### Run PMD Analysis (Linux/macOS)

Source: https://docs.pmd-code.org/latest/pmd_userdocs_installation.html

Example of running a PMD analysis on Java sources using the text format and a quickstart ruleset.

```shell
~ $ pmd check -f text -R rulesets/java/quickstart.xml src/main/java

.../src/main/java/com/me/RuleSet.java:123  These nested if statements could be combined
.../src/main/java/com/me/RuleSet.java:231  Useless parentheses.
.../src/main/java/com/me/RuleSet.java:232  Useless parentheses.
.../src/main/java/com/me/RuleSet.java:357  These nested if statements could be combined
.../src/main/java/com/me/RuleSetWriter.java:66     Avoid empty catch blocks

```

--------------------------------

### Install All Contributors CLI

Source: https://docs.pmd-code.org/latest/pmd_devdocs_contributing.html

Install the All Contributors CLI tool in the PMD top-level directory.

```bash
npm i
```

--------------------------------

### Run PMD Analysis (Windows)

Source: https://docs.pmd-code.org/latest/pmd_userdocs_installation.html

Example of running a PMD analysis on Java sources using the text format and a quickstart ruleset on Windows.

```batch
C:\> pmd.bat check -f text -R rulesets/java/quickstart.xml ..\..\src\main\java

...\src\main\java\com\me\RuleSet.java:123  These nested if statements could be combined
...\src\main\java\com\me\RuleSet.java:231  Useless parentheses.
...\src\main\java\com\me\RuleSet.java:232  Useless parentheses.
...\src\main\java\com\me\RuleSet.java:357  These nested if statements could be combined
...\src\main\java\com\me\RuleSetWriter.java:66     Avoid empty catch blocks

```

--------------------------------

### ApexDoc Example

Source: https://docs.pmd-code.org/latest/pmd_rules_apex_documentation.html

This example demonstrates a class and method with valid ApexDoc comments. It includes a main description and an @return tag for a non-void method.

```apex
/**
 * Hello World
 */
public class HelloWorld {
    /**
     * Bar
     * @return Bar
     */
    public Object bar() { return null; }
}
```

--------------------------------

### Install Bundles and Render Release Notes

Source: https://docs.pmd-code.org/latest/pmd_projectdocs_committers_releasing.html

Installs necessary Ruby gems for rendering release notes and then generates the release notes content. Ensure you are in the 'docs' directory before running.

```bash
cd docs
bundle config set --local path vendor/bundle
bundle install
NEW_RELEASE_NOTES=$(bundle exec render_release_notes.rb pages/release_notes.md | tail -n +6)
cd ..
```

--------------------------------

### Build Documentation with Bundler

Source: https://docs.pmd-code.org/latest/pmd_devdocs_writing_documentation.html

Commands to install dependencies, build the documentation, and serve it locally using Bundler.

```bash
# this is required only once, to download and install the dependencies
bundle install
# this builds the documentation under _site
bundle exec jekyll build
# this runs a local webserver as http://localhost:4005
bundle exec jekyll serve
```

--------------------------------

### Install pmdtester Gem

Source: https://docs.pmd-code.org/latest/pmd_devdocs_pmdtester.html

Installs the pmdtester gem, including pre-release versions. Ensure you have RubyGems installed.

```bash
gem install pmdtester --pre
```

--------------------------------

### Apex NcssConstructorCount Example

Source: https://docs.pmd-code.org/latest/pmd_rules_apex_design.html

An example constructor demonstrating the NCSS (Non-Commenting Source Statements) line count for the NcssConstructorCount rule.

```apex
public class Foo extends Bar {
    //this constructor only has 1 NCSS lines
    public Foo() {
        super();




        super.foo();
}
}
```

--------------------------------

### PMD Rule Reference Example

Source: https://docs.pmd-code.org/latest/pmd_rules_jsp_bestpractices.html

Shows how to reference a PMD rule in a configuration file. This is a common pattern for enabling specific rules.

```xml
<rule ref="category/jsp/bestpractices.xml/DontNestJsfInJstlIteration" />
```

```xml
<rule ref="category/jsp/bestpractices.xml/NoClassAttribute" />
```

```xml
<rule ref="category/jsp/bestpractices.xml/NoHtmlComments" />
```

```xml
<rule ref="category/jsp/bestpractices.xml/NoJspForward" />
```

--------------------------------

### Configure GuardLogStatement Rule

Source: https://docs.pmd-code.org/latest/pmd_rules_java_bestpractices.html

Example of how to reference the GuardLogStatement rule with default properties.

```xml
<rule ref="category/java/bestpractices.xml/GuardLogStatement" />
```

--------------------------------

### Launch PMD Rule Designer on Linux/macOS

Source: https://docs.pmd-code.org/latest/pmd_userdocs_extending_your_first_rule.html

Use this command to start the PMD Rule Designer on Linux or macOS systems.

```bash
~ $ pmd designer
```

--------------------------------

### Configure AvoidBranchingStatementAsLastInLoop Rule (XML)

Source: https://docs.pmd-code.org/latest/pmd_rules_java_errorprone.html

This example shows how to reference the rule with default properties and how to customize it by specifying properties for loop types.

```xml
<rule ref="category/java/errorprone.xml/AvoidBranchingStatementAsLastInLoop" />
```

```xml
<rule ref="category/java/errorprone.xml/AvoidBranchingStatementAsLastInLoop">
    <properties>
        <property name="checkBreakLoopTypes" value="for,do,while" />
        <property name="checkContinueLoopTypes" value="for,do,while" />
        <property name="checkReturnLoopTypes" value="for,do,while" />
    </properties>
</rule>
```

--------------------------------

### Configure Apex Formal Parameter Naming Conventions

Source: https://docs.pmd-code.org/latest/pmd_rules_apex_codestyle.html

Example of how to reference the FormalParameterNamingConventions rule with default properties.

```xml
<rule ref="category/apex/codestyle.xml/FormalParameterNamingConventions" />
```

