multiple-language.md

The error messages have been translated to several languages by contributors, defined in the jsv-messages.properties resource bundle under https://github.com/networknt/json-schema-validator/tree/master/src/main/resources. To use one of the available translations the simplest approach is to set your default locale before running the validation:

// Set the default locale to German (needs only to be set once before using the validator)
Locale.setDefault(Locale.GERMAN);
JsonSchemaFactory factory = JsonSchemaFactory.getInstance(SpecVersion.VersionFlag.V201909);
JsonSchema schema = factory.getSchema(source);
...

Note that the above approach changes the locale for the entire JVM which is probably not what you want to do if you are using this in an application expected to support multiple languages (for example a localised web application). In this case you should use the SchemaValidatorsConfig class before loading your schema:

// Set the configuration with a specific locale (you can create this before each validation)
SchemaValidatorsConfig config = new SchemaValidatorsConfig();
config.setLocale(myLocale);
JsonSchemaFactory factory = JsonSchemaFactory.getInstance(SpecVersion.VersionFlag.V201909);
JsonSchema schema = factory.getSchema(source, config);
...

Besides setting the locale and using the default resource bundle, you may also specify your own to cover any languages you choose without adapting the library's source, or to override default messages. In doing so you however you should ensure that your resource bundle covers all the keys defined by the default bundle.

// Set the configuration with a custom resource bundle (you can create this before each validation)
ResourceBundle myBundle = ResourceBundle.getBundle("my-messages", myLocale);
SchemaValidatorsConfig config = new SchemaValidatorsConfig();
config.setResourceBundle(myBundle);
JsonSchemaFactory factory = JsonSchemaFactory.getInstance(SpecVersion.VersionFlag.V201909);
JsonSchema schema = factory.getSchema(source, config);
...