Which type of resource file to use to store constants

Question

I am developing an application that tests web Services, and I use JUnit parameterized tests. I want to read parameters from a resources file. I am wondering which is the best way to store these parameters.

1. In a .properties file ?

   test1.inputPath= C:\\Path
   test1.expectedOutputPath= C:\\Path
   test2.inputPath= C:\\Path2
   test2.expectedOutputPath= C:\\Path2
   

2. In an xml file?

   <test>
     <inputPath>  C:\Path <\inputPath>
     <expectedOutputPath>  C:\Path <\expectedOutputPath>
   <\test>
   <test>
     <inputPath>  C:\Path2 <\inputPath>
     <expectedOutputPath>  C:\Path2 <\expectedOutputPath>
   <\test>
   

3. Other way to do this?

Thanks.

Answer 1

The best solution that I found for my problem is to use PropertiesConfiguration of Apache Commons Configuration. It is very simple to use:

In my .properties file :

test1= Path1,Path2
test2= Path3,Path4

Then I read the .properties file automatically and I retrieve paths as a String array for each test.

@Parameters
public static Collection<Object[]> readPropertiesFile(){
    ArrayList<Object[]> result= new ArrayList<Object[]>();
    try {
        Configuration config = new PropertiesConfiguration("testPaths.properties");
        Iterator<String> keys=config.getKeys();
        while(keys.hasNext()){
            String[] paths= config.getStringArray(keys.next());
            result.add(paths);          
        }
    } catch (ConfigurationException e) {
        e.printStackTrace();
    }
    return result;
}

Answer 2

Do not try to make your life more complicated ;) You can easily read property files in this way:

Properties prop = new Properties();
InputStream input = new FileInputStream(fileName);
prop.load(input);
String s = prop.getProperty("test1.inputPath");

and import:

import java.util.Properties;

is it still complicated for you?

Answer 3

The answer is, of course, there are MANY ways of doing it.

First ask yourself: do these properties will change? Are they parameters or are they constants? For example, the number of the states, what are the chances they will change? In this case you need a constant, not a parameter.

Now, if you are looking for something that can changed at runtime then you should look into properties and resource bundles.

---

If all you need are constants, then you can do something like:

public interface Constants
{
    public char NUMBER_ONE = '1';
    public long A_LONG_TIME_AGO = 1321322;
    public String CANT_BREAK_WITH_IRON_PICKAXE= "OBSIDIAN";
}

There are many advantages in using interfaces: they don't need to be instantiated, won't slow down your system with IO access, and all attributes are static final.

---

However, if you need to load the values during runtime, then use properties files. Although all answers here are good, the only one I consider good enough is Spring's @Configuration and @ImportResource, which are injected, allow for nice mocking, and integrate nicely with the rest of the Spring framework, and can be easily overridden with -D from the command line.

Example on how to load properties files using a mix of xml and properties files: Spring-Boot: How do I reference application.properties in an @ImportResource