--------------------------------

### Apex StdCyclomaticComplexity Rule Example

Source: https://docs.pmd-code.org/latest/pmd_rules_apex_design.html

This example demonstrates a method with high cyclomatic complexity due to multiple decision points like if, else if, while, for, and switch cases. Use this rule to identify overly complex methods.

```apex
// This has a Cyclomatic Complexity = 12
public class Foo {
1   public void example() {
2   if (a == b || (c == d && e == f)) {
3       if (a1 == b1) {
            fiddle();
4       } else if a2 == b2) {
            fiddle();
        }  else {
            fiddle();
        }
5   } else if (c == d) {
6       while (c == d) {
            fiddle();
        }
7   } else if (e == f) {
8       for (int n = 0; n < h; n++) {
            fiddle();
        }
    } else {
        switch (z) {
9           case 1:
                fiddle();
                break;
10          case 2:
                fiddle();
                break;
11          case 3:
                fiddle();
                break;
12          default:
                fiddle();
                break;
        }
    }
}


```

--------------------------------

### Java AST Node Structure Example

Source: https://docs.pmd-code.org/latest/pmd_userdocs_extending_writing_rules_intro.html

Illustrates the AST structure for a simple Java class declaration.

```text
class Foo extends Object {

}

```

```text
|  ```
└─ CompilationUnit
   └─ TypeDeclaration
      └─ ClassDeclaration "Foo"
         ├─ ModifierList
         ├─ ExtendsList
         │  └─ ClassType "Object"
         └─ ClassBody

```

--------------------------------

### Example Usage of pmd:startLine()

Source: https://docs.pmd-code.org/latest/pmd_userdocs_extending_writing_xpath_rules.html

This XPath expression selects `<b>` nodes that start after the fifth line of the source file. It showcases the pmd:startLine() function to retrieve the starting line number of a node.

```xpath
//b[pmd:startLine(.) > 5]
```

--------------------------------

### Initial PMD Build with Maven

Source: https://docs.pmd-code.org/latest/pmd_devdocs_building_general.html

Perform an initial build of PMD using Maven to set up the environment and aid Maven IDE integration. This step downloads all dependencies and may take time.

```bash
cd pmd
./mvnw clean verify -DskipTests

```

--------------------------------

### Apex ExcessiveParameterList Example

Source: https://docs.pmd-code.org/latest/pmd_rules_apex_design.html

Demonstrates methods with too many parameters and a preferred approach using objects to group parameters.

```apex
public void addPerson(Integer birthYear, Integer birthMonth, Integer birthDate, Integer height, Integer weight, Integer ssn) {
    // ...
}
// preferred approach
public void addPerson(Date birthdate, BodyMeasurements measurements, int ssn) {
    // ...
}
```

--------------------------------

### Get start column of a node

Source: https://docs.pmd-code.org/latest/pmd_userdocs_extending_writing_xpath_rules.html

Use pmd:startColumn to find the column number where a node begins in the source file. Column numbers are 1-based and inclusive.

```xpath
//b[pmd:startColumn(.) = 1]
```

--------------------------------

### Example sfdx-project.json Configuration

Source: https://docs.pmd-code.org/latest/pmd_rules_apex_design.html

This configuration includes necessary settings for Apex development, such as package directories, namespace, and external package dependencies, which are important for accurate static analysis.

```json
{
    "packageDirectories": [
      {
        "path": "src",
        "default": true
      }
    ],
    "namespace": "my_namespace",
    "sfdcLoginUrl": "https://login.salesforce.com",
    "sourceApiVersion": "52.0",
    "plugins": {
        "dependencies": [
            {"namespace": "aa"}
        ]
    }
}

```

--------------------------------

### Build Documentation with Docker

Source: https://docs.pmd-code.org/latest/pmd_devdocs_writing_documentation.html

Commands to build a Docker image for PMD documentation and to build or serve the documentation using the Docker image.

```bash
# this is required only once to create a local docker image named "pmd-doc"
docker build --no-cache -t pmd-doc .
# this builds the documentation under _site
docker run --rm=true -v "$PWD:/src" pmd-doc build -H 0.0.0.0
# this runs a local webserver as http://localhost:4005
docker run --rm=true -v "$PWD:/src" -p 4005:4005 pmd-doc serve -H 0.0.0.0
```

--------------------------------

### Example Abstract Class

Source: https://docs.pmd-code.org/latest/pmd_rules_java_design.html

An example of an abstract class with fields but no methods, which could be flagged by the AbstractClassWithoutAnyMethod rule.

```java
public abstract class Example {
    String field;
    int otherField;
}


```

--------------------------------

### Uncommented Empty Constructor Example

Source: https://docs.pmd-code.org/latest/pmd_rules_java_documentation.html

Example of an empty constructor that should be commented to distinguish it from unintentional empty constructors.

```java
public Foo() {
  // This constructor is intentionally empty. Nothing special is needed here.
}
```

--------------------------------

### Full Ant Build File Example with Auxclasspath

Source: https://docs.pmd-code.org/latest/pmd_userdocs_tools_ant.html

A complete Ant build file demonstrating the PMD task with auxclasspath configuration. Ensure your project is compiled first.

```xml
<project name="MyProject" default="pmd" basedir=".">
    <property name="src" location="src"/>
    <property name="build" location="build"/>
    <path id="project.dependencies">
        <pathelement location="lib/third-party.jar"/>
        <pathelement location="lib/xyz.jar"/>
    </path>
    <path id="pmd.classpath">
        <fileset dir="/home/joe/pmd-bin-7.24.0/lib">
            <include name="*.jar"/>
        </fileset>
    </path>
    <taskdef name="pmd" classname="net.sourceforge.pmd.ant.PMDTask" classpathref="pmd.classpath" />
    
    <target name="init">
        <mkdir dir="${build}"/>
    </target>
    
    <target name="compile" depends="init">
        <javac srcdir="${src}" destdir="${build}" classpathref="project.dependencies"
            source="1.8" target="1.8" />
    </target>
    
    <target name="pmd" depends="compile">
        <pmd cacheLocation="${build}/pmd.cache">
            <auxclasspath>
                <pathelement location="${build}"/>
                <path refid="project.dependencies"/>
            </auxclasspath>
            <ruleset>rulesets/java/quickstart.xml</ruleset>
            <formatter type="html" toFile="${build}/pmd_report.html"/>
            <sourceLanguage name="java" version="1.8"/>
            <fileset dir="${src}">
                <include name="**/*.java"/>
            </fileset>
        </pmd>
    </target>
    
    <target name="clean">
        <delete dir="${build}"/>
    </target>
</project>
```

