The definitions of two constant expressions should be related when, and only when, the values they express are also related.
Noncompliant Code Example
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:
public static final int IN_STR_LEN = 18; public static final int OUT_STR_LEN = 12;
Compliant Solution
In this compliant solution, the relationship between the two values is represented in the definitions:
public static final int IN_STR_LEN = 18; public static final int OUT_STR_LEN = IN_STR_LEN + 2;
Noncompliant Code Example
In this noncompliant code example, there appears to be an underlying relationship between the two constants where none exists.
public static final int ADULT_AGE = 18; public static final int ALCOHOL_AGE = ADULT_AGE + 3;
A programmer performing routine maintenance may modify the definition for ADULT_AGE but fail to recognize the resulting change in the definition for ALCOHOL_AGE.
Compliant Solution
In this compliant solution, the definitions reflect the independence of the two constants.
public static final int ADULT_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 |
Automated Detection
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
[[JLS 2005]] §4.12.4, "final Variables"
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