# Design

Rules that help you discover design issues.
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## AvoidDeeplyNestedIfStmts

Since: PMD 5.5.0

Priority: Medium (3)

Avoid creating deeply nested if-then statements since they are harder to read and error-prone to maintain.

This rule is defined by the following Java class: net.sourceforge.pmd.lang.apex.rule.design.AvoidDeeplyNestedIfStmtsRule

Example(s):

    public class Foo {
        public void bar(Integer x, Integer y, Integer z) {
            if (x>y) {
                if (y>z) {
                    if (z==x) {
                        // !! too deep
                    }
                }
            }
        }
    }

This rule has the following properties:

Name | Default Value | Description | Multivalued
--- | --- | --- | ---
cc_categories | Complexity | Deprecated Code Climate Categories | yes. Delimiter is ‘|’.
cc_remediation_points_multiplier | 200 | Deprecated Code Climate Remediation Points multiplier | no
cc_block_highlighting | false | Deprecated Code Climate Block Highlighting | no
problemDepth | 3 | The if statement depth reporting threshold | no

Use this rule with the default properties by just referencing it:

    <rule ref="category/apex/design.xml/AvoidDeeplyNestedIfStmts" />

Use this rule and customize it:

    <rule ref="category/apex/design.xml/AvoidDeeplyNestedIfStmts">
        <properties>
            <property name="problemDepth" value="3" />
        </properties>
    </rule>

## CognitiveComplexity

Since: PMD 6.22.0

Priority: Medium (3)

Methods that are highly complex are difficult to read and more costly to maintain. If you include too much decisional logic within a single method, you make its behavior hard to understand and more difficult to modify.

Cognitive complexity is a measure of how difficult it is for humans to read and understand a method. Code that contains a break in the control flow is more complex, whereas the use of language shorthands doesn’t increase the level of complexity. Nested control flows can make a method more difficult to understand, with each additional nesting of the control flow leading to an increase in cognitive complexity.

Information about Cognitive complexity can be found in the original paper here: https://www.sonarsource.com/docs/CognitiveComplexity.pdf

By default, this rule reports methods with a complexity of 15 or more. Reported methods should be broken down into less complex components.

This rule is defined by the following Java class: net.sourceforge.pmd.lang.apex.rule.design.CognitiveComplexityRule

Example(s):

    public class Foo {
        // Has a cognitive complexity of 0
        public void createAccount() {
            Account account = new Account(Name = 'PMD');
            insert account;
        }

        // Has a cognitive complexity of 1
        public Boolean setPhoneNumberIfNotExisting(Account a, String phone) {
            if (a.Phone == null) {                          // +1
                a.Phone = phone;
                update a;
                return true;
            }

            return false;
        }

        // Has a cognitive complexity of 4
        public void updateContacts(List<Contact> contacts) {
            List<Contact> contactsToUpdate = new List<Contact>();

            for (Contact contact : contacts) {                           // +1
                if (contact.Department == 'Finance') {                   // +2 (nesting = 1)
                    contact.Title = 'Finance Specialist';
                    contactsToUpdate.add(contact);
                } else if (contact.Department == 'Sales') {              // +1
                    contact.Title = 'Sales Specialist';
                    contactsToUpdate.add(contact);
                }
            }

            update contactsToUpdate;
        }
    }

This rule has the following properties:

Name | Default Value | Description | Multivalued
--- | --- | --- | ---
cc_categories | Style | Deprecated Code Climate Categories | yes. Delimiter is ‘|’.
cc_remediation_points_multiplier | 1 | Deprecated Code Climate Remediation Points multiplier | no
cc_block_highlighting | false | Deprecated Code Climate Block Highlighting | no
classReportLevel | 50 | Total class cognitive complexity reporting threshold | no
methodReportLevel | 15 | Cognitive complexity reporting threshold | no

Use this rule with the default properties by just referencing it:

    <rule ref="category/apex/design.xml/CognitiveComplexity" />

Use this rule and customize it:

    <rule ref="category/apex/design.xml/CognitiveComplexity">
        <properties>
            <property name="classReportLevel" value="50" />
            <property name="methodReportLevel" value="15" />
        </properties>
    </rule>

## CyclomaticComplexity

Since: PMD 6.0.0

Priority: Medium (3)

The complexity of methods directly affects maintenance costs and readability. Concentrating too much decisional logic in a single method makes its behaviour hard to read and change.

