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2012/01/18

4 tips to improve performance of Java application with database


Java database performance tips 1:
Find out how many database calls you are making and minimize those believe it or not if you see performance in seconds than in most cases culprit is database access code. since connecting todatabase requires connections to be prepared, network round trip and processing on database side, its best to avoid databasecall if you can work with cached value. even if your application has quite dynamic data having a short time cache can save many database round trip which can boost your java applicationperformance by almost 20-50% based on how many calls got reduced. 

Java database performance tips 2:
Check whether your database has indexed on columns if you are reading from database.

Java database performance tips 3:
Use PreparedStatement or Stored Procedure for executing query Prepared Statements are much faster than normal Statement object as database can pre-compile them and also cache there query plan. 

Java database performance tips 4:
Use Connection Pool for holding Database Connections. 


2012/01/17

Java Comparator Example

If you have a List of the employee objects then you need to use Collections.sort() method to sort the list holding employee objects. Below example will show how to write custom comparator. I’ve given three examples of custom comparators.

Employee Object

Next you need to define the custom comparator which will help you to sort by employee name, gender and age.

Name comparator

Gender Comparator

Age Comparator



 Here is the main class which uses the comparator to sort the employee objects based on name, gender and age.



 The default result is based your insertion order.

If you apply NameComarator

The result will be sorted based on name.

If you apply AgeComparator

The result will be sorted by age.

If you apply GenderComparator

The result will be sorted by gender

2012/01/15

5 Skills for Tech Leads

1) Development

You should be a developer, and a good one.

2) Release Management

Your main job is to resolve needs and roadblocks (not to make sure that people are following any methodology).

3) Product Management

Prioritize, that's all. Then, you just have to work on the most important tasks from your list (which will also be small ones if you did your homework). 

4) Recruiting

Learn how to test people inside your team.

5) Managing People

Be honest and helpful. 


2012/01/13

How Larry Page Changed Meetings At Google After Taking Over Last Spring



  • Every meeting must have one clear decision maker. If there's no decision maker -- or no decision to be made -- the meeting shouldn't happen.
  • No more than 10 people should attend.
  • Every person should give input, otherwise they shouldn't be there.
  • No decision should ever wait for a meeting. If a meeting absolutely has to happen before a decision should be made, then the meeting should be scheduled immediately.




Read more: 
http://www.businessinsider.com/this-is-how-larry-page-changed-meetings-at-google-after-taking-over-last-spring-2012-1#ixzz1jK8m4Hva

2012/01/12

iReport 直式/橫式報表

需求
根據User所選擇要輸出橫式或直式的格式,分別輸出符合指定格式的報表

若user選擇列印格式為橫式

就輸出橫式報表

若user選擇列印格式為直式

就輸出直式報表

作法 - 橫式報表
由於iReport建立template後,default式Portrait,此時要手動去修改其page format
1. right click --> Page Format

2. Choose "Landscape" -- > OK

3. Change sucessfully

4. Drag and drop data field to template

作法 - 直式報表
1. Drag and drop data fields into template

2. Click each data field and go to change its property

3. Change "Rotation" property to "Right"

4. Check the result



Winners and Losers in Business Open-Source Software


Application Server/Web Server:
  • Trending Up: Node.js and NGINX
  • Trending Level: Tomcat and Apache HTTP Server
  • Trending Down: JBoss and GlassFish
Frameworks:
  • Trending Up: Rails
  • Trending Level: Spring, Grails, Struts
  • Trending down: (none)
Databases and Big Data:
  • Trending Up: HBase, Hadoop, MongoDB
  • Trending Level: MySQL, PostgreSQL
  • Trending Down: CouchDB

2012/01/08

How to create barcode in iReport

Here is a simple example to create barcode in iReport

Scenario
1. As user click "Preview" in iReport, it will show dialog to input
2. iReport will generate barcode in "Preview" mode

Process
1. File-->New

 2. Choose "Blank A4"-->Open this Template

 3. Give it a name, barcodeReport, and click Next

4. Click Finish

5. Right click --> Add Parameter

6. Assign "barcodeParam" as its parameter name

7. Show palette: Window-->Palette

8. Click Barcode, Drag and Drop to template

9. Choose "Code128A" as our barcode type, and click "Use Barbecue"

10. A barcode has displayed in our template

11. Click "..." button in "Code Expression"

12. Assign "barcodeParam" in "Code Expression"

13. Click "Preview" to switch into Preview Mode

14. Input random value in this popup window and click OK

15. iReport will generate barcode based on the value you inputed

16. Download barcode reader in your smart phone, iPhone, and scan it to do validation




2012/01/03

IO Error: Size Data Unit (SDU) mismatch:oracle.net.ns.NetException: Size Data Unit (SDU) mismatch

Problem
As I would like to do query via JPA, I got this error message
IO Error: Size Data Unit (SDU) mismatch:oracle.net.ns.NetException: Size Data Unit (SDU) mismatch

Solution
This problem results from inappropriate JDBC jar file, just upgrade your JDBC jar file to 11.2.0.3.0 or above