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LanguageTool as a Java-based spell checker

Note: We recommend using the LanguageTool HTTP server instead of using the Java API directly.

Why use LanguageTool?

It’s easy to use LanguageTool as a spell checker in your Java projects. While you can also use existing projects like HunspellJNA or HunspellBridJ (at Maven Central), LanguageTool has some advantages:

  1. It provides spell checking, but adding more powerful checks, including several grammar checks, is very easy.
  2. Our goal is to provide 100% pure Java code, whereas the Hunspell-based alternatives linked above require native code. We’re not there yet for all languages - if in doubt, run mvn dependency:tree on your LanguageTool-based Maven project. If the dependencies contain hunspell-native-libs, LanguageTool also uses Hunspell internally for at least one of your languages and thus also requires native libraries.
  3. Hunspell can be slow when it comes to generating suggestions for misspelled words. For languages where LanguageTool does not internally use Hunspell (see item 2), it’s faster in generating suggestions.
  4. LanguageTool is available at Maven Central and comes with dictionaries included. For most languages, those dictionaries are the Hunspell dictionaries also used for LibreOffice/OpenOffice.

How?

See Java API for the Maven dependency you need to specify. Then, use code like this to find only spelling errors in a string:

    JLanguageTool langTool = new JLanguageTool(new BritishEnglish());
    for (Rule rule : langTool.getAllRules()) {
      if (!rule.isDictionaryBasedSpellingRule()) {
        langTool.disableRule(rule.getId());
      }
    }
    List<RuleMatch> matches = langTool.check("A speling error");
    for (RuleMatch match : matches) {
      System.out.println("Potential typo at characters " +
          match.getFromPos() + "-" + match.getToPos() + ": " +
          match.getMessage());
      System.out.println("Suggested correction(s): " +
          match.getSuggestedReplacements());
    }

If you want more than just spell checking, just remove the first for loop to activate all rules. See our development documentation for how those rules work. Need help? Just ask in our forum.

Extending the dictionary

See this page

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