--------------------------------

### Apex ExcessivePublicCount Example

Source: https://docs.pmd-code.org/latest/pmd_rules_apex_design.html

An example class with numerous public attributes, methods, and properties, illustrating the ExcessivePublicCount rule.

```apex
public class Foo {
    public String value;
    public Bar something;
    public Variable var;
    // [... more more public attributes ...]

    public void doWork() {}
    public void doMoreWork() {}
    public void doWorkAgain() {}
    // [... more more public methods ...]

    public String property1 { get; set; }
    // [... more more public properties ...]
}
```

--------------------------------

### Uncommented Empty Method Body Example

Source: https://docs.pmd-code.org/latest/pmd_rules_java_documentation.html

Example of an empty method body that should be commented to distinguish it from unintentional empty methods.

```java
public void doSomething() {
}
```

--------------------------------

### Run Full Project Build

Source: https://docs.pmd-code.org/latest/pmd_projectdocs_committers_merging_pull_requests.html

Executes a clean build of the project, including all unit tests and checkstyle tests, using the Maven wrapper. The `-Pgenerate-rule-docs` profile ensures documentation checks are performed.

```bash
./mvnw clean verify -Pgenerate-rule-docs
```

--------------------------------

### Basic CPD Usage

Source: https://docs.pmd-code.org/latest/pmd_userdocs_cpd.html

Run CPD with minimum token count and source directory. Supports Linux/macOS and Windows.

```bash
~ $ pmd cpd --minimum-tokens 100 --dir src/main/java
```

```batch
C:\> pmd.bat cpd --minimum-tokens 100 --dir src\main\java
```

--------------------------------

### Detect JUnit setUp() without @Before annotation

Source: https://docs.pmd-code.org/latest/pmd_rules_java_bestpractices.html

This rule detects methods named 'setUp()' that are not annotated with @Before (JUnit 4), @BeforeEach/@BeforeAll (JUnit 5), or @BeforeMethod/@BeforeClass (TestNG). It assists in migrating from JUnit 3 conventions or enforcing consistent setup method naming.

```java
public class MyTest {
    public void setUp() {
        bad();
    }
}
public class MyTest2 {
    @Before public void setUp() {
        good();
    }
}
```

--------------------------------

### XML Report Example

Source: https://docs.pmd-code.org/latest/pmd_userdocs_report_formats.html

This is an example of a PMD report in XML format. It can be validated against the report_2_0_0.xsd schema. The 'encoding' property defaults to UTF-8.

```xml
<?xml version="1.0" encoding="UTF-8"?>
<pmd xmlns="http://pmd.sourceforge.net/report/2.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://pmd.sourceforge.net/report/2.0.0 https://pmd.github.io/schema/report_2_0_0.xsd"
    version="6.22.0" timestamp="2020-04-11T19:17:03.207">
<file name="/home/pmd/source/pmd-core/src/main/java/net/sourceforge/pmd/RuleContext.java">
<violation beginline="124" endline="125" begincolumn="9" endcolumn="111" rule="GuardLogStatement" ruleset="Best Practices" package="net.sourceforge.pmd" class="RuleContext" method="setSourceCodeFilename" externalInfoUrl="https://pmd.github.io/pmd-6.22.0/pmd_rules_java_bestpractices.html#guardlogstatement" priority="2">
Logger calls should be surrounded by log level guards.
</violation>
</file>
<file name="/home/pmd/source/pmd-core/src/main/java/net/sourceforge/pmd/benchmark/Benchmarker.java">
<violation beginline="58" endline="62" begincolumn="9" endcolumn="9" rule="ForLoopCanBeForeach" ruleset="Best Practices" package="net.sourceforge.pmd.benchmark" class="Benchmarker" method="findBooleanSwitch" externalInfoUrl="https://pmd.github.io/pmd-6.22.0/pmd_rules_java_bestpractices.html#forloopcanbeforeach" priority="3">
This for loop can be replaced by a foreach loop
</violation>
</file>
<error filename="/home/pmd/source/pmd-core/src/test/resources/net/sourceforge/pmd/cpd/files/file_with_ISO-8859-1_encoding.java" msg="PMDException: Error while parsing /home/pmd/source/pmd-core/src/test/resources/net/sourceforge/pmd/cpd/files/file_with_ISO-8859-1_encoding.java">
<![CDATA[net.sourceforge.pmd.PMDException: Error while parsing /home/pmd/source/pmd-core/src/test/resources/net/sourceforge/pmd/cpd/files/file_with_ISO-8859-1_encoding.java
    at net.sourceforge.pmd.SourceCodeProcessor.processSourceCodeWithoutCache(SourceCodeProcessor.java:110)
    at net.sourceforge.pmd.SourceCodeProcessor.processSourceCode(SourceCodeProcessor.java:89)
    at net.sourceforge.pmd.SourceCodeProcessor.processSourceCode(SourceCodeProcessor.java:51)
    at net.sourceforge.pmd.processor.PmdRunnable.call(PmdRunnable.java:78)
    at net.sourceforge.pmd.processor.PmdRunnable.call(PmdRunnable.java:24)
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
    at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
    at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: net.sourceforge.pmd.lang.java.ast.ParseException: Encountered " - " - " " at line 6, column 30.
Was expecting one of:
    "extends" ...
    "implements" ...
    "{" ...
    "<" ...
    
    at net.sourceforge.pmd.lang.java.ast.JavaParser.generateParseException(JavaParser.java:12713)
    at net.sourceforge.pmd.lang.java.ast.JavaParser.jj_consume_token(JavaParser.java:12597)
    at net.sourceforge.pmd.lang.java.ast.JavaParser.ClassOrInterfaceBody(JavaParser.java:1554)
    at net.sourceforge.pmd.lang.java.ast.JavaParser.ClassOrInterfaceDeclaration(JavaParser.java:732)
    at net.sourceforge.pmd.lang.java.ast.JavaParser.TypeDeclaration(JavaParser.java:639)
    at net.sourceforge.pmd.lang.java.ast.JavaParser.CompilationUnit(JavaParser.java:373)
    at net.sourceforge.pmd.lang.java.AbstractJavaParser.parse(AbstractJavaParser.java:62)
    at net.sourceforge.pmd.SourceCodeProcessor.parse(SourceCodeProcessor.java:121)
    at net.sourceforge.pmd.SourceCodeProcessor.processSource(SourceCodeProcessor.java:185)
    at net.sourceforge.pmd.SourceCodeProcessor.processSourceCodeWithoutCache(SourceCodeProcessor.java:107)
    ... 10 more
]]>
</error>
<suppressedviolation filename="/home/pmd/source/pmd-core/src/main/java/net/sourceforge/pmd/PMD.java" suppressiontype="@suppresswarnings" msg="Ensure that resources like this OutputStreamWriter object are closed after use" usermsg=""/>
<configerror rule="LoosePackageCoupling" msg="No packages or classes specified"/>
</pmd>
```