Cyclomatic complexity assesses the complexity of a method by counting the number of decision points in a method, plus one for the method entry. Decision points are places where the control flow jumps to another place in the program. As such, they include all control flow statements, such as ‘if’, ‘while’, ‘for’, and ‘case’.

Generally, numbers ranging from 1-4 denote low complexity, 5-7 denote moderate complexity, 8-10 denote high complexity, and 11+ is very high complexity. By default, this rule reports methods with a complexity >= 10. Additionally, classes with many methods of moderate complexity get reported as well once the total of their methods’ complexities reaches 40, even if none of the methods was directly reported.

Reported methods should be broken down into several smaller methods. Reported classes should probably be broken down into subcomponents.

This rule is defined by the following Java class: net.sourceforge.pmd.lang.apex.rule.design.CyclomaticComplexityRule

Example(s):

    public class Complicated {
      public void example() { // This method has a cyclomatic complexity of 12
        int x = 0, y = 1, z = 2, t = 2;
        boolean a = false, b = true, c = false, d = true;
        if (a && b || b && d) {
          if (y == z) {
            x = 2;
          } else if (y == t && !d) {
            x = 2;
          } else {
            x = 2;
          }
        } else if (c && d) {
          while (z < y) {
            x = 2;
          }
        } else {
          for (int n = 0; n < t; n++) {
            x = 2;
          }
        }
      }
    }

This rule has the following properties:

Name | Default Value | Description | Multivalued
--- | --- | --- | ---
cc_categories | Style | Deprecated Code Climate Categories | yes. Delimiter is ‘|’.
cc_remediation_points_multiplier | 1 | Deprecated Code Climate Remediation Points multiplier | no
cc_block_highlighting | false | Deprecated Code Climate Block Highlighting | no
classReportLevel | 40 | Total class complexity reporting threshold | no
methodReportLevel | 10 | Cyclomatic complexity reporting threshold | no

Use this rule with the default properties by just referencing it:

    <rule ref="category/apex/design.xml/CyclomaticComplexity" />

Use this rule and customize it:

    <rule ref="category/apex/design.xml/CyclomaticComplexity">
        <properties>
            <property name="classReportLevel" value="40" />
            <property name="methodReportLevel" value="10" />
        </properties>
    </rule>

## ExcessiveClassLength

Since: PMD 5.5.0

Priority: Medium (3)

Excessive class file lengths are usually indications that the class may be burdened with excessive responsibilities that could be provided by external classes or functions. In breaking these methods apart the code becomes more managable and ripe for reuse.

This rule is defined by the following Java class: net.sourceforge.pmd.lang.apex.rule.design.ExcessiveClassLengthRule

Example(s):

    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
        }
    }

This rule has the following properties:

Name | Default Value | Description | Multivalued
--- | --- | --- | ---
topscore |  | Deprecated Top score value | no
minimum | 1000.0 | Minimum reporting threshold | no
cc_categories | Complexity | Deprecated Code Climate Categories | yes. Delimiter is ‘|’.
cc_remediation_points_multiplier | 150 | Deprecated Code Climate Remediation Points multiplier | no
cc_block_highlighting | false | Deprecated Code Climate Block Highlighting | no
sigma |  | Deprecated Sigma value | no

Use this rule with the default properties by just referencing it:

    <rule ref="category/apex/design.xml/ExcessiveClassLength" />

Use this rule and customize it:

    <rule ref="category/apex/design.xml/ExcessiveClassLength">
        <properties>
            <property name="minimum" value="1000.0" />
        </properties>
    </rule>

## ExcessiveParameterList

Since: PMD 5.5.0

Priority: Medium (3)

Methods with numerous parameters are a challenge to maintain, especially if most of them share the same datatype. These situations usually denote the need for new objects to wrap the numerous parameters.

