# Miscellaneous Checks

## GenericIllegalRegexp

#### Description

A generic check for code problems - the user can search for any pattern. This is similar to a recursive grep, only that it's integrated in checkstyle.

Rationale: This check can be used to prototype checks and to find common bad practice such as calling ex.printStacktrace(), System.out.println(), System.exit(), etc.

#### Properties

name | description | type | default value
--- | --- | --- | ---
format | illegal pattern | regular expression | ^$ (empty)
ignoreCase | Controls whether to ignore case when searching. | Boolean | false
ignoreComments | Controls whether to ignore text in comments when searching. | Boolean | false
message | message which is used to notify about violations, if empty then default(hard-coded) message is used. | String | ""(empty)

#### Examples

To configure the check for calls to System.out.println:

    <module name="GenericIllegalRegexp">
        <!-- . matches any character, so we need to
             escape it and use \. to match dots. -->
        <property name="format" value="System\.out\.println"/>
    </module>

To configure the check to find trailing whitespace at the end of a line:

    <module name="GenericIllegalRegexp">
        <!-- \s matches whitespace character, $ matches end of line. -->
        <property name="format" value="\s$"/>
    </module>

To configure the check to find case-insensitive occurrences of "debug":

    <module name="GenericIllegalRegexp">
        <property name="format" value="debug"/>
        <property name="ignoreCase" value="true"/>
    </module>

#### Package

com.puppycrawl.tools.checkstyle.checks

#### Parent Module

TreeWalker

## NewlineAtEndOfFile

#### Description

Checks whether files end with a new line.

Rationale: Any source files and text files in general should end with a newline character, especially when using SCM systems such as CVS. CVS will even print a warning when it encounters a file that doesn't end with a newline.

#### Properties

name | description | type | default value
--- | --- | --- | ---
lineSeparator | type of line separator | One of "system" (system default), "crlf" (Windows-style), "cr" (Mac-style) and "lf" (Unix-style) | system default

#### Examples

To configure the check:

    <module name="NewlineAtEndOfFile"/>

To configure the check to always use Unix-style line separators:

    <module name="NewlineAtEndOfFile">
        <property name="lineSeparator" value="lf"/>
    </module>

#### Package

com.puppycrawl.tools.checkstyle.checks

#### Parent Module

Checker

## TodoComment

#### Description

A check for TODO: comments. Actually it is a generic regular expression matcher on Java comments. To check for other patterns in Java comments, set property format.

#### Properties

name | description | type | default value
--- | --- | --- | ---
format | pattern to check | regular expression | TODO:

#### Notes

Using TODO: comments is a great way to keep track of tasks that need to be done. Having them reported by Checkstyle makes it very hard to forget about them.

#### Examples

To configure the check:

    <module name="TodoComment"/>

To configure the check for comments that contain WARNING:

    <module name="TodoComment">
        <property name="format" value="WARNING"/>
    </module>

#### Package

com.puppycrawl.tools.checkstyle.checks

#### Parent Module

TreeWalker

## Translation

#### Description

A FileSetCheck that ensures the correct translation of code by checking property files for consistency regarding their keys. Two property files describing one and the same context are consistent if they contain the same keys.

Consider the following properties file in the same directory:

          #messages.properties
          hello=Hello
          cancel=Cancel

          #messages_de.properties
          hell=Hallo
          ok=OK

The Translation check will find the typo in the german hello key, the missing ok key in the default resource file and the missing cancel key in the german resource file:

          messages_de.properties: Key 'hello' missing.
          messages_de.properties: Key 'cancel' missing.
          messages.properties: Key 'hell' missing.
          messages.properties: Key 'ok' missing.

#### Properties

name | description | type | default value
--- | --- | --- | ---
fileExtensions | file type extension to identify translation files. Setting this property is typically only required if your translation files are preprocessed and the original files do not have the extension .properties | String Set | properties

#### Example

To configure the check:

    <module name="Translation"/>

#### Package

com.puppycrawl.tools.checkstyle.checks

#### Parent Module

Checker

## UncommentedMain

#### Description

Checks for uncommented main() methods (debugging leftovers).