--------------------------------

### Build PMD Documentation with Jekyll

Source: https://docs.pmd-code.org/latest/pmd_devdocs_building_general.html

Build the PMD documentation site using Jekyll. Ensure you have installed the necessary Ruby gems first.

```bash
cd docs
bundle install # once
bundle exec jekyll build

```

--------------------------------

### Invalid JavaBean Example

Source: https://docs.pmd-code.org/latest/pmd_rules_java_design.html

This example demonstrates an invalid JavaBean due to a missing setter for the 'label' property and the absence of 'implements Serializable'.

```java
package org.example.beans;
public class MyBean {        // <-- bean is not serializable, missing "implements Serializable"
    private String label;    // <-- missing setter for property "label"

    public String getLabel() {
        return label;
    }
}
```

--------------------------------

### IntelliJ IDEA CLI Command for Single File

Source: https://docs.pmd-code.org/latest/pmd_userdocs_report_formats.html

Example of how to invoke PMD with the 'ideaj' format for a single file, specifying necessary properties like fileName, sourcePath, and classAndMethodName.

```bash
pmd check -d src/Foo.java -R rulesets/java/quickstart.xml -f ideaj -P fileName=src/Foo.java -P sourcePath=/home/pmd/src -P classAndMethodName=Foo
```

--------------------------------

### Jekyll Frontmatter Example

Source: https://docs.pmd-code.org/latest/pmd_devdocs_writing_documentation.html

Example of the YAML frontmatter section at the beginning of a Jekyll page, used for metadata like title and permalink.

```yaml
---
title: Writing Documentation
last_updated: January 2025 (7.10.0)
permalink: pmd_devdocs_writing_documentation.html
---

Some Text
```

--------------------------------

### Ant Verbose Output Example

Source: https://docs.pmd-code.org/latest/pmd_userdocs_tools_ant.html

Example of running the Ant PMD task with the verbose flag (-v) to see detailed output during execution.

```bash
[tom@hal bin]$ ant -v pmd
Apache Ant version 1.6.2 compiled on July 16 2004
Buildfile: build.xml
Detected Java version: 1.4 in: /usr/local/j2sdk1.4.2_03/jre
Detected OS: Linux
parsing buildfile build.xml with URI = file:/home/tom/data/pmd/pmd/bin/build.xml
Project base dir set to: /home/tom/data/pmd/pmd
Build sequence for target `pmd' is [pmd]
Complete build sequence is [pmd, copy, cppjavacc, cpd, delete,
 compile, clean, jar, dist, cpdjnlp, jjtree, javadoc, test, tomserver]

pmd:
      [pmd] Using the normal ClassLoader
      [pmd] Using these rulesets: rulesets/java/quickstart.xml
      [pmd] Using rule AvoidMessageDigestField
      [pmd] Using rule AvoidStringBufferField
      [pmd] Using rule AvoidUsingHardCodedIP
      [pmd] Using rule CheckResultSet
      [pmd] Using rule ConstantsInInterface
      ... 
      [pmd] Processing file /usr/local/java/src/java/lang/ref/Finalizer.java
      [pmd] Processing file /usr/local/java/src/java/lang/ref/FinalReference.java
      [pmd] Processing file /usr/local/java/src/java/lang/ref/PhantomReference.java
      [pmd] Processing file /usr/local/java/src/java/lang/ref/Reference.java
      [pmd] Processing file /usr/local/java/src/java/lang/ref/ReferenceQueue.java
      [pmd] Processing file /usr/local/java/src/java/lang/ref/SoftReference.java
      [pmd] Processing file /usr/local/java/src/java/lang/ref/WeakReference.java
      [pmd] 0 problems found

BUILD SUCCESSFUL
Total time: 2 seconds
[tom@hal bin]$
```

--------------------------------

### Build Module with Snapshot Dependencies

Source: https://docs.pmd-code.org/latest/pmd_devdocs_building_general.html

Build a specific module while including snapshot dependencies. Use '-am' to also build dependent modules, or '-Pcentral-portal-snapshots' to activate the snapshot repository.

```bash
./mvnw verify -pl pmd-apex -am
```

```bash
./mvnw verify -pl pmd-apex -Pcentral-portal-snapshots
```