This rule is defined by the following Java class: net.sourceforge.pmd.lang.apex.rule.design.ExcessiveParameterListRule

Example(s):

    // too many arguments liable to be mixed up
    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) {
        // ...
    }

This rule has the following properties:

Name | Default Value | Description | Multivalued
--- | --- | --- | ---
topscore |  | Deprecated Top score value | no
minimum | 4.0 | Minimum reporting threshold | no
cc_categories | Complexity | Deprecated Code Climate Categories | yes. Delimiter is ‘|’.
cc_remediation_points_multiplier | 50 | Deprecated Code Climate Remediation Points multiplier | no
cc_block_highlighting | false | Deprecated Code Climate Block Highlighting | no
sigma |  | Deprecated Sigma value | no

Use this rule with the default properties by just referencing it:

    <rule ref="category/apex/design.xml/ExcessiveParameterList" />

Use this rule and customize it:

    <rule ref="category/apex/design.xml/ExcessiveParameterList">
        <properties>
            <property name="minimum" value="4.0" />
        </properties>
    </rule>

## ExcessivePublicCount

Since: PMD 5.5.0

Priority: Medium (3)

Classes with large numbers of public methods and attributes require disproportionate testing efforts since combinational side effects grow rapidly and increase risk. Refactoring these classes into smaller ones not only increases testability and reliability but also allows new variations to be developed easily.

This rule is defined by the following Java class: net.sourceforge.pmd.lang.apex.rule.design.ExcessivePublicCountRule

Example(s):

    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 ...]
    }

This rule has the following properties:

Name | Default Value | Description | Multivalued
--- | --- | --- | ---
topscore |  | Deprecated Top score value | no
minimum | 20.0 | Minimum reporting threshold | no
cc_categories | Complexity | Deprecated Code Climate Categories | yes. Delimiter is ‘|’.
cc_remediation_points_multiplier | 150 | Deprecated Code Climate Remediation Points multiplier | no
cc_block_highlighting | false | Deprecated Code Climate Block Highlighting | no
sigma |  | Deprecated Sigma value | no

Use this rule with the default properties by just referencing it:

    <rule ref="category/apex/design.xml/ExcessivePublicCount" />

Use this rule and customize it:

    <rule ref="category/apex/design.xml/ExcessivePublicCount">
        <properties>
            <property name="minimum" value="20.0" />
        </properties>
    </rule>

## NcssConstructorCount

Since: PMD 5.5.0

Priority: Medium (3)

This rule uses the NCSS (Non-Commenting Source Statements) algorithm to determine the number of lines of code for a given constructor. NCSS ignores comments, and counts actual statements. Using this algorithm, lines of code that are split are counted as one.

This rule is defined by the following Java class: net.sourceforge.pmd.lang.apex.rule.design.NcssConstructorCountRule

Example(s):

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

            super.foo();
    }
    }

This rule has the following properties:

Name | Default Value | Description | Multivalued
--- | --- | --- | ---
topscore |  | Deprecated Top score value | no
minimum | 20.0 | Minimum reporting threshold | no
cc_categories | Complexity | Deprecated Code Climate Categories | yes. Delimiter is ‘|’.
cc_remediation_points_multiplier | 50 | Deprecated Code Climate Remediation Points multiplier | no
cc_block_highlighting | false | Deprecated Code Climate Block Highlighting | no
sigma |  | Deprecated Sigma value | no

Use this rule with the default properties by just referencing it:

    <rule ref="category/apex/design.xml/NcssConstructorCount" />

Use this rule and customize it:

    <rule ref="category/apex/design.xml/NcssConstructorCount">
        <properties>
            <property name="minimum" value="20.0" />
        </properties>
    </rule>

## NcssMethodCount

Since: PMD 5.5.0

Priority: Medium (3)

This rule uses the NCSS (Non-Commenting Source Statements) algorithm to determine the number of lines of code for a given method. NCSS ignores comments, and counts actual statements. Using this algorithm, lines of code that are split are counted as one.

This rule is defined by the following Java class: net.sourceforge.pmd.lang.apex.rule.design.NcssMethodCountRule

Example(s):

    public class Foo extends Bar {
        //this method only has 1 NCSS lines
        public Integer method() {
            super.method();

            return 1;
        }
    }

This rule has the following properties:

Name | Default Value | Description | Multivalued
--- | --- | --- | ---
topscore |  | Deprecated Top score value | no
minimum | 40.0 | Minimum reporting threshold | no
cc_categories | Complexity | Deprecated Code Climate Categories | yes. Delimiter is ‘|’.
cc_remediation_points_multiplier | 50 | Deprecated Code Climate Remediation Points multiplier | no
cc_block_highlighting | false | Deprecated Code Climate Block Highlighting | no
sigma |  | Deprecated Sigma value | no

Use this rule with the default properties by just referencing it:

    <rule ref="category/apex/design.xml/NcssMethodCount" />

Use this rule and customize it:

    <rule ref="category/apex/design.xml/NcssMethodCount">
        <properties>
            <property name="minimum" value="40.0" />
        </properties>
    </rule>

## NcssTypeCount

Since: PMD 5.5.0

Priority: Medium (3)

This rule uses the NCSS (Non-Commenting Source Statements) algorithm to determine the number of lines of code for a given type. NCSS ignores comments, and counts actual statements. Using this algorithm, lines of code that are split are counted as one.

