There are a lot of ways to handle an unknown value. I almost always use nulls to represent these internally, and use a default value at the end. So the library makes these cases easier for me.
This cannot be null. XML always stores things as strings, but often we really want a number. Notice that we are continuing the theme of converting an error into a default value. Remember all the types of errors we just discussed? This is one more for the list. The right value depends on context. What if a company has no debt? The default is to treat that as a null and display it as a blank. But there are alternatives. This function returns a null, instead. This routine allows you to iterate though the items one at a time.
For example when the client receives all the data in the top list, it wants to iterate through the data one row at a time. This handles errors in the normal way. If there is any sort of problem, this returns an empty list. As with all of these functions, there was already a way to do this.
This function just provides an easier way. This will never be null. Smart programmers are good at stealing a working solution from somewhere else. While some of the details have changed, the basic idea gets reused a lot.
Since it is easy to return a default value, sometimes we use that mechanism to report an error. We find some value that we can return as the default, and recognize later and an error.
For example, I often specify -1 as the default user id, since I know that all valid user ids are greater than 0.
How many shades of transparent do you need? This will be returned in case of any error. Mostly the server creates and writes while the client reads and interprets. But not always. The problems are the same for writing as for reading. The standard libraries give you all the pieces you need, but they are so hard to use. This library makes the common cases easier. Our software exists on a lot of clients and servers on a lot of different platforms.
We need to make sure they can all talk with one another. Java makes you create a factory which creates another factory which creates the actual document.
That seems like a long and convoluted process, even for Java! This next item is marked private. You can just ask this library to give you a blank document. This will be null if there are any errors. The standard Java libraries give you two types of options for reading an XML document. There are low level routines, where you create one type of stream only to convert it to another type of stream, etc. All of those long and complicated stream functions give you options that almost no one ever uses.
They are complicated and you always have to look them up to get your code right. And the high level routines are only good if you want exactly what they are offering. Sure, if I wanted to load a message from a normal web server or FTP server, that would be great. This function takes in a string, which is a very common way to store this type of data. The string could come from anywhere. A file. Then all you have to do to read the whole file is specify the location and it will parse and populate the annotated POJO's.
This will do all the type conversions and validation. You can also annotate for persister callbacks if required. Reading it can be done like so. Depending on your application and the scope of the cfg file, a properties file might be the easiest. Sure it isn't as elegant as xml but it certainly easier. Use java. It's easy to write the configuration files by hand , or use the corresponding XMLEncoder with some setup to write new objects at run-time.
This is what I use. This really makes things easier for me. It's especially nice when I'm reading a config file that was saved by and older version of the software, or was manually edited by a user. It's very robust and won't throw an exception if some data is not exactly in the format you expect.
It's incredibly simple and easy to use. Hope it's useful for you. How are we doing? Please help us improve Stack Overflow. Take our short survey. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 13 years ago. Active 4 years, 8 months ago. Viewed k times. Jonik Add a comment. Active Oldest Votes. You could always use the standard JDK method of getting a document : import java.
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