MethodNameCheck.java
////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2021 the original author or authors.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
////////////////////////////////////////////////////////////////////////////////
package com.puppycrawl.tools.checkstyle.checks.naming;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import com.puppycrawl.tools.checkstyle.utils.AnnotationUtil;
/**
* <p>
* Checks that method names conform to a specified pattern.
* </p>
*
* <p>Also, checks if a method name has the same name as the residing class.
* The default is false (it is not allowed). It is legal in Java to have
* method with the same name as a class. As long as a return type is specified
* it is a method and not a constructor which it could be easily confused as.
* Does not check-style the name of an overridden methods because the developer does not
* have a choice in renaming such methods.
* </p>
*
* <ul>
* <li>
* Property {@code format} - Specifies valid identifiers.
* Type is {@code java.util.regex.Pattern}.
* Default value is {@code "^[a-z][a-zA-Z0-9]*$"}.
* </li>
* <li>
* Property {@code allowClassName} - Controls whether to allow a method name to have the same name
* as the residing class name. This is not to be confused with a constructor. An easy mistake is
* to place a return type on a constructor declaration which turns it into a method. For example:
* <pre>
* class MyClass {
* public void MyClass() {} //this is a method
* public MyClass() {} //this is a constructor
* }
* </pre>
* Type is {@code boolean}.
* Default value is {@code false}.
* </li>
* <li>
* Property {@code applyToPublic} - Controls whether to apply the check to public member.
* Type is {@code boolean}.
* Default value is {@code true}.
* </li>
* <li>
* Property {@code applyToProtected} - Controls whether to apply the check to protected member.
* Type is {@code boolean}.
* Default value is {@code true}.
* </li>
* <li>
* Property {@code applyToPackage} - Controls whether to apply the check to package-private member.
* Type is {@code boolean}.
* Default value is {@code true}.
* </li>
* <li>
* Property {@code applyToPrivate} - Controls whether to apply the check to private member.
* Type is {@code boolean}.
* Default value is {@code true}.
* </li>
* </ul>
*
* <p>
* To configure the check:
* </p>
* <pre>
* <module name="MethodName"/>
* </pre>
* <p>Code Example:</p>
* <pre>
* class MyClass {
* public void firstMethod1() {} // OK
* protected void secondMethod() {} // OK
* private void ThirdMethod() {} // violation, method name must match to the
* // default pattern '^[a-z][a-zA-Z0-9]*$'
* public void fourth_Method4() {} // violation, method name must match to the
* // default pattern '^[a-z][a-zA-Z0-9]*$'
* }
* </pre>
* <p>
* An example of how to configure the check for names that begin with
* a lower case letter, followed by letters, digits, and underscores is:
* </p>
* <pre>
* <module name="MethodName">
* <property name="format" value="^[a-z](_?[a-zA-Z0-9]+)*$"/>
* </module>
* </pre>
* <p>Code Example:</p>
* <pre>
* class MyClass {
* public void myMethod() {} // OK
* public void MyMethod() {} // violation, name "MyMethod"
* // should match the pattern "^[a-z](_?[a-zA-Z0-9]+)*$"
* }
* </pre>
* <p>
* An example of how to configure the check to allow method names to be equal to the
* residing class name is:
* </p>
* <pre>
* <module name="MethodName">
* <property name="format" value="^[a-zA-Z](_?[a-zA-Z0-9]+)*$"/>
* <property name="allowClassName" value="true"/>
* </module>
* </pre>
* <p>Code Example:</p>
* <pre>
* class MyClass {
* public MyClass() {} // OK
* public void MyClass() {} // OK, method Name 'MyClass' is allowed to be
* // equal to the enclosing class name
* }
* </pre>
* <p>
* An example of how to configure the check to disallow method names to be equal to the
* residing class name is:
* </p>
* <pre>
* <module name="MethodName">
* <property name="format" value="^[a-zA-Z](_?[a-zA-Z0-9]+)*$"/>
