Checkstyle defines a set of available modules, each of which provides rules checking with a configurable level of strictness (mandatory, optional...). Each rule can raise notifications, warnings, and errors. For example, checkstyle can examine: * Javadoc comments for classes, attributes and methods; * Naming conventions of attributes and methods; * Limit of the number of function parameters, line lengths; * Presence of mandatory headers; * The use of packets imports, of classes, of scope modifiers and of instructions blocks; * The spaces between some characters; * The good practices of class construction; * Duplicated code sections;[2] * Multiple complexity measurements, among which expressions.

* Built-in support for Google Android, Spring, Hibernate, Eclipse plug-ins, TDD, JDBC, EJBs, and more (mobile, embedded, Java EE...) * Integrates with Parasoft SOAtest for end-to-end functional and load testing for web, SOA, and cloud development. * Exposes runtime defects that occur as the application is exercised by unit, manual, or scripted tests–including race conditions, exceptions, resource leaks, and security attack vulnerabilities * Without requiring execution, identifies execution paths that can trigger runtime defects * Checks compliance to configurable sets of over 1000 built-in static analysis rules for Java * Provides templates for OWASP Top 10, CWE-SANS Top 25, PCI DSS, and other security static standards * Allows easy GUI-based customization of built-in rules * Identifies and prevents concurrency defects such as deadlocks, race conditions, missed notification, infinite loops, data corruption other threading problems * Automatically creates robust low-noise regression test suites–even for large code bases * Execute tests created in any open-format unit testing tool, including out-of-the-box support for JUnit- and TestNG– based testsIntegrates and extends manually-written unit test cases * Continuously executes the test suite to identify regressions and unexpected side effects * Performs runtime error detection as tests execute * Parameterizes test cases for use with varied, controlled test input values (runtime-generated, user-defined, or from data sources) * Monitors test coverage with multiple metrics * Tracks code coverage from manual tests and test scripts * Steps through tests with the debugger * Tests individual methods, classes, or large, complex applications * Calculates metrics such as Inheritance Depth, Lack Of Cohesion, Cyclomatic Complexity, Nested Blocks Depth, Number Of Children * Identifies duplicate and unused code * Shares test settings and files team-wide or organization-wide * Generates HTML, PDF, XML, and custom reports - Tracks how test results and code quality change over time - Provides GUI (interactive) and command-line (batch) mode