ParameterName

Since Checkstyle 3.0

Description

Checks that method parameter names conform to a specified pattern. By using accessModifiers property it is possible to specify different formats for methods at different visibility levels.

To validate catch parameters please use CatchParameterName .

To validate lambda parameters please use LambdaParameterName .

Properties

name	description	type	default value	since
accessModifiers	Access modifiers of methods where parameters are checked.	AccessModifierOption[]	`public, protected, package, private`	7.5
format	Sets the pattern to match valid identifiers.	Pattern	`"^[a-z][a-zA-Z0-9]*$"`	3.0
ignoreOverridden	Allows to skip methods with Override annotation from validation.	boolean	`false`	6.12.1

Examples

To configure the check:


<module name="Checker">
  <module name="TreeWalker">
    <module name="ParameterName"/>
  </module>
</module>

Code Example:


class Example1 {
  void method1(int v1) {}
  void method2(int V2) {} // violation
}

An example of how to configure the check for names that begin with a lower case letter, followed by letters, digits, and underscores:


<module name="Checker">
  <module name="TreeWalker">
    <module name="ParameterName">
      <property name="format" value="^[a-z][_a-zA-Z0-9]+$"/>
    </module>
  </module>
</module>

Code Example:


class Example2 {
  void method1(int v1) {}
  void method2(int v_2) {}
  void method3(int V3) {} // violation
}

An example of how to configure the check to skip methods with Override annotation from validation:


<module name="Checker">
  <module name="TreeWalker">
    <module name="ParameterName">
      <property name="ignoreOverridden" value="true"/>
    </module>
  </module>
</module>

Code Example:


class Example3 {
  void method1(int v1) {}
  void method2(int V2) {} // violation
  @Override
  public boolean equals(Object V3) { // OK
    return true;
  }
}

An example of how to configure the check for names that begin with a lower case letter, followed by letters and digits is:


<module name="Checker">
  <module name="TreeWalker">
    <module name="ParameterName">
      <property name="format" value="^[a-z][a-zA-Z0-9]+$"/>
    </module>
  </module>
</module>

Code Example:


class Example4 {
  void method1(int v1) {}
  void method2(int v_2) {} // violation
  void method3(int V3) {} // violation
}

The following configuration checks that the parameters always start with two lowercase characters and, in addition, that public method parameters cannot be one character long:


<module name="Checker">
  <module name="TreeWalker">
    <module name="ParameterName">
      <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
      <property name="accessModifiers" value="protected, package, private"/>
      <message key="name.invalidPattern"
        value="Parameter name ''{0}'' must match pattern ''{1}''"/>
    </module>
    <module name="ParameterName">
      <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$"/>
      <property name="accessModifiers" value="public"/>
      <message key="name.invalidPattern"
        value="Parameter name ''{0}'' must match pattern ''{1}''"/>
    </module>
  </module>
</module>

Code Example:


class Example5 {
  void fn1(int v1) {}
  protected void fn2(int V2) {} // violation "Parameter name 'V2' must match pattern"
  private void fn3(int a) {}
  public void fn4(int b) {} // violation "Parameter name 'b' must match pattern"
}

Example of Usage

Violation Messages

name.invalidPattern

All messages can be customized if the default message doesn't suit you. Please see the documentation to learn how to.

Package

com.puppycrawl.tools.checkstyle.checks.naming

Parent Module

TreeWalker