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Java Code Style

These are our basic style rules for new Java code in LanguageTool. For IntelliJ IDEA, you might want to use these inspection settings.

• Indent by 2 spaces.
• Use curly braces even if there’s only one statement in the if block.
• Do not use final for parameters or local variables, but write your code as if there was a final, i.e. do not re-assign local variables. Configure your IDE to help you with that.
  • For IntelliJ IDEA, the warnings (called “inspections”) to activate are “Reuse of local variable” and “Assignment to method parameter”.
• Use final for member variables if possible.
• Try to make classes immutable. That means that an object, once created, cannot be changed anymore. This helps making code more robust. Obviously, not everything in a complex object-oriented software can be immutable.
• Do not remove public methods, but mark them deprecated and keep them working. Use the @deprecated javadoc tag to document the method/class to be used instead.
• Add a @since x.y javadoc annotation to all new non-private methods, with x.y being the version number of the next release.
• Add @Nullable to methods that might return null, no matter if these methods are public or not.
• Do not share same package path among submodules/subprojects, ex. between language-en and language-core. It is known as split package problem that prevent a migration for Java Platform Module System (JPMS) introduced in Java 9. Each individual language module should have its own and unique package path which will end with a language code, ex. org.languagetool.language.en and org.languagetool.language.rules.en for English language project.

Examples for proper use of whitespace:

    if (var == 2) {
      statements;
    }
    
    if (var != 3) {
      statements;
    } else {
      statements;
    }
    
    if (var == 1 && foo == 5) {
      statements;
    } else if (condition) {
      statements;
    } else if (condition) {
      statements;
    }
    
    try {
      statement;
    } catch (Exception e) {
      statement;
    } finally {
      statement;
    }

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