Translate a Java (Spring) app into Spanish

What Spanish changes in a Spring UI

Spanish uses the Latin alphabet and runs left to right, so nothing breaks structurally. The problems show up on screen.

• Inverted punctuation. Questions open with ¿ and exclamations with ¡, so the whole sentence must live in one value: confirm.delete=¿Desea eliminar {0}?. If a Thymeleaf template appends the question mark itself, the opening sign will be missing or doubled.
• Length. Spanish runs longer than English and close to French. From an English source, “Sign in” becomes Iniciar sesión and “Delete account” Eliminar cuenta: check navigation bars, buttons and narrow table headers.
• Grammatical gender. A shared message such as {0} deleted needs eliminado or eliminada depending on the noun. Separate keys (file.deleted, invoice.deleted) avoid awkward fixes.
• Form of address. Decide between tú and usted up front, and for Spain between vosotros and ustedes: ¿Tenéis cuenta? sounds foreign in Mexico.
• Regional vocabulary. ordenador in Spain, computadora in Latin America; likewise móvil and celular.

Plurals, dates, numbers and locale resolution

Some of the localisation work sits in your Java code rather than in the translation.

• Plurals. Spanish has three CLDR categories: one, many and other. Zero falls under other (0 archivos), and many covers large round numbers that take “de”: 1 millón de usuarios. MessageFormat’s choice does not know these categories; {0,choice,0#ningún archivo|1#un archivo|1<{0} archivos} covers most screens, but review each branch.
• Dates and numbers. Keep them out of the message text and format them with DateTimeFormatter or NumberFormat and the request Locale. Spain writes 1.234,56, Mexico 1,234.56. Date formats found in a file are not translated by Manuce.
• File naming. messages_es.properties serves all Spanish locales; messages_es_ES.properties or messages_es_MX.properties add country variants that fall back to messages_es.
• Spring fallback. In Spring Boot, spring.messages.fallback-to-system-locale defaults to true, so a key missing from the Spanish file may appear in the server’s language rather than from messages.properties. Worth checking if an English or French string turns up on a Spanish page.

What Manuce returns, and what it does not do

You get the same file in the same format: indentation, key order, comments, line endings, encoding and BOM preserved. Only the values change.

• Unicode escapes. If your source writes accented characters as \u00E9, the Spanish file keeps that convention: ñ comes out as \u00F1 and ¿ as \u00BF. A plain UTF-8 file stays plain UTF-8.
• Continuation lines. Values split with a trailing \ are handled as a single string.
• MessageFormat apostrophes. In a message with arguments, a single quote must be doubled. English contractions such as “don’t” usually vanish in Spanish (no), but any apostrophe the translation introduces is handled.
• Validation. Each translated value is checked against the source for placeholders ({0}, {min}) and tags such as <b>. If a mismatch persists, the source value is kept and the report says so.
• Left as is. Keys, empty values, URLs, email addresses, numbers, colours, date formats, identifiers and anything marked as non-translatable.

Manuce does not touch your Java code or templates, and does not produce an es_MX variant alongside an es_ES one by itself: for two markets, duplicate the file and adjust the vocabulary. It does not provide certified (sworn) translation either.

Preparing the file and checking the result

Before uploading:

• Start from your most complete base file, usually messages.properties under src/main/resources. If you use Bean Validation, send ValidationMessages.properties too; its {min} and {max} are checked like any other placeholder.
• Add comments above ambiguous keys, for example # button, max 12 chars or # feminine noun: factura. Comments are kept in the output.
• Note the form of address (tú or usted) and the target market.

After delivery:

1. Read the report: a value left in the source language often points to a placeholder problem in the original.
2. Save the file under the right locale name and run the app with Accept-Language: es or es-ES.
3. Look at screens containing ¿, ñ and accents; garbled characters mean the declared encoding (spring.messages.encoding) does not match the file.
4. Test plurals with 0, 1 and a large number.

Spanish is charged at the base rate (×1), counting only the words in the values.

In practice

1. Take messages.properties (and ValidationMessages.properties if used) from src/main/resources.
2. Comment ambiguous keys and note the form of address and target country.
3. Upload the file, pick a level and read the free sample.
4. Save the returned file as messages_es.properties (or es_ES, es_MX) next to the original.
5. Read the report, then test the app with Accept-Language: es.