--------------------------------

### Example of Inefficient Axis Usage

Source: https://docs.pmd-code.org/latest/pmd_rules_xsl_performance.html

This example demonstrates the use of the 'descendant::' axis within an XSLT variable selection, which is flagged by the AvoidAxisNavigation rule.

```xml
<xsl:variable name="var" select="//item/descendant::child"/>
```

--------------------------------

### PMD Rule Reference Example

Source: https://docs.pmd-code.org/latest/pmd_rules_java_errorprone.html

Shows how to reference PMD rules within a PMD configuration file. This is a common pattern for enabling specific checks.

```xml
<rule ref="category/java/errorprone.xml/JUnitStaticSuite" />
```

```xml
<rule ref="category/java/errorprone.xml/MethodWithSameNameAsEnclosingClass" />
```

```xml
<rule ref="category/java/errorprone.xml/MisplacedNullCheck" />
```

```xml
<rule ref="category/java/errorprone.xml/MissingSerialVersionUID" />
```

--------------------------------

### Dump Java AST to XML and Query with xmlstarlet

Source: https://docs.pmd-code.org/latest/pmd_userdocs_extending_ast_dump.html

Demonstrates dumping a Java AST to an XML file using PMD's ast-dump command and then querying specific nodes using xmlstarlet.

```bash
$ cat Foo.java
public class Foo {
  int a;
}

$ pmd ast-dump --format xml --language java --file Foo.java > Foo.xml
$ cat Foo.xml
<?xml version='1.0' encoding='UTF-8' ?>
<CompilationUnit Image='' PackageName=''>
    <ClassDeclaration Abstract='false' Annotation='false' Anonymous='false' BinaryName='Foo' CanonicalName='Foo' EffectiveVisibility='public' Enum='false' Final='false' Image='Foo' Interface='false' Local='false' Native='false' Nested='false' PackageName='' PackagePrivate='false' Private='false' Protected='false' Public='true' Record='false' RegularClass='true' RegularInterface='false' SimpleName='Foo' Static='false' Strictfp='false' Synchronized='false' SyntacticallyAbstract='false' SyntacticallyFinal='false' SyntacticallyPublic='true' SyntacticallyStatic='false' TopLevel='true' Transient='false' Visibility='public' Volatile='false'>
        <ModifierList Image='' />
        <ClassBody Empty='false' Image='' Size='1'>
            <FieldDeclaration Abstract='false' EffectiveVisibility='package' Final='false' Image='' Native='false' PackagePrivate='true' Private='false' Protected='false' Public='false' Static='false' Strictfp='false' Synchronized='false' SyntacticallyAbstract='false' SyntacticallyFinal='false' SyntacticallyPublic='false' SyntacticallyStatic='false' Transient='false' VariableName='a' Visibility='package' Volatile='false'>
                <ModifierList Image='' />
                <PrimitiveType ArrayDepth='0' ArrayType='false' ClassOrInterfaceType='false' Image='' Kind='int' PrimitiveType='true' TypeImage='int' />
                <VariableDeclarator Image='' Initializer='false' Name='a'>
                    <VariableId Abstract='false' ArrayType='false' EffectiveVisibility='package' EnumConstant='false' ExceptionBlockParameter='false' Field='true' Final='false' ForLoopVariable='false' ForeachVariable='false' FormalParameter='false' Image='a' LambdaParameter='false' LocalVariable='false' Name='a' Native='false' PackagePrivate='true' PatternBinding='false' Private='false' Protected='false' Public='false' RecordComponent='false' ResourceDeclaration='false' Static='false' Strictfp='false' Synchronized='false' SyntacticallyAbstract='false' SyntacticallyFinal='false' SyntacticallyPublic='false' SyntacticallyStatic='false' Transient='false' TypeInferred='false' VariableName='a' Visibility='package' Volatile='false' />
                </VariableDeclarator>
            </FieldDeclaration>
        </ClassBody>
    </ClassDeclaration>
</CompilationUnit>

$ xmlstarlet select -t -c "//VariableId[@VariableName='a']" Foo.xml
<VariableId Abstract="false" ArrayType="false" EffectiveVisibility="package" EnumConstant="false" ExceptionBlockParameter="false" Field="true" Final="false" ForLoopVariable="false" ForeachVariable="false" FormalParameter="false" Image="a" LambdaParameter="false" LocalVariable="false" Name="a" Native="false" PackagePrivate="true" PatternBinding="false" Private="false" Protected="false" Public="false" RecordComponent="false" ResourceDeclaration="false" Static="false" Strictfp="false" Synchronized="false" SyntacticallyAbstract="false" SyntacticallyFinal="false" SyntacticallyPublic="false" SyntacticallyStatic="false" Transient="false" TypeInferred="false" VariableName="a" Visibility="package" Volatile="false"/>
```

--------------------------------

### Get Explicit Modifiers with pmd-java:explicitModifiers

Source: https://docs.pmd-code.org/latest/pmd_userdocs_extending_writing_xpath_rules.html

Use `pmd-java:explicitModifiers` to get only the explicit modifiers of a node. The context node must be a `ModifierOwner`.

```xpath
//MethodDeclaration[pmd-java:explicitModifiers() = "public"]
```

--------------------------------

### Export and Verify GPG Public Key

Source: https://docs.pmd-code.org/latest/pmd_devdocs_github_actions_workflows.html

