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3.8 Code Improvements and Best Practices

Defaults

Replace code like 

    Properties defaults = new Properties();
    ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
    InputStream input = classLoader.getResourceAsStream("defaultconfig.properties");
    try {       
        defaults.load(input);
        }
    catch (IOException e) {
        e.printStackTrace();        
        }

with simply using mConfig.

Its module mConfigSourceJAR automatically loads defaults from .config/CONFIGNAME.EXTENSIONS in the resource folder of your JAR - besides all its other locations.

So, you can remove blocks like the above entirely.

Common Pitfalls and Feature Flags

Common mistakes when starting with mConfig, and the feature flags that help avoid them:

  • Redundant Null Checks: By default, EXCEPTION_ON_MISSING_ENTRY is true, so getters throw ConfigException instead of returning null. This removes the need for if (value == null) value = "placeholder" boilerplate.

Replace: 

String version = config.getString("version");
if (version == null) {
    version = "unknown";
}

With: 

try {
    String version = config.getString("version");
    // use version
} catch (ConfigException e) {
    // handle missing value once
}
Reminder: You can provide defaults in the resource folder of your JAR.

  • Manual null handling for missing values: Alternatively, use EXCEPTION_ON_MISSING_ENTRY=false and DEFAULT_ON_MISSING_ENTRY=true to automatically return scheme defaults instead of null.

  • Manual strictness checks: Set SCHEME_STRICT_MODE=true to reject unknown keys at runtime.

  • Manual scope fallback loops: Control with FALLBACKS_ACROSS_SCOPES (for reads) and WRITE_FALLBACK_ACROSS_SCOPES (for writes).

  • Custom format probing: Configure FILE_FORMAT_READING_PRIORITIES and FILE_FORMAT_WRITING_PRIORITIES declaratively instead of hardcoding.

These features promote a declarative style, reducing boilerplate and errors.