JSP: Get Current Date

Short snippet showing how to get current date in a JSP using scriplet code. In occasions it's needed to have the date served by the server instead of using JavaScript code, which depends of right configuration in user's machine, or differences may arise due to distinct time zones.

<%@ page import="java.util.*" %>
<%@ page import="java.text.SimpleDateFormat"%>
 
<%
   Date dNow = new Date();
   SimpleDateFormat ft = 
   new SimpleDateFormat ("MM/dd/yyyy");
   String currentDate = ft.format(dNow);
%>

<p>The current date is: <%=currentDate%></p>

Unit testing vs Integration testing

Though question if someone has to decide between the two, Unit testing and integration testing are not mutually exclusive. Both of them have their merits in the world of automating testing. In this page we will discuss the the advantages and disadvantages of each approach, and will try to provide a recommendation to apply in the Commerce site. There is a good on line article we will use as reference (see reference at bottom of this page) as it makes a good comparison of the two.

Difference in a nutshell 

The distinction between unit testing and integration testing is simple. Unit testing focus on the internal functionality of a single class, while integration testing proves functionality of an entire system, validating that all classes work fine together. In unit testing, when a class depends of another to complete an operation, it's common to use mocking technique to break the dependency and worry only about the class being tested. In integration testing all classes are real implementations and reflects the real work flows of the application.

A brief comparison

Let's compare a few aspects between the two methods. 

Driving the design

Not only in theory, but also for personal experience, we know that unit testing helps to enforce correct designed solutions in the code. Let's be honest, if you have big chunk of code in a single class method, you will find that there is no “clean” way to unit test the core logic. You will wish to go back in time and prevent yourself from writing nasty code. 

That's one reason why unit testing should be done very closely with production code. If it is pushed forward, the poor person in charge of the unit testing code will find himself having to apply refactoring, with the fear of breaking already tested approved shiny functionality. No one wants to face business explaining why application went down for applying simple tests. You can always make your QA team to regress test everything, but that makes it more expensive.

Integration testing does not improve the design, as it doesn't depend of the underlying implementations. This is a pro and con at the same time. By one hand you don't have to worry about refactoring the code just to apply testing, but it won't help improving the code which is also a good thing in terms of maintenance productivity.

Easy to write 

Unit tests are easy to write if they are done side to side with production code. It can get complicated if refactoring is required to make the code unit testable. Integration tests are easy to write in general. It can get complicated depending of the configuration required to prepare the setups required to initialize the test, and to finalize it. For example, if a user story requires interaction with a database, some initial setups will be required to leave the database in a particular state. After the test, another code will need to be run to leave the database as it was before running the test. Depending also of the framework used, coding tests in a web application context (in-container testing) can take a while to learn the first time. Once learning curve is passed, it might get easier.

Confidence in the test 

Unit testing provides a good level of confidence in the application code, but since it doesn't test integration among subsystems, it doesn't give the level of confidence an integration test provides. Integration tests are the best for regression testing. 

Fail troubleshooting 

With any type of x-unit, it will be common for a test to fail. That is the all point of the automated tests. To discover when someone screws up the application, breaking the functionality that a test is 

supposedly covering. 

Tests need to be maintained. It means that if a test fails, someone has to spend sometime figuring out what happened with the test. Why it failed? With unit testing is pretty straightforward. The test points the exact class method that failed. With integration testing you don't know at first glance what was the specific code that failed the entire operation. Therefore, it's more difficult to troubleshoot an integration test when it fails.

Documentation

Unit tests and integration tests are both good ways to document the system. Unit tests document the internal implementations. Integration tests documents user stories.

Speed

Unit tests are definitely faster than integration tests. Since integration tests can interact with databases, web services, application framework stacks, etc, they might become very slow. Usually they are not run as usual as unit tests, which are very common for developers to run to verify nothing got broken during development.

Summary Table

Here's a summary table with our rating of the different aspects commented before. This might be a little subjective as any rating system, but it provides a general overview of both methods. You can see each one has its strengths and weaknesses.

	Unit Testing	Integration Testing
Confidence in the application
Documentation
Driving the design
Easy to write
Fail Troubleshooting
Friendly with Legacy Code
Speed

Java: Converting String to Enum

Sometimes is necessary to convert a String value to an Enum, perhaps because we have the value as a String in the database, but we want to manipulate it as an Enumerator in the Java code.