Export your GPG public key to a file and then use `gpg --show-keys` to verify its details. This is useful for confirming the key was exported correctly and for uploading to various key servers.

```bash
gpg --armor --export 2EFA55D0785C31F956F2F87EA0B5CA1A4E086838 > release-signing-key-2EFA55D0785C31F956F2F87EA0B5CA1A4E086838-public.asc
gpg --show-keys release-signing-key-2EFA55D0785C31F956F2F87EA0B5CA1A4E086838-public.asc
curl 'https://keys.openpgp.org/vks/v1/by-fingerprint/2EFA55D0785C31F956F2F87EA0B5CA1A4E086838' | gpg --show-keys
curl 'https://keyserver.ubuntu.com/pks/lookup?search=0x2EFA55D0785C31F956F2F87EA0B5CA1A4E086838&fingerprint=on&exact=on&options=mr&op=get' | gpg --show-keys
curl 'http://pgp.mit.edu/pks/lookup?op=get&search=0x2EFA55D0785C31F956F2F87EA0B5CA1A4E086838' | gpg --show-keys
```

--------------------------------

### PMD CLI Usage Help

Source: https://docs.pmd-code.org/latest/pmd_release_notes_pmd7.html

Displays the general usage help for the PMD Command Line Interface, including available commands and exit codes.

```bash
$ Usage: pmd [-hV] [COMMAND]
  -h, --help      Show this help message and exit.
  -V, --version   Print version information and exit.
Commands:
  check     The PMD standard source code analyzer
  cpd       Copy/Paste Detector - find duplicate code
  designer  The PMD visual rule designer
  cpd-gui   GUI for the Copy/Paste Detector
              Warning: May not support the full CPD feature set
  ast-dump  Experimental: dumps the AST of parsing source code
Exit Codes:
  0   Successful analysis, no violations found
  1   An unexpected error occurred during execution
  2   Usage error, please refer to the command help
  4   Successful analysis, at least 1 violation found

```

--------------------------------

### PLSQL Excessive Object Length Example

Source: https://docs.pmd-code.org/latest/pmd_rules_plsql_design.html

Example of a PL/SQL package body that might trigger the ExcessiveObjectLength rule. This rule is deprecated and replaced by NcssCount.

```plsql
CREATE OR REPLACE
PACKAGE BODY Foo AS
    PROCEDURE bar1 IS BEGIN
    -- 1000 lines of code
    END bar1;
    PROCEDURE bar2 IS BEGIN
    -- 1000 lines of code
    END bar2;
    PROCEDURE bar3 IS BEGIN
    -- 1000 lines of code
    END bar3;


    PROCEDURE barN IS BEGIN
    -- 1000 lines of code
    END barn;
END;
```

--------------------------------

### LogicInversion Rule Example

Source: https://docs.pmd-code.org/latest/pmd_rules_java_design.html

Demonstrates the LogicInversion rule, showing how to use opposite operators instead of negating expressions. Use '!=' instead of '!(==)' and '>=' instead of '!(<)'.

```java
public boolean bar(int a, int b) {

    if (!(a == b)) { // use !=
         return false;
     }

    if (!(a < b)) { // use >=
         return false;
    }

    return true;
}

```

--------------------------------

### XPath Rule Deprecation Warning Example

Source: https://docs.pmd-code.org/latest/pmd_userdocs_migrating_to_pmd7.html

Example of a deprecation warning for an XPath attribute in a custom rule. It suggests using '@Name' instead of '@Image' for 'VariableId'.

```text
WARNING: Use of deprecated attribute 'VariableId/@Image' by XPath rule 'VariableNaming' (in ruleset 'VariableNamingRule'), please use @Name instead
```

--------------------------------

### PLSQL NcssMethodCount Example

Source: https://docs.pmd-code.org/latest/pmd_rules_plsql_design.html

Example of a PLSQL function to be analyzed by the deprecated NcssMethodCount rule. This rule counts Non-Commenting Source Statements (NCSS) within a method.

```plsql
CREATE OR REPLACE PACKAGE BODY AS
 FUNCTION method RETURN INTEGER IS
 BEGIN
   RETURN 1;
 END;
END;

```

--------------------------------

### PLSQL Excessive Method Length Example

Source: https://docs.pmd-code.org/latest/pmd_rules_plsql_design.html

Example of a PL/SQL procedure that might trigger the ExcessiveMethodLength rule due to its length. This rule is deprecated and replaced by NcssCount.

```plsql
CREATE OR REPLACE
PROCEDURE doSomething BEGIN
    DBMS_OUTPUT.PUT_LINE("Hello world!");
    DBMS_OUTPUT.PUT_LINE("Hello world!");
        -- 98 copies omitted for brevity.
END;
```

--------------------------------

### Apex TooManyFields Rule Example (Problematic)

Source: https://docs.pmd-code.org/latest/pmd_rules_apex_design.html

This example shows a class with too many individual fields, which can make it unwieldy. Consider grouping related fields into objects.

```apex
public class Person {
    // too many separate fields
    Integer birthYear;
    Integer birthMonth;
    Integer birthDate;
    Double height;
    Double weight;
}


```

--------------------------------

### Control Statement Braces Examples

Source: https://docs.pmd-code.org/latest/pmd_rules_java_codestyle.html

Illustrates the difference between recommended and not-recommended brace usage in while loops. The preferred approach uses braces for clarity and maintainability.

```java
while (true)    // not recommended
  x++;

while (true) {  // preferred approach
  x++;
}
```

--------------------------------

### Correct JSP Encoding Example

Source: https://docs.pmd-code.org/latest/pmd_rules_jsp_errorprone.html

Examples of correctly declared content types with UTF-8 encoding in JSP pages using both meta tags and page directives.

```jsp
<%@ page contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
```

```html
<meta http-equiv="Content-Type"  content="text/html; charset=UTF-8" />
```

--------------------------------

### IntelliJ IDEA Report Format Example

Source: https://docs.pmd-code.org/latest/pmd_userdocs_report_formats.html

Formats output for IntelliJ IDEA's external tool integration. It displays violation descriptions and their location within the code, including class and method names.

```text
Logger calls should be surrounded by log level guards.
 at Foo(:124)
This for loop can be replaced by a foreach loop
 at Foo(:58)