Rationale: A main() method is often used for debug puposes. When debugging is finished, developers often forget to remove the method, which changes the API and increases the size of the resulting class/jar file. With the exception of the real program entry points, all main() methods should be removed/commented out of the sources.

#### Properties

name | description | type | default value
--- | --- | --- | ---
excludedClasses | pattern for qualified names of classes which are allowed to have a main method. | regular expression | ^$

#### Examples

To configure the check:

    <module name="UncommentedMain"/>

To configure the check to allow main method for all classes with "Main" name:

    <module name="UncommentedMain">
        <property name="excludedClasses" value="\.Main$"/>
    </module>

#### Package

com.puppycrawl.tools.checkstyle.checks

#### Parent Module

TreeWalker

## UpperEll

#### Description

Checks that long constants are defined with an upper ell. That is ' L' and not 'l'. This is in accordance to the Java Language Specification, Section 3.10.1.

Rationale: The letter l looks a lot like 1.

#### Examples

To configure the check:

    <module name="UpperEll"/>

#### Package

com.puppycrawl.tools.checkstyle.checks

#### Parent Module

TreeWalker

## ArrayTypeStyle

#### Description

Checks the style of array type definitions. Some like Java-style: `public static void main(String[] args)` and some like C-style: public static void main(String args[])

#### Properties

name | description | type | default value
--- | --- | --- | ---
javaStyle | Controls whether to enforce Java style (true) or C style (false). | Boolean | true

#### Examples

To configure the check to enforce Java style:

    <module name="ArrayTypeStyle"/>

To configure the check to enforce C style:

    <module name="ArrayTypeStyle">
        <property name="javaStyle" value="false"/>
    </module>

#### Package

com.puppycrawl.tools.checkstyle.checks

#### Parent Module

TreeWalker

## FinalParameters

#### Description

Check that method/constructor/catch block parameters are final. Interface methods are not checked - the final keyword does not make sense for interface method parameters as there is no code that could modify the parameter.

Rationale: Changing the value of parameters during the execution of the method's algorithm can be confusing and should be avoided. A great way to let the Java compiler prevent this coding style is to declare parameters final.

#### Properties

name | description | type | default value
--- | --- | --- | ---
tokens | blocks to check | subset of tokens METHOD_DEF, CTOR_DEF, LITERAL_CATCH | METHOD_DEF, CTOR_DEF

#### Examples

To configure the check to enforce final parameters for methods and constructors:

    <module name="FinalParameters"/>

To configure the check to enforce final parameters only for constructors:

    <module name="FinalParameters">
        <property name="tokens" value="CTOR_DEF"/>
    </module>

#### Package

com.puppycrawl.tools.checkstyle.checks

#### Parent Module

TreeWalker

## DescendantToken

#### Description

Checks for restricted tokens beneath other tokens.

WARNING: This is a very powerful and flexible check, but, at the same time, it is low level and very implementation dependent because its results depend on the grammar we use to build abstract syntax trees. Thus we recomend using other checks when they provide the desired funcionality. All in all, this check just works on the level of an abstract tree and knows nothing about language structures.

#### Properties

name | description | type | default value
--- | --- | --- | ---
tokens | token types to check | subset of tokens declared in TokenTypes | empty set
limitedTokens | set of tokens with limited occurances as descendants | subset of tokens declared in TokenTypes | empty set
minimumDepth | the mimimum depth for descendant counts | Integer | 0
maximumDepth | the maximum depth for descendant counts | Integer | java.lang.Integer.MAX_VALUE
minimumNumber | a minimum count for descendants | Integer | 0
maximumNumber | a maximum count for descendants | Integer | java.lang.Integer.MAX_VALUE
minimumMessage | error message when minimum count not reached | String | "descendant.token.min"
maximumMessage | error message when maximum count exceeded | String | "descendant.token.max"