The follow code shows hot to obtain the Enum value from a String. Basically, a static method is added to the Enum to return the specif Enum value. This is accomplished by iterating all the Enum values and making a comparison with the String value passed as a parameter. If the String does not match with any of the values, then an illegal argument exception is thrown.

public enum Volcano {

 IRAZU("Irazu"), POAS("Poas"), ARENAL("Arenal"), RINCON_DE_LA_VIEJA("Rincon de la vieja");

 private String name;

 private Volcano(String name) {
  this.name = name;
 }

 public static Volcano fromString(String name) {
  if (name == null) {
   throw new IllegalArgumentException();
  }
  for (Volcano volcano : values()) {
   if (name.equalsIgnoreCase(volcano.getName())) {
    return volcano;
   }
  }
  // Passed string value does not correspond to a valid enum value.
  throw new IllegalArgumentException();
 }

 public String getName() {
  return this.name;
 }

 public static void main(String[] args) {
  Volcano volcano1 = Volcano.fromString("Poas");
  System.out.println(volcano1);

  Volcano volcano2 = Volcano.fromString("rincon de la vieja");
  System.out.println(volcano2);

  Volcano volcano3 = Volcano.fromString("Fuji");
 }
}

Output:

POAS
RINCON_DE_LA_VIEJA
java.lang.IllegalArgumentException
 at com.bodybuilding.common.enums.Volcano.fromString(Volcano.java:22)
 at com.bodybuilding.common.enums.Volcano.main(Volcano.java:36)

Oracle: Search text in name of tables and columns

Just a couple of handy Oracle SQL sentences to search for a specific string contained in the name of tables and columns. I found them useful when working in maintenance for legacy systems, or big projects where you didn't start from the beginning.

To search inside name of tables, indexes, etc:

SELECT * 
FROM dba_objects 
WHERE object_name LIKE '%STRING%';

To search inside name of columns:

SELECT owner, table_name, column_name 
FROM all_tab_columns 
WHERE column_name LIKE '%COL_STRING%';

Calculate days lived since birth date

Just a small piece of code showing how to calculate total days lived since birth date (to current date):

import java.util.Calendar;
import java.util.GregorianCalendar;
 
public class TotalLifeTimeDays {
  
 public int getLifeTimeDays(int birthYear, int birthMonth, int birthDay) {
   
  Calendar birthDayCal = new GregorianCalendar();
     Calendar currentDayCal = Calendar.getInstance();
 
  birthDayCal.set(birthYear, birthMonth, birthDay);    
  return (int)((currentDayCal.getTime().getTime() - birthDayCal.getTime().getTime())
     / (1000 * 60 * 60 * 24));  
 }
  
 public static void main(String[] args) {
  TotalLifeTimeDays totalLifeTimeDays = new TotalLifeTimeDays();
  int totalDays = totalLifeTimeDays.getLifeTimeDays(1982, 11, 20);
  System.out.println("Total days lived: " + totalDays);
 }
}

Oracle: ORA-12519, TNS: no appropriate service handler found

This error can have various root causes, but in my particular case it was bothering me while trying to open new connections because apparently I had exceeded the maximum amount of processes and/or allowed sessions.

Fortunately, this value can be modified by running a simple SQL sentence (Oracle needs to be restarted after):

alter system set processes=150 scope=spfile;

SQL*Plus: Release 10.2.0.1.0 - Production on Thu Jun 27 14:46:58 2013

Copyright (c) 1982, 2005, Oracle.  All rights reserved.


Connected to:
Oracle Database 10g Express Edition Release 10.2.0.1.0 - Production

SQL> select * from v$resource_limit where resource_name in ('processes','sessions');

RESOURCE_NAME                  CURRENT_UTILIZATION MAX_UTILIZATION
------------------------------ ------------------- ---------------
INITIAL_ALLOCATION
----------------------------------------
LIMIT_VALUE
----------------------------------------
processes                                       38              40
        40
        40

sessions                                        42              49
        49
        49

RESOURCE_NAME                  CURRENT_UTILIZATION MAX_UTILIZATION
------------------------------ ------------------- ---------------
INITIAL_ALLOCATION
----------------------------------------
LIMIT_VALUE
----------------------------------------


SQL> alter system set processes=150 scope=spfile;

System altered.

SQL> exit
Disconnected from Oracle Database 10g Express Edition Release 10.2.0.1.0 - Production
gabo@gabo-Precision-M6600:/usr/lib/oracle/xe/app/oracle/product/10.2.0/server$ sudo /etc/init.d/oracle-xe restart
Shutting down Oracle Database 10g Express Edition Instance.
Stopping Oracle Net Listener.

Starting Oracle Net Listener.
Starting Oracle Database 10g Express Edition Instance.