<!DOCTYPE qhelp PUBLIC

"-//Semmle//qhelp//EN"

"qhelp.dtd">

<qhelp>

<overview>

<p>

Enum constants that are never used at runtime are redundant and should be removed.

</p>

<include src="DeadCodeSummary.inc.qhelp"/>

<p>

An enum constant is considered dead if at runtime it is never used, or only used in comparisons. Any

enum constant which is not dead is considered to be "live".

</p>

<p>

An enum constant that is only used in a comparison is considered dead because the comparison will

always produce the same result. This is because no variable holds the value of the enum constant,

so the comparison of any variable against the constant will always return the same result.

</p>

<include src="DeadCodeDetails.inc.qhelp"/>

</overview>

<recommendation>

<p>

Before making any changes, confirm that the enum constant is not required by verifying that the

enum constant is never used. This confirmation is necessary because there may be project-specific

frameworks or techniques which can introduce hidden dependencies. If this project is for a library,

then consider whether the enum constant is part of the external API, and may be used in external

projects that are not included in the snapshot.

</p>

<p>

After confirming that the enum constant is not required, remove the enum constant. You will also

need to remove any references to this enum constant, which may, in turn, require removing other dead

code.

</p>

<include src="DeadCodeExtraEntryPoints.inc.qhelp"/>

</recommendation>

<example>

<p>

In the following example, we have an enum class called <code>Result</code>, intended to report the

result of some operation:

</p>

<sample src="DeadEnumConstant.java" />

<p>

The method <code>runOperation</code> performs some operation, and returns a <code>Result</code>

depending on whether the operation succeeded. However, it only returns either <code>SUCCESS</code>

or <code>FAILURE</code>, and never <code>ERROR</code>. The <code>main</code> method calls

<code>runOperation</code>, and checks whether the returned result is the <code>ERROR</code>.

However, this check will always return the same result - <code>false</code>. This is because the

<code>operationResult</code> can never hold <code>ERROR</code>, because <code>ERROR</code> is never

stored or returned anywhere in the program. Therefore, <code>ERROR</code> is dead and can be removed,

along with the comparison check, and the <code>exit(1);</code>.

</p>

</example>

<include src="DeadCodeReferences.inc.qhelp" />

</qhelp>