I have a question why eclipse is preferred professionally over netbeans for java enterprise application development, inspite of the fact that Netbeans has a better user interface and is more user friendly than eclipse ???
Who said that? The IDE to use is mainly based on your preference. Of course, if you are in a corporate environment, then you will be stuck using the IDE that the rest of the team has decided to use. Then there are numerous reasons as to why an organization would have picked one over the other. In many case it is usually because that what they always used and they have been using Eclipse since version 1.
Which IDE has a better UI or is more user-friendly is a matter of personal preference, and is not worth arguing over here. It is my experience, though, that Eclipse is indeed much more widely used wherever people have a choice in the matter. Just taking a look at jobs offered and jobs wanted ads (not in these forums, but in general) seems to bear that out.
Eclipse was created by IBM. In the ranks of old-line corporations, those three letters carry a lot of weight. I've been told that back in the 1960's, a common term for what's now know as the IT department was "IBM Department". Before there was Microsoft, IBM was basically Alpha and Omega for what they called "Data Processing". PHB's relied on their IBM rep to take care of tedious chores like thinking. When they had a problem, IBM told them what to do.
IBM open-sourced the Eclipse IDE back around 2001. It was a major-league IDE even then, and now it was free, which wasn't the case for most of the competition.
Eclipse is also more than just a Java IDE. Unlike most of its competitors, Eclipse is a general-purpose framework, and not even specifically an IDE - although the various Java IDE versions of it are the most popular. It's also capable of serving as an application framework, and as development platform for non-Java languages such as C/C++, Python, Perl, and shell scripting. I've used Eclipse plugins for all of these at one time or other. None of the preceding is a primary reason why companies pick Eclipse, but it is something that intelligent decision makers take into consideration.
NetBeans has a somewhat different history. Although it's a good product, it has been through a number of major evolutionary stages and name changes. Its major advantages are that since it was a production from the very people who invented Java (Sun), it should in theory anticipate improvements to Java and support Java-specific features. To a certain degree, it does, although Sun could have done more, especially when it came to JavaBean development and JSF WSYWIG design, which are 2 aspects where NetBeans does have an edge on Eclipse to begin with. Because NetBeans doesn't attempt to be all things to all people, it does tend to provide better support for "grunt" development, whereas Eclipse is more my cup of tea, since I'm more prone to develop systems with multiple components interacting in complex ways and non-Java components.
None of the major IDEs is really all that bad, and each has its own particular set of virtues. To a certain degree, it's just a matter of figuring out which horse you want to place your bet on. As the saying goes, "Nothing succeeds like success", and Eclipse has been successful for a very long time now.
An IDE is no substitute for an Intelligent Developer.
With most discussions about this topic many comments are based on history. Eclipse has been around for a long time and has evolved to cover many languages and professionally needed software development tools (ie. interfaces to defect databases, task-ers,...). Netbeans (not as knowledgeable in) has had a lesser evolution. [The difference being big-many-corporate contributions versus a community with a corporate sponsor.]
Things have changed over the last three years. Both Eclipse and Netbeans have evolved technically and are great for the developer. However, little sideline changes in licensing (lic.) and user agreements (UA) have impact. (Often ignored by many.)
As a professional, I adhere to the agreements when I've accepted them. As a result of changes to some of the lic. or UAs I've moved from Eclipse to Netbeans.
On the whole I've found little difference in usage for development. However, how things maybe licensed or distributed from the use of these "free" IDEs is affected. Thus, a move to Netbeans over Eclipse as the latters UA require the projects development to be opened sourced.
I've nothing against open source and do contribute. But I'd wonder about a government (trying to save $$s) using Eclipse for development of programs and having to make them open source.
But it sounds like you think that the Eclipse license forces products to be developed using it to be open-sourced. That's not true even for GPL-licensed editors, much less the license that Eclipse uses.
Arguing against open-sourcing government-developed software is questionable anyway. At one time the principle was that if the taxpayers paid for it, the taxpayers owned it, and they had a right to the source code. I know that the RIM DBMS developed by Being was open source for that reason - I was given the task of porting it to a minicomputer. I've heard rumors that the Oracle, Ingres and PostgreSQL DBMS's are all descendents of an open-source system developed for the US government, and likewise the PRIMOS operating system originally developed by Honeywell but used by the Honeywell defectors who founded Prime Computer.