This rule is defined by the following Java class: net.sourceforge.pmd.lang.apex.rule.design.NcssTypeCountRule

Example(s):

    //this class only has 6 NCSS lines
    public class Foo extends Bar {
        public Foo() {
            super();

            super.foo();
        }
    }

This rule has the following properties:

Name | Default Value | Description | Multivalued
--- | --- | --- | ---
topscore |  | Deprecated Top score value | no
minimum | 500.0 | Minimum reporting threshold | no
cc_categories | Complexity | Deprecated Code Climate Categories | yes. Delimiter is ‘|’.
cc_remediation_points_multiplier | 250 | Deprecated Code Climate Remediation Points multiplier | no
cc_block_highlighting | false | Deprecated Code Climate Block Highlighting | no
sigma |  | Deprecated Sigma value | no

Use this rule with the default properties by just referencing it:

    <rule ref="category/apex/design.xml/NcssTypeCount" />

Use this rule and customize it:

    <rule ref="category/apex/design.xml/NcssTypeCount">
        <properties>
            <property name="minimum" value="500.0" />
        </properties>
    </rule>

## StdCyclomaticComplexity

Since: PMD 5.5.0

Priority: Medium (3)

Complexity directly affects maintenance costs is determined by the number of decision points in a method plus one for the method entry. The decision points include ‘if’, ‘while’, ‘for’, and ‘case labels’ calls. Generally, numbers ranging from 1-4 denote low complexity, 5-7 denote moderate complexity, 8-10 denote high complexity, and 11+ is very high complexity.

This rule is defined by the following Java class: net.sourceforge.pmd.lang.apex.rule.design.StdCyclomaticComplexityRule

Example(s):

    // 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;
            }
        }
    }

This rule has the following properties:

Name | Default Value | Description | Multivalued
--- | --- | --- | ---
cc_categories | Complexity | Deprecated Code Climate Categories | yes. Delimiter is ‘|’.
cc_remediation_points_multiplier | 250 | Deprecated Code Climate Remediation Points multiplier | no
cc_block_highlighting | false | Deprecated Code Climate Block Highlighting | no
reportLevel | 10 | Cyclomatic Complexity reporting threshold | no
showClassesComplexity | true | Add class average violations to the report | no
showMethodsComplexity | true | Add method average violations to the report | no

Use this rule with the default properties by just referencing it:

    <rule ref="category/apex/design.xml/StdCyclomaticComplexity" />

Use this rule and customize it:

    <rule ref="category/apex/design.xml/StdCyclomaticComplexity">
        <properties>
            <property name="reportLevel" value="10" />
            <property name="showClassesComplexity" value="true" />
            <property name="showMethodsComplexity" value="true" />
        </properties>
    </rule>

## TooManyFields

Since: PMD 5.5.0

Priority: Medium (3)

Classes that have too many fields can become unwieldy and could be redesigned to have fewer fields, possibly through grouping related fields in new objects. For example, a class with individual city/state/zip fields could park them within a single Address field.

This rule is defined by the following Java class: net.sourceforge.pmd.lang.apex.rule.design.TooManyFieldsRule

Example(s):

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

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

This rule has the following properties:

Name | Default Value | Description | Multivalued
--- | --- | --- | ---
cc_categories | Complexity | Deprecated Code Climate Categories | yes. Delimiter is ‘|’.
cc_remediation_points_multiplier | 200 | Deprecated Code Climate Remediation Points multiplier | no
cc_block_highlighting | false | Deprecated Code Climate Block Highlighting | no
maxfields | 15 | Max allowable fields | no

Use this rule with the default properties by just referencing it:

    <rule ref="category/apex/design.xml/TooManyFields" />

Use this rule and customize it:

    <rule ref="category/apex/design.xml/TooManyFields">
        <properties>
            <property name="maxfields" value="15" />
        </properties>
    </rule>