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I have an application written in Java. In is stored in several files. It uses different classes with different methods. The code is big and complicated. I think it would be easier to understand the code if I have a graphical model of the code (some kind of directed graph). Are there some standard methods for visualization of code. I am thinking about usage of UML (not sure it is a correct choice). Can anybody recommend me something?
ADDED:
I consider two possibilities:
Creating the graph by hands (explicitly).
Creating graph in an automatic way. For example to use some tools that read the available code and generate some graph describing the structure of the code.
ADDED 2:
It would be nice to have something for free.
I tried using a number of UML tools and found that the reverse-engineering capabilities in most UML tools were not helpful for understanding code. They focus on designing needs and reverse-engineering capabilities often just ends up showing huge pictures of lots of useless information. When I was working on the Microsoft Office codebase, I found using a pen-and-paper more helpful that the typical design/modelling tools.
You typically want to think about doing this in a number of ways:
Use your brain: Someone else mentioned it - there is no substitute to actually trying to understand a code base. You might need to take notes down and refer back to it later. Can tools help? Definitely. But don't expect them to do most of the work for you.
Find documentation and talk to co-workers: There is no better way than having some source describe the main concepts in a codebase. If you can find someone to help you, take a pen and paper, go to him and take lots of notes. How much to bug the other person? In the beginning - as much as is practical for your work, but no amount is too little.
Think about tools: If you are new to a part of a project - you are going to be spending a significant amount of time understanding the code, so see how much help you can get automatically. There are good tools and bad tools. Try to figure out which tools have capabilities that might be helpful for you first. As I mentioned above, the average UML tool focuses more on modeling and does not seem to not be the right fit for you.
Time vs Cost: Sure, free is great. But if a free tool is not being used by many people - it might be that the tool does not work. There are many tools that were create just as an exploration of what could be done, but are not really helpful and therefore just made available for free in hopes that someone else will adopt it. Another way to think about it, decide how much your time is worth - it might make sense to spend a day or two to get a tool to work for you.
Once there, keep these in mind when going trying to understand the project:
The Mile High View: A layered architectural diagram can be really helpful to know how the main concepts in a project are related to one another. Tools like Lattix and Architexa can be really helpful here.
The Core: Try to figure out how the code works with regards to the main concepts. Class diagrams are exceptionally useful here. Pen-and-paper works often enough here, but tools can not only speed up the process but also help you save and share such diagrams. I think AgileJ and Architexa are your best bets here, but your average UML tool can often be good enough.
Key Use Cases: I would suggest tracing atleast one key use case for your app. You likely can get the most important use cases from anyone on your team, and stepping through it will be really helpful. Most IDE's are really helpful here. If you try drawing them, then sequence diagrams arethe most appropriate. For tools here I think MaintainJ, JDeveloper and Architexa are your best bets here.
Note: I am the founder of Architexa - we build tools to help you understand and document Java code, but I have tried to be unbiased above. My intention is to suggest tools and options given that this is what I focused on as part of my PhD.
The most important tool you should use is your brain, and it's free.
There's no reason why you have to use any sort of standard method of visualization, and you can use whatever media you like. Paper, whiteboard, photoshop, visio, powerpoint, notepad: all of these can be effective. Draw a diagram of classes, objects, methods, properties, variables - whatever you think is useful to see in order to understand the application. The audience is not only other members of your team, but also yourself. Create diagrams that are useful for you to look at and quickly understand. Post them around your workspace and look at them regularly to remind yourself of the overall system architecture as you build it.
UML and other code documentation standards are good guidelines for the types of diagrams you can do and the information you should consider including. However, it is overkill for most applications and basically exists for people who can't take personal responsibility for documenting without standards. If you follow UML to the letter, you'll end up spending way too much time on your documentation instead of creating your application.
It is stored in several files. It uses different classes with different methods. The code is big and complicated.
All Java code written outside the school is like that, particularly for a new developer starting on a project.
This is an old question, but as this is coming up in Google searches, I am adding my response here so that it could be useful to the future visitors. Let me also disclose that I am the author of MaintainJ.
Don't try to understand the whole application
Let me ask you this - why do you want to understand the code? Most probably you are fixing a bug or enhancing a feature of the application. The first thing you should not try to do is to understand the whole application. Trying to understand the entire architecture while starting afresh on a project will just overwhelm you.