#### Examples

            String literal equality check:
            <module name="DescendantToken">
                <property name="tokens" value="EQUAL,NOT_EQUAL"/>
                <property name="limitedTokens" value="STRING_LITERAL"/>
                <property name="maximumNumber" value="0"/>
                <property name="maximumDepth" value="1"/>
            </module>

            Switch with no default:
            <module name="DescendantToken">
                <property name="tokens" value="LITERAL_SWITCH"/>
                <property name="maximumDepth" value="2"/>
                <property name="limitedTokens" value="LITERAL_DEFAULT"/>
                <property name="minimumNumber" value="1"/>
            </module>

            Assert statement may have side effects (formatted for browser display):
            <module name="DescendantToken">
                <property name="tokens" value="LITERAL_ASSERT"/>
                <property name="limitedTokens" value="ASSIGN,DEC,INC,POST_DEC,
                    POST_INC,PLUS_ASSIGN,MINUS_ASSIGN,STAR_ASSIGN,DIV_ASSIGN,MOD_ASSIGN,
                    BSR_ASSIGN,SR_ASSIGN,SL_ASSIGN,BAND_ASSIGN,BXOR_ASSIGN,BOR_ASSIGN,
                    METHOD_CALL"/>
                <property name="maximumNumber" value="0"/>
            </module>

            Initialiser in for performs no setup (use while instead?):
            <module name="DescendantToken">
                <property name="tokens" value="FOR_INIT"/>
                <property name="limitedTokens" value="EXPR"/>
                <property name="minimumNumber" value="1"/>
            </module>

            Condition in for performs no check:
            <module name="DescendantToken">
                <property name="tokens" value="FOR_CONDITION"/>
                <property name="limitedTokens" value="EXPR"/>
                <property name="minimumNumber" value="1"/>
            </module>

            Switch within switch:
            <module name="DescendantToken">
                <property name="tokens" value="LITERAL_SWITCH"/>
                <property name="limitedTokens" value="LITERAL_SWITCH"/>
                <property name="maximumNumber" value="0"/>
                <property name="minimumDepth" value="1"/>
            </module>

            Return from within a catch or finally block:
            <module name="DescendantToken">
                <property name="tokens" value="LITERAL_FINALLY,LITERAL_CATCH"/>
                <property name="limitedTokens" value="LITERAL_RETURN"/>
                <property name="maximumNumber" value="0"/>
            </module>

            Try within catch or finally block:
            <module name="DescendantToken">
                <property name="tokens" value="LITERAL_CATCH,LITERAL_FINALLY"/>
                <property name="limitedTokens" value="LITERAL_TRY"/>
                <property name="maximumNumber" value="0"/>
            </module>

            Too many cases within a switch:
            <module name="DescendantToken">
                <property name="tokens" value="LITERAL_SWITCH"/>
                <property name="limitedTokens" value="LITERAL_CASE"/>
                <property name="maximumDepth" value="2"/>
                <property name="maximumNumber" value="10"/>
            </module>

            Too many local variables within a method:
            <module name="DescendantToken">
                <property name="tokens" value="METHOD_DEF"/>
                <property name="limitedTokens" value="VARIABLE_DEF"/>
                <property name="maximumDepth" value="2"/>
                <property name="maximumNumber" value="10"/>
            </module>

            Too many returns from within a method:
            <module name="DescendantToken">
                <property name="tokens" value="METHOD_DEF"/>
                <property name="limitedTokens" value="LITERAL_RETURN"/>
                <property name="maximumNumber" value="3"/>
            </module>

            Too many fields within an interface:
            <module name="DescendantToken">
                <property name="tokens" value="INTERFACE_DEF"/>
                <property name="limitedTokens" value="VARIABLE_DEF"/>
                <property name="maximumDepth" value="2"/>
                <property name="maximumNumber" value="0"/>
            </module>

            Limit the number of exceptions a method can throw:
            <module name="DescendantToken">
                <property name="tokens" value="LITERAL_THROWS"/>
                <property name="limitedTokens" value="IDENT"/>
                <property name="maximumNumber" value="1"/>
            </module>

