Das Ostern is finished and finally, I’ve been assigned to a project. As you know, sometimes it takes a few days to prepare environment, setup all accounts, and so on. Thus, during the last two days my schedule is pretty much relaxed and I can spend some time for self-education – I am reading the Servlet 3.0 specification, writing some simple application in order to try discovered features, and wondering about two things: how really cool servlet 3.0 is and how I could missed it?! If you did not touch it as well, take a look on the following briefly Read the rest of this entry »
During the last three months I have been working as a developer for a consulting android project. It is actually my first commercial experience (I do not count written demo examples at my previous work) and I found it extremely interesting, though a quite confusing at some moments.
The following article describes an observed problem with the facebook key hashes for the android application. To describe the problem and its solution, let’s define a simple use case.
Read the rest of this entry »
The following code snippet shows how to restart an android application after the specified delay programmatically:
public void restart(int delay) {
PendingIntent intent = PendingIntent.getActivity(this.getBaseContext(), 0, new Intent(getIntent()), getIntent().getFlags());
AlarmManager manager = (AlarmManager) this.getSystemService(Context.ALARM_SERVICE);
manager.set(AlarmManager.RTC, System.currentTimeMillis() + delay, intent);
System.exit(2);
}
Related API:
PendingIntent
AlarmManager
The following code snippet shows how to minimize the current application in android programmatically:
Intent main = new Intent(Intent.ACTION_MAIN);
main.addCategory(Intent.CATEGORY_HOME);
main.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(main);
Related API:
Activity
Finally, I did it. About a month I have passed the java certification exam and it was not that hard as I expected. A brief story how it was.
Firstly, let me give a few cents about the exam preparation. The rule is really simple: if you have a few years (or even not a few) of the experience with Java and you believe that you do no need to read any books and you are by now ready to take it – forget about it, you will most likely fail, because of the specific exam pitfalls. Take a week or two and play with the exam preparation materials.
Read the rest of this entry »
Easy as ABC, you may answer, and you will be absolutely right! It is not rocket science, yet some code looks quite complicated to complete this simplest task.
Today I watched a new episode of the Bones tv show and browsed some open source code. I found the following method:
public int getCount(Class clazz) {
Integer rowCount = new Integer(0);
Criteria criteria = getCurrentSession().createCriteria(SomeEntity.class);
List results = criteria.list();
if(results != null && !results.isEmpty()){
rowCount = results.size();
} else {
rowCount = new Integer(0);
}
return rowCount;
}
Okay, 11 “readable” lines of code so far. Read the rest of this entry »
A few months ago, I wrote an article how to map the one-to-one bi-directional relations between two entities and now is the time for a simple example how to map many-to-many relation. You can find what Many-to-Many relation means in Wikipedia, and the following article only shows how it looks like in Db and how it can be mapped in Hibernate. Ready? Read the rest of this entry »
Are you working with Java? Have you ever seen the following warning message:
Type safety: The expression of type List needs unchecked conversion to conform to List<SomeClass>
I’ve seen it a lot. Technically, there is nothing wrong with this warning in most cases. The warning is related to API that either was built to support Java versions less than 1.5 or is a bit clumsy. Anyway, I do not really like any warnings in my code so I can’t ignore it. How to remove this warning? Read the rest of this entry »
If you ever see how the JSR 303 validation works, you probably know how awesome this way is. I like it because it makes the code more readable, easy to maintain and to add new features. Additional information about the approach is available here, and in this article, I am going to show how to test JSR 303. Read the rest of this entry »
In the following article, I would like to show an approach how to map one-to-one bi-directionall two entities in Hibernate.
First of all, let’s take a look at the relation between two tables in a database:
As you can see, there is the one-to-one relation between user and user_profile tables and the user_profile table has a primary key that in fact, it is a foreign key to the id property of the user table. In other words, there is a simple use-case: one user record can have only one related user_profile record.
What the mapping looks like?
There are two classes. Read the rest of this entry »
