Feeding data as opposed to hardcoding

Question

Most of the examples I see in the forum consists of hardcoding the files or strings. for example,
FileOutputStream fos = new FileOutputStream
("config.txt");
or,
String name="abcdegh";
But, for real world applications, you can't hardcode a file or data in the code.
Can you guys give me examples of what kind of things done dynamically as opposed to hardcoding?

Answer 1

Although there is nothing forcing you to use a particular format, if you don't use one that's already implemented you'll have to do it yourself.
There are many ways to load configuration data into an application. Three ways come to mind most readily:
1) Properties files -- a simple text file listing mappings between a unique string key or "property name", and a string value. See the doc for java.util.Properties, especially the load() method, for more info: http://java.sun.com/j2se/1.3/docs/api/java/util/Properties.html#load(java.io.InputStream) .
2) Object serialization -- if having a human-readable file isn't important but load time is, you may want to create your own config properties class that implements the Serializable interface. Use ObjectInput(or Output)Stream to read/write properties directly into an object.
3) XML files -- I've seen some apps that require config data that is human-readable and organized in a hierarchy, use XML files to load in property data and settings. With the inclusion of XML processing in the standard platform as of JDK 1.4 along, this becomes a more viable option.
Another means you may want to explore is something new to JDK 1.4: java.util.prefs package -- http://java.sun.com/j2se/1.4/docs/api/java/util/prefs/package-summary.html
Food for thought.