Code Style

A consistent code style helps to improve the approachability of code and reduce noise during pull requests caused by conflicting IDE settings between developers.

Tools

The project a few tools to detect and address style violations. These tools are run against all Pull Requests.

Spotless

Spotless is a tool that both detects and corrects style issues. This includes:

• Indentation using spaces, not tabs
• The order imports appear in
• Removal of unused imports
• Overall formatting of code
• Some safe code changes such as removal of unnecessary boxing.

To check for issues run the spotlessCheck gradle task - this will produce a report of all violations. Then to fix issues run spotlessApply.

If there are portions of code for which spotless checks should not be applied - perhaps a section of code that should be formatted in a particular way for readability - then it can be surrounded by a pair of comments containing spotless:off and spotless:on:

// spotless:off
public static final List<Vector2i> POSITIONS = List.of(
        new Vector2i(0, 1),
        new Vector2i(2, 3),
        new Vector2i(5, 8),
        new Vector2i(9, 13)
);
// spotless:on

Checkstyle

Checkstyle is a tool that can only detect and report style issues. It can be run using the checkstyleMain gradle task. It has been configured to report:

• Wildcard or star imports
• Names that don't match the standard java style. e.g. packages should have all lowercase names, non-constant variables should start with a lowercase letter, method names should start with a lowercase letter
• If statements that don't use braces
• Declaration order - this checks that elements in a type are declared in the following order:
  1. Static variables (public, then protected, then package, then private)
  2. Instance variables (public, then protected, then package, then private)
  3. Constructors
  4. Methods
• Case statements with code that falls through to another case statement. e.g.

switch (letter) {
    // This is fine, the case for 'a' has no code
    case 'a':
    case 'b':
        System.out.println("a or b");
        break;
    // This provokes a checkstyle error
    case 'c':
        System.out.println("only c");
    case 'd':
        System.out.println("only d");
}

This can be disabled by adding a comment of 'fall through' on the line before the case statement that can be fallen into.

Similar to spotless, checkstyle checks can be disabled using CHECKSTYLE.OFF: <Check> and CHECKSTYLE.ON: <Check> comment pairs. e.g.

public void check() {
    // CHECKSTYLE.OFF: NeedBraces - You cannot tell me what to do
    if (false) return;
    // CHECKSTYLE.ON: NeedBraces
}

However checkstyle additionally supports using the @SuppressWarnings annotation

@SuppressWarnings({ "checkstyle:NeedBraces", "checkstyle:MethodName", "checkstyle:DeclarationOrder" })
public class MyClass {
    public void BAD_METHOD_NAME() {
        if (true) return;
    }
    
    public int value;
}