```

--------------------------------

### Reference PMD InstantiationToGetClass Rule

Source: https://docs.pmd-code.org/latest/pmd_rules_java_errorprone.html

Demonstrates how to reference the `InstantiationToGetClass` rule in PMD using an XML configuration.

```xml
<rule ref="category/java/errorprone.xml/InstantiationToGetClass" />
```

--------------------------------

### Apex Excessive Class Length Example

Source: https://docs.pmd-code.org/latest/pmd_rules_apex_design.html

An example of an Apex class with multiple methods, each containing a large number of lines, which would be flagged by the ExcessiveClassLength rule.

```apex
public class Foo {
    public void bar1() {
        // 1000 lines of code
    }
    public void bar2() {
        // 1000 lines of code
    }
    public void bar3() {
        // 1000 lines of code
    }
    public void barN() {
        // 1000 lines of code
    }
}
```

--------------------------------

### UseUtilityClass Example

Source: https://docs.pmd-code.org/latest/pmd_rules_java_design.html

This example shows a class with only static methods. The UseUtilityClass rule suggests making such classes utility classes by adding a private constructor to prevent instantiation.

```java
public class MaybeAUtility {
  public static void foo() {}
  public static void bar() {}
}
```

--------------------------------

### Code Sample with Syntax Highlighting

Source: https://docs.pmd-code.org/latest/pmd_devdocs_writing_documentation.html

Embed code samples using fenced code blocks with the language specified for syntax highlighting. This example uses Java.

```java
public class Foo {
    public void bar() { System.out.println("x"); }
}
```

--------------------------------

### PLSQL NcssObjectCount Example

Source: https://docs.pmd-code.org/latest/pmd_rules_plsql_design.html

Example of a PLSQL package to be analyzed by the deprecated NcssObjectCount rule. This rule counts Non-Commenting Source Statements (NCSS) within an Oracle object.

```plsql
CREATE OR REPLACE PACKAGE pkg_ IS
 PROCEDURE Foo IS
 BEGIN
 --this class only has 6 NCSS lines
     super();
     super();
 END Foo;
END;

```

--------------------------------

### Apex TooManyFields Rule Example (Improved)

Source: https://docs.pmd-code.org/latest/pmd_rules_apex_design.html

This improved example demonstrates how to manage fields more effectively by grouping related data into dedicated objects, making the class more manageable.

```apex
public class Person {
    // this is more manageable
    Date birthDate;
    BodyMeasurements measurements;
}


```

--------------------------------

### Example of Lambda to Method Reference Conversion

Source: https://docs.pmd-code.org/latest/pmd_rules_java_codestyle.html

Demonstrates how lambdas like `s -> s.length()` and `(x, y) -> Integer.sum(x, y)` can be converted to method references `String::length` and `Integer::sum` respectively.

```java
import java.util.stream.Stream;

            public class LambdaCanBeMethodReference {
                static {
                    Stream.of("abc", "d")
                            .mapToInt(s -> s.length()) // could be String::length
                            .reduce((x, y) -> Integer.sum(x, y)) // could be Integer::sum
                            .getAsInt();
                }
            }
```

--------------------------------

### Configure PMD for TextPad (Directory Analysis)

Source: https://docs.pmd-code.org/latest/pmd_userdocs_tools_ide_plugins.html

This configuration sets up PMD to analyze a directory of Java files within TextPad. Ensure your PMD and JDK paths are correctly specified. The parameters define the PMD execution, output rendering, and ruleset to use.

```text
-classpath D:\java\pmd-bin-\lib\pmd-.jar;D:\java\pmd-bin-\lib\asm-3.2.jar;D:\java\pmd-bin-\lib\jaxen-1.1.1.jar net.sourceforge.pmd.PMD -d $FileDir -f net.sourceforge.pmd.renderers.TextPadRenderer -R E:\directory\my_pmd_ruleset.xml -debug
```

--------------------------------

### Java Comment Required Rule Example

Source: https://docs.pmd-code.org/latest/pmd_rules_java_documentation.html

This rule checks for the presence or absence of Javadoc comments on various code elements. The example shows a valid Javadoc structure.

```java
/**
*
*
* @author Jon Doe
*/
```

--------------------------------

### IntelliJ IDEA CLI Command for Directory

Source: https://docs.pmd-code.org/latest/pmd_userdocs_report_formats.html

Example of how to invoke PMD with the 'ideaj' format for a directory, omitting the fileName property and using '.method' for classAndMethodName when processing directories.

```bash
pmd check -d src -R rulesets/java/quickstart.xml -f ideaj -P sourcePath=/home/pmd/src -P classAndMethodName=.method
```

--------------------------------

### Java Varargs Array Creation Example

Source: https://docs.pmd-code.org/latest/pmd_rules_java_bestpractices.html

This example shows an unnecessary explicit array creation for a varargs parameter in `Arrays.asList`. The commented-out line indicates the preferred, more concise syntax.

```java
import java.util.Arrays;

class C {
    static {
        Arrays.asList(new String[]{"foo", "bar",});
        // should be
        Arrays.asList("foo", "bar");
    }
}

```

--------------------------------

### Reference NoPackage Rule

Source: https://docs.pmd-code.org/latest/pmd_rules_java_codestyle.html

Shows how to reference the NoPackage rule in PMD configuration.

```xml
<rule ref="category/java/codestyle.xml/NoPackage" />
```

--------------------------------

### Java Cyclomatic Complexity Example

Source: https://docs.pmd-code.org/latest/pmd_rules_java_design.html

Illustrates a Java method with high cyclomatic complexity, highlighting decision points that contribute to the complexity score. This example is reported by the CyclomaticComplexity rule.

```java
class Foo {
  void baseCyclo() {                // Cyclo = 1
    highCyclo();
  }

  void highCyclo() {                // Cyclo = 10: reported!
    int x = 0, y = 2;
    boolean a = false, b = true;

    if (a && (y == 1 ? b : true)) { // +3
      if (y == x) {                 // +1
        while (true) {              // +1
          if (x++ < 20) {           // +1
            break;                  // +1
          }
        }
      } else if (y == t && !d) {    // +2
        x = a ? y : x;              // +1
      } else {
        x = 2;
      }
    }
  }
}

