be grouped by <optgroup> elements. Options can be pre-selected for the user.

But you’re here for the code. Here’s an incredibly simple select tag implemented with three options. If you switch to the HTML pane, you’ll see that the value (which is what can be data bound for value in the xp:comboBox control) is 1, 2, or 3 while the labels are their English equivalent of One, Two, or Three. In classic Notes, we would achieve this by the usual list (line separated) by passing in sets of Label | Value, separated by the pipe character. You can still do this in XPages, but if you’re defining the source for one in a bean, you’ll want to build out your List. My sample class below shows this, but the meat and potatoes here is the Comparator.

A Comparator

Enter java.util.Comparator. It’s a member of the Collections Framework, making it ideal for sorting Collections (which a List is). So, to begin, we’ll define a class (you can nest it in another class, as I have, a stand-alone class, or a member of another, utility class. This class contains a single, public compare method, which returns an int. It returns an int, as that’s what’s returned by the compareToIgnoreCase method of java.lang.String. All the compare method is doing is comparing whether the first string is before or after the second string.

Code

Here’s my super simple sample bean, with the selectOptionsList being read-only (no setter method) as it’s just the selectedOption being what the value to be stored is.


The XPage control implementation is a standard xp:comboBox implemented with the value and select items (options) bound via EL. The value which the user selects is bound to the bean’s property of selectedOption while the list of SelectItems (options list, with both value and labels populated) is the selectOptionsList property.


Here’s the full gist link, with class, XPage, and faces-config (in case anyone is looking for how my bean is registered).



---------------------
https://edm00se.github.io/DevBlog/xpages/when-you-need-a-comparator
Jan 08, 2015
7 hits



Recent Blog Posts
32
Go Evergreen
Tue, Oct 17th 2017 4:00p   Eric McCormick
Happy 🎂 Day IE 11! On the 17th of October in 2013, Internet Explorer 11 was released from Microsoft. That means that as of today, this popular* browser is now four years old and, with all respect to it, it really ought to go. Good day sir. I said good day! Evergreen Browsers What makes a browser, or any software for that matter, evergreen? Well, the basic requirements for a browser, or any piece of software for that matter, are specifically the support of automatic updates, that bring in:
1
Change is in the Air
Fri, Sep 1st 2017 1:00p   Eric McCormick
I’m Back What Can I Say? In Case You Missed It If you find yourself asking “where was Eric?”, this should summarize it all: Instead of trying to do everything all summer, I tend to take a break from blogging and a lot of open source endeavors over the summer. It means I can focus on family time along with yard and house projects. Ah... Summer That’s all paid off and, with fall fast approaching, I’ve found myself wanting to start those things back up; ramping up into winter when
4
Open Source Contribution
Fri, Jun 16th 2017 5:00p   Eric McCormick
Intro It’s time to clear some of the backlog. I started this post a few months back and it should probably be sent on its way to clear the pile of drafts I haven’t finished yet… 🤔 I have a bit of a passion for open source software. My preferred distribution of Linux has been Ubuntu since 4.10, the Warty Warthog (I was even a minor contributor on a short lived, wildly popular project that aimed at improving the Ubuntu experience early on), I’ve enjoyed most open source projects I’ve
2
Docker Quick Tips
Fri, Apr 28th 2017 3:00p   Eric McCormick
Docker If you have been living under a rock, Docker is pretty much amazing. If you haven’t been living under a rock, you may be getting used to the idea of Docker, but still have the occasional question. I’ve found myself using Docker in increasing amounts and complexity over the last year or so. I’ve recently decided to start recording some of the tasks I’ve found useful, some of which may be less familiar to a beginner. If you’re so inclined, check out the playlist, embedded here.
2
Notes in 9: Dev Tools Grab Bg
Tue, Apr 4th 2017 1:00p   Eric McCormick
Intro I’m on Notes in 9 again, with a “grab bag” of a couple of tools I’ve put together recently that may be of a varying degree of useful for other Domino + XPages developers. You don’t need these to do development, but for the right person, they may help with their development workflow. Also of note, with the upgrade to Swiper with the FP8 release of Notes + Domino Designer, the limitations previously mentioned are no longer there! This means that my second tool I talked about, node-
5
Custom JSON Serialization With GSON
Mon, Jan 23rd 2017 2:00p   Eric McCormick
Intro Here’s a curious one, in which I found myself with a limitation of not being able to output JSON with scientific notation values. wait, what? If you’re wondering why that is, since both JSON and JavaScript allow scientific notation of number values, you are absolutely correct and that’s a great question. The strange thing was that I found myself outputting perfectly valid JSON to be consumed by something specific which didn’t allow scientific notation. I’m not entirely sure wh
5
Recapping 2016
Mon, Jan 16th 2017 3:00p   Eric McCormick
Intro Per usual, I’ve had a little break between things and decided to catch up with a bit of a summary of some recent things that each didn’t necessitate their own post. 2017 IBM Champion For starters, I’m honored to be named an IBM Champion in Collaboration Solutions (/ Social Business) for the third time. This would be a hat trick in (ice) hockey 🏒. I’m happy to be recognized with a group of people, developers and more, who are passionate about both their work and the plat
6
Rebirth: An App of Ice and Fire
Wed, Dec 14th 2016 4:00p   Eric McCormick
Intro If you read my blog for any of the Saga of Servlets series, then I hope that you’re excited I’m returning to the application I put together for it. This time, it’s as a conversation piece in regards to some of the build process modernization I engaged in recently, in order to unify the code base in its git repository. In any case, it’s helping pave the way forward before I update some of the back-end elements, when it will again be a talking point for some additional rework and
3
Scripting Server Upgrades
Fri, Nov 11th 2016 2:00p   Eric McCormick
Intro This one might be slight departure from my usual, but those that have followed my blogging this past year will have noticed a bit more of a leaning towards DevOps in some of my posts. This echoes a lot of what I’ve been concluding as increasingly a necessary part of development; that we need to consider a picture large enough to encompass the themes surrounding development functions and, like any good developer (DRY ~= “lazy”), automate the heck out of it. Overview I had p
4
Everything Old is New Again
Mon, Oct 24th 2016 8:00p   Eric McCormick
Intro Every so often, it’s good to reassess one’s position. This is good from both a standpoint of being inquisitive and even interrogative, but when it comes to the ever changing landscape of the front-end development space, it’s not only inevitable, but must be embraced for what feels the need to “stay afloat”. I’m changing theme of my blog, hopefully for the better. The previous theme was good and did a great job of getting things started, but while I had forked a copy of a good




Created and Maintained by Yancy Lent - About - Planet Lotus Blog - Advertising - Mobile Edition