Believe me when I say this - developers with 10+ years of solid coding experience may not understand how certain parts of the application work even after working on the same project for more than a year (assuming they are not the original developers). They may not understand how the authentication works or how the transaction management works in the application. I am talking about typical enterprise applications with 1000 to 2000 classes and using different frameworks.
Two important skills required to maintain large applications
Then how do they survive and are paid big bucks? Experienced developers usually understand what they are doing; meaning, if they are to fix a bug, they will find the location of the bug, then fix it and make sure that it does not break the rest of the app. If they need to enhance a feature or add a new feature, most of the time, they just have to imitate an existing feature that does a similar thing.
There are two important skills that help them to do this.
They are able to analyze the impact of the change(s) they do while fixing a bug. First they locate the problem, change the code and test it to make sure that it works. Then, because they know the Java language well and the frameworks 'well enough', they can tell if it will break any other parts of the app. If not, they are done.
I said that they simply need to imitate to enhance the application. To imitate effectively, one needs to know Java well and understand the frameworks 'well enough'. For example, when they are adding a new Struts Action class and adding to the configuration xml, they will first find a similar feature, try to follow the flow of that feature and understand how it works. They may have to tweak a bit of the configuration (like the 'form' data being in 'request' than in 'session' scope). But if they know the frameworks 'well enough', they can easily do this.
The bottom line is, you don't need to understand what all the 2000 classes are doing to fix a bug or enhance the app. Just understand what's needed.
Focus on delivering immediate value
So am I discouraging you from understanding the architecture? No, not at all. All I am asking you is to deliver. Once you start on a project and once you have set up the development environment on your PC, you should not take more than a week to deliver something, however small it may be. If you are an experienced programmer and don't deliver anything after 2 weeks, how can a manager know if you really working or reading sports news?
So, to make life easier for everyone, deliver something. Don't go with the attitude that you need to understand the whole application to deliver something valuable. It's completely false. Adding a small and localized Javascript validation may be very valuable to the business and when you deliver it, the manager feels relieved that he has got some value for his money. Moreover, it gives you the time to read the sports news.
As time passes by and after you deliver 5 small fixes, you would start to slowly understand the architecture. Do not underestimate the time needed to understand each aspect of the app. Give 3-4 days to understand the authentication. May be 2-3 days to understand the transaction management. It really depends on the application and your prior experience on similar applications, but I am just giving the ballpark estimates. Steal the time in between fixing the defects. Do not ask for that time.
When you understand something, write notes or draw the class/sequence/data model diagram.
Diagrams
Haaa...it took me so long to mention diagrams :). I started with the disclosure that I am the author of MaintainJ, the tool that generates runtime sequence diagrams. Let me tell you how it can help you.
The big part of maintenance is to locate the source of a problem or to understand how a feature works.
MaintainJ generated sequence diagrams show the call flow and data flow for a single use case. So, in a simple sequence diagram, you can see which methods are called for a use case. So, if you are fixing a bug, the bug is most probably in one of those methods. Just fix it, ensure that it does not break anything else and get out.
If you need to enhance a feature, understand the call flow of that feature using the sequence diagram and then enhance it. The enhancement may be like adding an extra field or adding a new validation, etc. Usually, adding new code is less risky.
If you need to add a new feature, find some other feature similar to what you need to develop, understand the call flow of that feature using MaintainJ and then imitate it.
Sounds simple? It is actually simple, but there will be cases where you will be doing larger enhancements like building an entirely new feature or something that affects the fundamental design of the application. By the time you are attempting something like that, you should be familiar with the application and understand the architecture of the app reasonably well.
Two caveats to my argument above
I mentioned that adding code is less risky than changing existing code. Because you want to avoid changing, you may be tempted to simply copy an existing method and add to it rather than changing the existing code. Resist this temptation. All applications have certain structure or 'uniformity'. Do not ruin it by bad practices like code duplication. You should know when you are deviating from the 'uniformity'. Ask a senior developer on the project to review the changes. If you must do something that does not follow the conventions, at least make sure that it's local to a small class (a private method in a 200 line class would not ruin the application's esthetics).