```

--------------------------------

### PMD CPD Command Example

Source: https://docs.pmd-code.org/latest/pmd_release_notes_pmd7.html

Demonstrates how to use the PMD Copy/Paste Detector (CPD) command with a specific option to find duplicate code.

```bash
pmd cpd --minimum-tokens 100 src/main/java

```

--------------------------------

### Boolean Get Method Naming Convention

Source: https://docs.pmd-code.org/latest/pmd_rules_java_codestyle.html

Ensures methods returning boolean or Boolean results are named as predicates (e.g., 'isReady()', 'hasValues()') instead of using the 'get' prefix.

```java
public boolean getFoo();            // bad
public Boolean getFoo();            // bad
public boolean isFoo();             // ok
public Boolean isFoo();             // ok
public boolean getFoo(boolean bar); // ok, unless checkParameterizedMethods=true
```

--------------------------------

### PMD AST Dump Help Command

Source: https://docs.pmd-code.org/latest/pmd_userdocs_extending_ast_dump.html

Displays the help message for the 'pmd ast-dump' command, outlining available options and their descriptions. Use this to understand the full range of customization for AST dumping.

```bash
$ pmd ast-dump --help
Usage: pmd ast-dump [-Dhi] [-e=<encoding>] [-f=<format>] [--file=<file>]
                    [-l=<language>] [-P=<String=String>]...
Dumps the AST of parsing source code
  -D, -v, --debug, --verbose
                          Debug mode.
  -e, --encoding=<encoding>
                          Specifies the character set encoding of the source
                            code files
  -f, --format=<format>   The output format.
                          Valid values: xml, text
      --file=<file>       The file to parse and dump.
  -h, --help              Show this help message and exit.
  -i, --read-stdin        Read source from standard input.
  -l, --language=<language>
                          The source code language.
                          Valid values: apex, ecmascript, html, java, jsp, 
                            kotlin, modelica, plsql, pom, scala, swift, vf, vm, 
                            wsdl, xml, xsl
  -P=<String=String>      Key-value pair defining a property for the report
                            format.
                          Supported values for each report format:
                          xml:
                            singleQuoteAttributes - Use single quotes to
                            delimit attribute values
                              Default: true
                            lineSeparator - Line separator to use. The default
                            is platform-specific. The values 'CR', 'CRLF',
                            'LF', '\r', '\r\n' and '\n' can be used to
                            represent a carriage return, line feed and their
                            combination more easily.
                              Default: 
                            renderProlog - True to output a prolog
                              Default: true
                            renderCommonAttributes - True to render attributes
                            like BeginLine, EndLine, etc.
                              Default: false
                          text:
                            onlyAsciiChars - Use only ASCII characters in the
                            structure
                              Default: false
                            maxLevel - Max level on which to recurse. Negative
                            means unbounded
                              Default: -1

```

--------------------------------

### Get Logger Instance with SLF4J

Source: https://docs.pmd-code.org/latest/pmd_devdocs_logging.html

This is the standard way to get a logger instance in Java using SLF4J. It's typically stored in a static final field named LOG.

```java
private static final Logger LOG = LoggerFactory.getLogger(MyClass.class);
```

--------------------------------

### Java Comment Size Rule Example

Source: https://docs.pmd-code.org/latest/pmd_rules_java_documentation.html

This rule enforces limits on the number of lines and line length for non-header comments. The example demonstrates a comment exceeding the default line limit.

```java
/**
*
*   too many lines!
*
*
*
*
*
*
*
*
*
*
*/
```

--------------------------------

### Clean and Update Code

Source: https://docs.pmd-code.org/latest/pmd_projectdocs_committers_releasing.html

Before starting the release preparations, ensure your local code is up-to-date and clean. This involves cleaning the project with Maven wrapper and pulling the latest changes from the repository.

```bash
$ ./mvnw clean
$ git pull
$ git status

```

--------------------------------

### Use Rule Reference for DoNotTerminateVM

Source: https://docs.pmd-code.org/latest/pmd_rules_java_errorprone.html

Shows how to reference the DoNotTerminateVM rule in PMD configuration.

```xml
<rule ref="category/java/errorprone.xml/DoNotTerminateVM" />

```

--------------------------------

### Custom Rule Test Setup in Java

Source: https://docs.pmd-code.org/latest/pmd_userdocs_extending_testing.html

Extend SimpleAggregatorTst and override setUp to register your custom rules and their corresponding rulesets. This is necessary when developing rules outside the PMD source base.

```java
package com.example.pmd.rules;

import net.sourceforge.pmd.test.SimpleAggregatorTst;

class CustomRuleTest extends SimpleAggregatorTst {
    @Override
    protected void setUp() {
        addRule("com/example/pmd/ruleset.xml", "CustomRule");
    }
}
```

--------------------------------

### Generate Release Notes Script

Source: https://docs.pmd-code.org/latest/pmd_projectdocs_committers_releasing.html

Execute the release-notes-generate.sh script with the last and release versions as parameters to update the release notes. Ensure GITHUB_TOKEN is set if rate limiting occurs.

```bash
.ci/tool/release-notes-generate.sh 7.14.0 7.15.0

```

--------------------------------

### Example of Confusing Ternary Usage

Source: https://docs.pmd-code.org/latest/pmd_rules_java_codestyle.html

Demonstrates a common pattern that the ConfusingTernary rule aims to rephrase for better readability. This specific example shows a ternary operator where the condition `x != y` could be inverted for clarity.

```java
boolean bar(int x, int y) {
    return (x != y) ? diff : same;
}
```