* <property name="allowClassName" value="false"/>
* </module>
* </pre>
* <p>Code Example:</p>
* <pre>
* class MyClass {
* public MyClass() {} // OK
* public void MyClass() {} // violation, method Name 'MyClass' must not
* // equal the enclosing class name
* }
* </pre>
* <p>
* An example of how to suppress the check to public and protected methods:
* </p>
* <pre>
* <module name="MethodName">
* <property name="format" value="^[a-z](_?[a-zA-Z0-9]+)*$"/>
* <property name="applyToPublic" value="false"/>
* <property name="applyToProtected" value="false"/>
* </module>
* </pre>
* <p>Code Example:</p>
* <pre>
* class MyClass {
* public void FirstMethod() {} // OK
* protected void SecondMethod() {} // OK
* private void ThirdMethod() {} // violation, name 'ThirdMethod' must match
* // pattern '^[a-z](_?[a-zA-Z0-9]+)*$'
* void FourthMethod() {} // violation, name 'FourthMethod' must match
* // pattern '^[a-z](_?[a-zA-Z0-9]+)*$'
* }
* </pre>
* <p>
* Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
* </p>
* <p>
* Violation Message Keys:
* </p>
* <ul>
* <li>
* {@code method.name.equals.class.name}
* </li>
* <li>
* {@code name.invalidPattern}
* </li>
* </ul>
*
* @since 3.0
*/
public class MethodNameCheck
extends AbstractAccessControlNameCheck {
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_KEY = "method.name.equals.class.name";
/**
* {@link Override Override} annotation name.
*/
private static final String OVERRIDE = "Override";
/**
* Canonical {@link Override Override} annotation name.
*/
private static final String CANONICAL_OVERRIDE = "java.lang." + OVERRIDE;
/**
* Controls whether to allow a method name to have the same name as the residing class name.
* This is not to be confused with a constructor. An easy mistake is to place a return type on
* a constructor declaration which turns it into a method. For example:
* <pre>
* class MyClass {
* public void MyClass() {} //this is a method
* public MyClass() {} //this is a constructor
* }
* </pre>
*/
private boolean allowClassName;
/** Creates a new {@code MethodNameCheck} instance. */
public MethodNameCheck() {
super("^[a-z][a-zA-Z0-9]*$");
}
@Override
public int[] getDefaultTokens() {
return getRequiredTokens();
}
@Override
public int[] getAcceptableTokens() {
return getRequiredTokens();
}
@Override
public int[] getRequiredTokens() {
return new int[] {TokenTypes.METHOD_DEF, };
}
@Override
public void visitToken(DetailAST ast) {
if (!AnnotationUtil.containsAnnotation(ast, OVERRIDE)
&& !AnnotationUtil.containsAnnotation(ast, CANONICAL_OVERRIDE)) {
// Will check the name against the format.
super.visitToken(ast);
}
if (!allowClassName) {
final DetailAST method =
ast.findFirstToken(TokenTypes.IDENT);
// in all cases this will be the classDef type except anon inner
// with anon inner classes this will be the Literal_New keyword
final DetailAST classDefOrNew = ast.getParent().getParent();
final DetailAST classIdent =
classDefOrNew.findFirstToken(TokenTypes.IDENT);
// Following logic is to handle when a classIdent can not be
// found. This is when you have a Literal_New keyword followed
// a DOT, which is when you have:
// new Outclass.InnerInterface(x) { ... }
// Such a rare case, will not have the logic to handle parsing
// down the tree looking for the first ident.
if (classIdent != null
&& method.getText().equals(classIdent.getText())) {
log(method, MSG_KEY, method.getText());
}
}
}
/**
* Setter to controls whether to allow a method name to have the same name as the residing
* class name. This is not to be confused with a constructor. An easy mistake is to place
* a return type on a constructor declaration which turns it into a method. For example:
* <pre>
* class MyClass {
* public void MyClass() {} //this is a method
* public MyClass() {} //this is a constructor
* }
* </pre>
*
* @param allowClassName true to allow false to disallow
*/
public void setAllowClassName(boolean allowClassName) {
this.allowClassName = allowClassName;
}
}