If you follow the approach outlined above, though you can survive for years in the industry, you run the risk of not understanding the application architectures, which is not good in the long run. This can be avoided by working on bigger changes or by just less Facebook time. Spend time to understand the architecture when you are a little free and document it for other developers.
Conclusion
Focus on immediate value and use the tools that deliver that, but don't be lazy. Tools and diagrams help, but you can do without them too. You can follow my advice by just taking some time of a senior developer on the project.
Some plugins I know for Eclipse:
Architexa
http://www.architexa.com/
nWire
http://www.nwiresoftware.com/
If you want to reverse engineer the code, you should try Enterprise Architect
have you tried Google CodePro Analytix ?
it can for example display dependencies and is free (screenshot from cod.google.com):
Here is a non UML Tool which has very nice visualization features.
You can mapping the lines of code per class / method to colors / side lenght of rectangles.
You can also show the dependencies between the classes.
http://www.moosetechnology.org/
The nice thing is, you can use Smalltalk scripting for displaying what you need:
http://www.moosetechnology.org/docs/faq/JavaModelManipulation
Here you can see how such a visualization looks like:
http://www.moosetechnology.org/tools/moosejee/casestudy
JUDE Community UML used to be able to import Java, but it is no longer the case. It is a good, free tool.
If your app is really complex I think that diagrams won't carry you very far. When diagrams become very complex they become hard to read and lose their power. Some well chosen diagrams, even if generated by hand, might be enough.
You don't need every method, parameter, and return value spelled out. Usually it's just the relationships and interactions between objects or packages that you need.
Here is a another tool that could do the trick:
http://xplrarc.massey.ac.nz/
You can use JArchitect tool, a pretty complete tool to visualize your code structure using the dependency graph, and browse you source code like a database using CQlinq.
JArchitect is free for open source contributors
Some great tools I use -
StarUML (allows code to diagram conversion)
MS Visio
XMind (very very useful for overview of the system)
Pen and Paper!
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Getting a clue at / debug a huge Java Swing App I’ve inherited
I joined a new project and have to understand the project's product. I am more familiar with daemon/standalone type applications but this time i have to get involved in Java GUI applications using Swing.
I have to familiarise myself with quite a large code base. I have been trying to do this for the last 3 days and find that i am struggling to get the "Big picture". The event driven model means that things can happen and are triggered from anywhere within the application.
At the moment i am still struggling to work out how the screen is built and put together. I can see the code but just struggling to follow because it is not the usual model that i am used to where you can just follow the references, calls etc.
Is there anything i can do to simplify/speed this learning process? I tend to understand things better when i see them in a diagrammatic form (class diagrams, sequence diagrams etc.). I am trying to see if i can try and find a tool that can reverse engineer the code to UML so that i can get a better understanding but because the code base is huge, the UML diagrams that will be generated will probably be unusable because of the number of classes involved.
Any advice would be appreciated.
Guess you are dealing with a legacy application and all the bagage that comes along with it.
So even if you got to generate a UML, I am willing to bet that it will not help you, since you will (most likely) find it to be a giant mess. Things that used to resemble a Design Pattern got messed up, code snippets copied and pasted from a to b to c, etc...
Your best bet (from my experience) is to follow the Programm logic in the debugger when you execute certain actions. At least thats what I found to be most useful when faced with similar senarios.
Get good IDE. I would recommend itellij idea for this task. It's not free, but it beats eclipse on every occasion
I agree with dngfng, a legacy application will come with its 'baggage'. Only 'time' and lot of discussion with existing developers will sort that.
Along with the other suggestions here, I d say just 'use' the product from the user point of view. Perform all the actions that are promised in the features till you get a hang of using the software. After that when you look at the codebase, it may get a little more intuitive.
We have an agile enterprise application built on JSP and Servlet without any design strategy.
This application was built in early 2002 considering 1000 users. After 2002, we received lots of requests from the marketing partners.
Currently, the application has lots of spaghetti code with lots of Ifs and elses. One class has more than 20,000 lines of code with a huge body of functions without abstraction.
Now, we need to support billions of records,
what we need to do immediately and gradually?
We have to refactor the application?
Which framework, we need to use?
How the usage of the framework will be helpful to the end users?
