Google Java Style Guide | Generated by AI

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1. Source File Basics

• File Naming:
  • Source files are named with the case-sensitive name of the top-level class they contain
  • Files must use UTF-8 encoding
  • Special characters in file names are discouraged

2. Source File Structure

Source File Organization

1. Package statement
2. Import statements
3. Exactly one top-level class

Import Statement Rules

• No wildcard imports
• Static imports are allowed
• Imports are organized in a specific order:
  • All static imports
  • All non-static imports
  • Imports within each group are alphabetized

3. Formatting Guidelines

Indentation and Braces

• Use 2 spaces for indentation (not tabs)
• Braces are used with if, else, for, do, and while statements, even for single-line blocks
• K&R style of brace placement is recommended

  public void method() {
    if (condition) {
      // Code block
    }
  }
  

Line Length and Wrapping

• Maximum line length is 100 characters
• Line breaks are preferred at higher-level syntax breaks
• When breaking method call chains, the break occurs before the .

4. Naming Conventions

General Rules

• Packages: Lowercase, no underscores
• Classes: UpperCamelCase
• Methods: lowerCamelCase
• Constants: UPPER_SNAKE_CASE
• Non-constant Fields: lowerCamelCase
• Parameters: lowerCamelCase
• Local Variables: lowerCamelCase

Specific Naming Practices

• Avoid abbreviations
• Exception names must end with Exception
• Test classes are named TestClassName

5. Programming Practices

Java Language Rules

• Exceptions:
  • Catch specific exceptions
  • Avoid empty catch blocks
  • Always include a detailed error message
• Final Keyword:
  • Use final for method parameters
  • Prefer immutable objects
• Annotations:
  • @Override is mandatory for overriding methods
  • Use standard annotations appropriately

Code Structure

• Prefer composition over inheritance
• Keep methods short and focused
• One statement per line
• Avoid deep nesting of conditionals

6. Comments and Documentation

Javadoc Guidelines

• All public classes and methods must have Javadoc
• Javadoc comments start with /**
• Include description, parameters, return values, and exceptions
• Use @param, @return, @throws tags

Inline Comments

• Use sparingly
• Explain “why”, not “what”
• Keep comments concise and meaningful

7. Version Control Considerations

• Avoid committing commented-out code
• Use version control system features instead of code comments for tracking changes

8. Performance Considerations

• Prefer enhanced for loops
• Use StringBuilder for string concatenation
• Close resources using try-with-resources
• Avoid creating unnecessary objects

9. Testing Principles

• Write unit tests
• Aim for high code coverage
• Use JUnit for testing
• Mock external dependencies
• Test edge cases and error conditions

10. Additional Tools

• Google provides a Java formatter and static analysis tools
• CheckStyle and Error Prone can be used to enforce style guidelines

Conclusion

The Google Java Style Guide provides a comprehensive set of guidelines to ensure consistent, readable, and maintainable Java code across projects.

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