The definitions of two constant expressions should be related when, and only when, related exactly when the values they express are also related.
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In this noncompliant code example, OUT_STR_LEN must always be exactly two greater than IN_STR_LEN. These definitions fail to reflect this requirement:
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public static final int IN_STR_LEN = 18; public static final int OUT_STR_LEN = 1220; |
Compliant Solution
In this compliant solution, the relationship between the two values is represented in the definitions:
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public static final int IN_STR_LEN = 18;
public static final int OUT_STR_LEN = IN_STR_LEN + 2;
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In this noncompliant code example, there appears to be an underlying relationship between the two constants where none exists.:
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public static final int ADULTVOTING_AGE = 18; public static final int ALCOHOL_AGE = ADULTVOTING_AGE + 3; |
A programmer performing routine maintenance may modify the definition for ADULTVOTING_AGE but fail to recognize the resulting change in the definition for ALCOHOL_AGE.
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In this compliant solution, the definitions reflect the independence of the two constants.:
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public static final int ADULTVOTING_AGE = 18; public static final int ALCOHOL_AGE = 21; |
Risk Assessment
Failure to properly encode relationships in constant declarations can lead to unexpected values and can complicate maintenance.
Guideline | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
DCL03-J | low | unlikely | high | P1 | L3 |
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Automated detection is not currently feasible.
Related Guidelines
C Secure Coding Standard: "DCL08-C. Properly encode relationships in constant definitions"
C++ Secure Coding Standard: "DCL08-CPP. Properly encode relationships in constant definitions"
Bibliography
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| [JLS |
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}} Variables"|http://java.sun.com/docs/books/jls/third_edition/html/typesValues.html#4.12.4]DCL53-J. Use meaningful symbolic constants to represent literal values in program logic 01. Declarations and Initialization (DCL) DCL04-J. Do not apply public final to constants whose value might change