How to convince the leaders to do the refactoring?
How to gain the faster response time as compare to the current system?
Here is how I would approach this if I had appropriate company resources at my disposal (yeah right):
Get a good QA process going, with automated regression testing set up before making significant changes. I don't care how good you are, you can't put a system like that under unit test and reasonably control for regressions.
Map out interdependencies, see how much an individual class can be tested as a unit.
How do you eat an elephant? One bite at a time. Take a given piece of required functionality (preferably something around the increase load requirements) and refactor the parts of the class or classes that can be worked on in isolation.
Learn how do 3 above by reading Working Effectively with Legacy Code.
Convenient way to refactor the application.
There are no "convenient" or "easy" ways to refactor an existing codebase, especially if the codebase looks like spaghetti.
... what we need to do immediately and gradually?
That's impossible to answer without understanding your system's current architecture.
We have to refactor the application?
On the one hand, the fact that you have a lot of poorly designed / maintained code would suggest that it needs some refactoring work.
However, it is not clear that it will be sufficient. It could be that a complete rewrite would be a better idea ... especially if you need to scale up by many orders of magnitude.
Which framework, we need to use?
Impossible to answer without details for your application.
How the usage of the framework will be helpful to the end users?
It might reduce response times. It might improve reliability. It might allow more online users simultaneously. It might do none of the above.
Using a framework won't magically fix a problem of bad design.
How to convince the leaders to do the refactoring?
You need to convince them that the project is going to give a good return on investment (ROV). You / they also need to consider the alternatives:
what happens if you / they do nothing, or
is a complete rewrite likely to give a better outcome.
How to gain the faster response time as compare to the current system?
Impossible to answer without understanding why the current system is slow.
The bottom line is that you probably need someone from outside your immediate group (e.g. an external consultant) to do a detailed review your current system and report on your options for fixing it. It sounds like your management don't trust your recommendations.
These are big, big questions. Too broad for one answer really.
My best advice is this: start small, if you can. Refactor piece by piece. And most importantly, before touching the code, write automated tests against the current codebase, so you can be relatively sure you haven't broken anything when you do refactor it.
It may not be possible to write these tests, as the code may not be testable in it's current format. But you should still make this one of your main goals.
By definition refactoring shouldn't show any difference to the users. It's only to help developers work on the code. It sounds like you want to do a more extensive rewrite to modernize the application. Moving to something like JSF will make life a lot easier for developers and will give you access to web component libraries to improve the user experience.
It is a question which needs a lengthy answer. To start with I would suggest that the application is tested well and is working as per the specification. This means there are enough unit, integration and functional tests. The functional tests also have to be automated. Once these are in place, a step by step refactoring can take place. Do you have enough tests to start?
yesterday i went to English Class and met new friend, he said with me about the worked he did (still now i have studied in school).
In his company, the customers have
many request for their project, if you
use framework but not understand all
component or like that, you would meet
problem with your source code and you
didn't fix it because it built by
another one. And Cusomters paid money
for you to developed their project,
you must completed it by yourself, and
if occur error you would to fix it.
But if you use framework you can fix
or not it's 50/50 percent for you.
I wonder about his said. Can you help me the best way me must choice? Framework or not?
We have many kinds customers and we must work with some technologies such as struts/ hibernate/Spring/ or so on...if not use framework the time we complete project so long but if use it i don't believe all component of it i can understand.
Thank you for your suggest!
• Should I use existing frameworks in my projects?
Yes, in general you should. The creators of the frameworks have put large amounts of work into them to make them good, and many other people use the frameworks, too. That means that the code is well-tested in practice. When you write your own code, it will be tested by just you and your team.
• What happens if there are bugs in the framework, how could I possibly fix them?
Good question, I don't know an answer right now. Most probably you would write some own code to work around the problem, like a small wrapper class.
• Do I have to understand the complete frameworks before I can use them?
No, you don't. Some frameworks are large and cover each and every aspect of software development. In most cases you only have to learn the things you really want to do, and some more. But not every detail.
• When I use a framework, is that cheating, since my customer wants me to develop software?
No, it isn't. Your customer doesn't really want you to do much work, he rather wants his projects to be done and finished. That means if you can do less work and profit from other's work, that's usually fine.
