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Book Review : Learning Ext JS 4

The folks at Packt asked me to review another of their book on Learning EXTJS 4 If you are interested in buying it (a judgment you may reserve until after you have read the review)EXTJS4 is on packt site
this is link you can go.Learning EXtJs 4 is on packt site

Crysfel Villa ,Armando Gonzalez are author of this book.Crysfel Villa is a Software Engineer with more than 7 years of experience with JavaScript on a daily basis.Armando Gonzalez is a Software Engineer with more than 4 years of experience
in developing enterprise applications with Ext JS. He has plenty of experience in
server-side technologies like PHP, Java J2EE, Node JS, and ROR.

The first thing you will probably notice is the size of the document. This is no brief summary of the new features. This is small book of over 40 pages covering to learn a new java script librart with a full index in the back. The structure of the book is:
Business overview

Step 1 – The Basics
Step 2 – The Core Concepts
Step 3 – Components and Layouts
Step 4 – It’s All About the Data
Step 5 – Buttons and Toolbars
Step 6 – Doing it with Forms
Step 7 –Give me the Grid
Step 8 – Architecture
Step 9 – DataViews and Templates
Step 10- The Tree Panel
Step 11 – Drag and Drop
Step 12 – Look and Feel
Step 13- From Drawing to Charting

I like this structure as it parallels the steps one would take in setting up a EXTJS 4. To add a bit of a flow to the book, they also put it in the examples,real life scenarios.

Its more a starter book.This book focuses on giving the reader a firm understanding of the core concepts of EXTJS, such as Drag and Drop and tree panel, and works through real-life app development scenarios. All core components of EXTJS’s amazing library are covered in detail, and strategies are outlined for getting the best use of time when developing with EXTJS.

Few components which i like to mention , which i enjoy reading alot – a clear explanation of how to make drag drop using EXTJS.
How tree panel compoenent work.How you can make charts components for example pie,bar , gauage. Skinning of application is well defined.

OVer all i can say this book for beginner.Few new features which is added in EXT JS 4 is added and describe well.A must purchase for those who want to learn EXT JS 4. You can also download the code which is available with the book

Happy coding with Techartifact and packt….

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Remove duplicate entries in a Vector in java

One of the solution which normally every java developer faced once.We have to remove the duplicate
value from a vector in java.

There are two solution for it one.

1.

Vector newVect = new Vector(new LinkedHashSet(originalVect));

or this, if you do not need a new Vector object created

2

Collection noDup = new LinkedHashSet(vectorContainingDup);
vectorContainingDup.clear();
vectorContainingDup.addAll(noDup);

In both cases we puting duplicate vector in linkedHashSet , which will remove the duplicate values.

Enjoy coding 🙂 with techartifact………………………….

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Performance measures in Pl/Sql

Cases should be avoided –1. DO NOT use FUNCTIONS (,TO_NUMBER ,Decode,NVL, TO_CHAR) unnecessarily when a simple join would work
2. DO NOT use ‘SELECT *’ explicitly. Make sure that you select only required columns from the tables.
3. DO NOT use HAVING clause where a WHERE clause would do.
4. DO NOT use ORDER BY clause in a query unless necessarily by logic.
5. DO NOT use UNION and DISTINCT together in a single query
6. DO NOT use CURSOR LOOPS unnecessarily when a simple/single DML/SELECT can serve the purpose
7. DO NOT use DUAL table unnecessarily in programs and queries.

Cases should be followed –
1. Use UNION ALL as far as possible instead of UNION.
2. Use single/direct DML’s/SELECT’s instead of LOOP’s.
3. Use BULK COLLECT & FORALL for looping when the loop is going to get executed multiple time (take > 100 iterations as a base).
4. Use MATERIALIZED VIEWS or GLOBAL TEMPORARY TABLE for queries fetching data across dblinks
5. Use EXISTS in place of IN in the queries.
6. Care should be taken to use the LIMIT clause while using BULK operations in order to limit memory utilization. LIMIT should be set between 500-1000 and reduced or decreased as per performance behavior of the program

References – http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14261/tuning.htm#i48876
http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/design.htm#i29012

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