            Limit the number of expressions in a method:
            <module name="DescendantToken">
                <property name="tokens" value="METHOD_DEF"/>
                <property name="limitedTokens" value="EXPR"/>
                <property name="maximumNumber" value="200"/>
            </module>

            Disallow empty statements:
            <module name="DescendantToken">
                <property name="tokens" value="EMPTY_STAT"/>
                <property name="limitedTokens" value="EMPTY_STAT"/>
                <property name="maximumNumber" value="0"/>
                <property name="maximumDepth" value="0"/>
                <property name="maximumMessage"
                    value="Empty statement is not allowed."/>
            </module>

            Too many fields within a class:
            <module name="DescendantToken">
                <property name="tokens" value="CLASS_DEF"/>
                <property name="limitedTokens" value="VARIABLE_DEF"/>
                <property name="maximumDepth" value="2"/>
                <property name="maximumNumber" value="10"/>
            </module>

#### Package

com.puppycrawl.tools.checkstyle.checks

#### Parent Module

TreeWalker

Indentation

## Indentation

#### Description

Checks correct indentation of Java Code.

The basic idea behind this is that while pretty printers are sometimes convienent for bulk reformats of legacy code, they often either aren't configurable enough or just can't anticipate how format should be done. Sometimes this is personal preference, other times it is practical experience. In any case, this check should just ensure that a minimal set of indentation rules are followed.

#### Properties

name | description | type | default value
--- | --- | --- | ---
basicOffset | how many spaces to use for new indentation level | Integer | 4
braceAdjustment | how far brace should be indented when on next line | Integer | 0
caseIndent | how much to indent a case label | Integer | 4

#### Examples

To configure the check:

    <module name="Indentation"/>

To configure the check to enforce indentation style recommended by Sun:

    <module name="Indentation">
        <property name="caseIndent" value="0"/>
    </module>

#### Package

com.puppycrawl.tools.checkstyle.checks.indentation

#### Parent Module

TreeWalker

TrailingComment

## TrailingComment

#### Description

The check to ensure that requires that comments be the only thing on a line. For the case of // comments that means that the only thing that should precede it is whitespace. It doesn't check comments if they do not end line, i.e. it accept the following: `Thread.sleep( 10 <some comment here> );` Format property is intended to deal with the "} // while" example.

Rationale: Steve McConnel in "Code Complete" suggests that endline comments are a bad practice. An end line comment would be one that is on the same line as actual code. For example:

           a = b + c;      // Some insightful comment
           d = e / f;        // Another comment for this line

Quoting "Code Complete" for the justfication:

- "The comments have to be aligned so that they do not interfere with the visual structure of the code. If you don't align them neatly, they'll make your listing look like it's been through a washing machine."
- "Endline comments tend to be hard to format...It takes time to align them. Such time is not spent learning more about the code; it's dedicated solely to the tedious task of pressing the spacebar or tab key."
- "Endline comments are also hard to maintain. If the code on any line containing an endline comment grows, it bumps the comment farther out, and all the other endline comments will have to bumped out to match. Styles that are hard to maintain aren't maintained...."
- "Endline comments also tend to be cryptic. The right side of the line doesn't offer much room and the desire to keep the comment on one line means the comment must be short. Work then goes into making the line as short as possible instead of as clear as possible. The comment usually ends up as cryptic as possible...."
- "A systemic problem with endline comments is that it's hard to write a meaningful comment for one line of code. Most endline comments just repeat the line of code, which hurts more than it helps."

His comments on being hard to maintain when the size of the line changes are even more important in the age of automated refactorings.

#### Properties

name | description | type | default value
--- | --- | --- | ---
format | pattern for string allowed before comment. | regular expression | ^[\\s\\}\\);]*$

#### Examples

To configure the check:

    <module name="TrailingComment"/>

To configure the check so it enforces only comment on a line:

    <module name="TrailingComment">
        <property name="format" value="^\\s*$"/>
     </module>

#### Package

com.puppycrawl.tools.checkstyle.checks.indentation

#### Parent Module

TreeWalker

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Copyright © 2002-2003 Oliver Burn. All rights Reserved.