• We must work with third-party products like Structs/Hibernate/Spring, and if we are forced to implement them ourselves, the projects will take very long.
You really don't want to implement everything that Spring, Hibernate and Struts have already solved. So use these frameworks and be glad that someone else did the work. It's many man years that you will save.
There are many factors to consider:
Is the framework commercial? If so, does the framework have a responsive support team with the ability to provide demos, documentation, consulting, "work-abouts" and hot-fixes? Can you purchase the source code to make any tweaks you need? (Is it worth it to may extra to have access to the source and can you redistribute a modified copy?)
Is the framework "open source"? If so, does the framework have a responsive forum or mailing list that can provide answers to problems? Are there paid consultants or contractors? Is the documentation good? Is the framework popular and is it being maintained? Can you apply hot-fixes as needed?
How much "time" is required to learn the framework? Do special conventions need to be used? Does using the framework cause some lock-in that will be incompatible with future requirements?
Etc, etc.
This all leads to: Does using the framework ultimately make work more productive?
I think it depends on the size of the project. If you're working in a small project probably it's a nonsense to use a framework, because you're going to be less productive.
Instead if you're working in a big project the framework can help you a lot.
For example, in the case of Hibernate, if you're working in a project with three or four objects/tables, maybe it's a nonsense use it, because probably it's much easier to work with JDBC, and even the software will run much faster. But if you're in a project with docens of objects/tables working with JDBC can be a big headache, and hibernate helps you a lot.
The time you loose in the configuration of the framework is small compared to the big benefit in the simplification of the development.
According to the possible bugs in the framework, is important to use a framework with a good support and a good community which can help you to solve your problems.
Also if you use an open source framework you can try to solve the bug, add a new feature or modify an existing one to match with your project needs.
This seems to be a popular complaint on many programmer forums so I wouldn't be surprised if this question was already on here. Sorry if it has already been answered but I've searched and couldn't find one that relates to Java/OO.
I have a somewhat complicated application that was written a number of months ago. It works well, but is slow and the code is extremely ugly. Classes are split up for no logical reason, half the UI is in the logic code and it's really frustratingly built. I want to redesign and redevelop this program to the correct design standards, yet I don't want to break it completely. There's no design documents, no documentation, nothing but the code (with no formatting) and the built application.
What's the best way of taking an existing Java project, written in the most annoying way possible and redeveloping it in the best way possible? Are there any good tools that'll help me find speed bottlenecks or for extensive testing in NetBeans? Any help for a total novice of testing would be greatly appreciated.
EDIT: You're correct when saying that we don't really understand this program. It does what we want, but it also does other things and we're not exactly aware of, like creating strange graphics and weird numbers appearing on the UI. The main reason we want this redesigned is so that we can actually find out what's going on, but as I've said the code is so messy you'd think it was written by a genius that didn't want us to find out his secrets.
"with no formatting"
Netbeans has an automatic formatter option in the "Source" menu. That would be a good start.
"There's no design documents, no documentation, nothing but the code"
As you work out what parts do, it will serve you well (and your successors) to document this. That way you will start having documentation you can refer to.
Using JUnit to start adding some Unit Tests to sections before you refactor them wouldn't hurt either.
"I want to redesign and redevelop this program to the correct design standards, yet I don't want to break it completely."
Start small. Work out some simple things that could be designed better and concentrate on them first. Using the Refactor ability in Netbeans will help greatly with this. Concentrate on making sure everything that you refactor still works the same (which is why starting out small helps). The more of the small stuff that you clean up, the easier the bigger stuff will be when you come to it.
Also, make sure what you are refactoring is actually an improvement...
I would echo C. Ross's comments and add these strategies for common "bad code" scenarios I've dealt with in the past:
Code Duplication: The only thing worse than bad code is multiple copies of the same bad code. Get familiar with the entire code base by speed reading it (get it's flavour) and identify instances of cutting-and-pasting code. Refactor those to a single implementation and remove the duplication. That may be it - or you can continue to refine the single copy of that code.
Don't be in a hurry to fix it: Only clean up code that you actively need to maintain and/or understand. This is a variation of if it ain't broke don't fix it I like to call if you don't need to change it don't fix it. But, anytime you need to touch a piece of code take 10 extra minutes to clean it up. Maybe that's just adding formatting it, adding some inline comments, renaming variables to make sense, etc. Any code you need to update will most likely be revisted again in the future, and now you've made it all clean. Code you haven't had to actually change yet can remain ugly without harming anything.
Good luck :)
As already mentioned, an ugly code can be cleaned up by a monkey with a proper IDE so I wouldn't go to your manager with that argument alone.
Being pragmatic, I would go with:
grab some tools (a profiler, code duplication tools) to find a couple of pain points
for each point, come up with a battle plan how to solve it (with short specification, design, maybe code sample, test cases...).
go to your manager and let him decide which one to tackle first
The danger is to do too much and to try to clean everything. Depending on the size of the application, it may take years to clean it up (because you won't do this full time) so just be patient.
And of course, when you revisit part of the code, just clean it up with your favorite IDE.
Really the only answer is sweat equity, but some things that can help:
A good IDE with refactoring tools, such as Eclipse
Profiling tools for optimization
Code coverage tools, such as EclEmma
Javadoc, sometimes it helps to get a high level view of even bad code
Happy refactoring!
What you have is essentially a prototype. Tell your manager that that is what it is, and that it should be rewritten to reach production quality.
JProfiler is excellent, I was using it just yesterday in fact to find a performance bottleneck in some Java code I had.
If you can get some automated tests in place you'll be in a better position to start refactorring as you can then assetr that it's still functioning as expected. Specifically you should focus I think on very high level tests of the system, if it's a web app take a look at selenium and/or other web app testing frameworks.
Apart from that, be ready to head down a lot of dead ends, try and avoid taking too much change on at once if possible. The more you can break down the largre app into smaller chunks which you can take on one at a time the more succesful you're likely to be. Also, be prepared to accept that some of it may well remain crappy forever, if it ain't broke as they say, don't fix it.
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I find the nature of this question to be quite suited for the practical-minded people on Stack Overflow.
I'm setting out on making a rather large-scale project in Java. I'm not going to go into specifics, but it is going to involve data management, parsing of heterogeneous formats, and need to have an appealing interface with editor semantics. I'm a undergraduate student and think it would evolve into a good project to show my skill for employment -- heck, ideally it would even be the grounds for a startup.
I write to ask you what shortcuts I might not be thinking about that will help with a complicated project in Java. Of course, I am planning to go at it in Eclipse, and will probably use SWT for the GUI. However, I know that Java has the unfortunately quality of overcomplicating everything, and I don't want to get stuck.
Before you tell me that I want to do it in Python, or the like, I just want to reiterate why I would choose Java:
Lots more experience with algorithms in Java, and there will be quite a bit of those.
Want a huge library of APIs to expand functionality. ANTLR, databases, libraries for dealing with certain formats
Want to run it anywhere with decent performance
I am open-minded to all technologies (most familiar with Java, perl, sql, a little functional).
EDIT: For the moment, I am giving it to djna (although the low votes). I think all of your answers are definitely helpful in some respect.
I think djna hit better the stuff I need to watch out for as novice programmer, recognizing that I'm not taking shortcuts but rather trying not to mess up. As for the suggestions of large frameworks, esp. J2EE, that is way too much in this situation. I am trying to offer the simplest solution and one in which my API can be extended by someone who is not a J2EE/JDBC expert.
Thanks for bringing up Apache Commons, although I was already aware. Still confused over SWT vs. Swing, but every Swing program I've used has been butt ugly. As I alluded to in the post, I am going to want to focus most on the file interchange and limited DB features that I have to implement myself (but will be cautious -- I am aware of the concurrency and ACID problems).
Still a community wiki to improve.
Learn/use Spring, and create your project so it will run without a Spring config (those things tend to run out of control), while retaining the possibility to configure the parameters of your environment in a later stage. You also get a uniform way to integrate other frameworks like Hibernate, Quartz, ...
And, in my experience, stay away from the GUI builders. It may seem like a good deal, but I like to retain control of my code all the time.
Google-collections:
http://code.google.com/p/google-collections/
Joda Time for all date and time manipulations.
One of Hibernate or iBATIS to manipulate data in a database
Don't forget the IDE: Eclipse, Netbeans or IDEA if you have some cash and like it
Apache Commons has a lot of time saving code that will you most likely need and can reuse.
http://commons.apache.org/
A sensible build and configuration platform will help you along the way, Ant:
http://ant.apache.org/
or Maven (preferably):
http://maven.apache.org/
Especially as the size of the project, and the number of modules in the project increase.
There's getting the "project" completed efficiently and there are "short cuts". I suspect the following may fall into the "avoiding wasted effort" category rather be truly short cuts but if any of them get you to then end more quickly then I perhaps they help.
1). Decomposition and separation of concerns. You've already identified high-level chunks (UI, persistence layer, parser etc.). Define the interfaces for the provider classes as soon as possible and have all dependent classes work against those interfaces. Pay a lot of attention to the usability of those interfaces, make them easy to understand - names matter. Even something as simple as the difference between setShutdownFlag(true) and requestShutdown(), the second has explicit meaning and hence I prefer it.
Benefits: Easier maintenance. Even during initial development "maintenance" happens. You will want to change code you've already written. Make it easy to get that right by strong encapsulation.
2). Expect iterative development, to be refining and redesigning. Don't expect to "finish" any one component in isolation before you use it. In other words don't take a purely bottom up approach to developing your componenets. As you use them you find out more information, as you implement them you find out more about what's possible.
So enable development of higher level components especially the UI by mocking and stubbing low level components. Something such as JMock is a short-cut.
3). Test early, test often. Use JUnit (or equivalent). You've got mocks for your low level components so you can test them.
Subjectively, I feel that I write better code when I've got a "test hat" on.
4). Define your error handling strategy up front. Produce good diagnostics when errors are detected.
Benefits: Much easier to get the bugs out.
5). Following on from error handling - use diagostic debugging statements. Sprinkle them liberally throughout your code. Don't use System.out.println(), instead use the debugging facilities of your logging library - use java.util.logging. Interactive debuggers are useful but not the only way of analysing problems.
Don't discount Swing for the GUI. There are a lot of good 3rd party Swing libraries available (open source and commercial) depending on your needs e.g.
JGoodies Form Layout
SwingX
JFreeChart
Use logging framework (i.e. Log4J) and plan for it. Reliable logging system saves a lot of time during bug fixing.
For me big time-savers are:
use version-control (Subversion/Git)
use automatic builds (Ant/Make/Maven)
use Continuous-integration (Hudson/CruiseControl)
the apache-commons-libraries are very useful
Test Driven Development
Figure out the functionality you want and write tests to demonstrate the functionality. Then write just enough code to pass the tests. This will have some great side effects:
By writing just enough code to satisfy your requirements you will not be tempted to overbuild, which should reduce complexity and make your code cleaner.
Having tests will allow you to "refactor with confidence" and make changes to the code knowing you're not breaking another part of the system.
You're building quality in. Not only will you have assurance that you code "works, but if you really want to use this code as a sort of "resume" for potential employers, this will show them that you place a lot of value on code quality. This alone will set you apart from the majority of the developers out there.
Aside from that, I would agree that other big time savers are Spring, having an automated build (Maven), and using some form of source control.
For data persistency, if you're not certain that you must use SQL, you should take a look at alternate data-storage libraries:
Prevayler: an in memory database systems, using developing ideas like "crash only components", that make it easy to use and very performatic. May be used even for simple applications where you just need to save some state. It has a BSD License.
BerkleyDB Java Edition: a storage system with different layers of abstraction, so one can use it as a basic key-value storage (almost an in-disk hashtable) to a fully transactional ACID system. Take a look at it's licensing information because even some commercial software may use it for free.
Be aware that they have trade-offs when compared with each other or with a standard SQL database! And, of course, there may be other similar options around, but these are the ones I know and like. :)
PS: I was not allowed to post the respective links because I'm a new user. Just google for them; first hits are the right ones.
You can save time between restarts by using JavaRebel (commercial). Briefly, this tool allows you to write your code in Eclipse and have the code changes picked up instantly.
Spring Roo can not only get your project quickly kickstarted (using a sound architecture) but also reduce your ongoing maintenance. If you're thinking of using Spring, servlets, and/or JPA, you should definitely consider it. It's also easy to layer on things like security.