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This statement can be misleading because it is inapplicable to instances that use values of static final fields that are initialized at a later stage. Declaring a field to be static final is insufficient to guarantee that it is fully initialized before being read.

Programs in general should — and security sensitive programs must — eliminate all class initialization cycles.

Noncompliant Code Example (Intra-Class Cycle)

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Such initialization cycles become insidious when many fields are involved; ensure that the control flow lacks such cycles.

Although this compliant solution prevents the initialization cycle, it depends on declaration order and is consequently fragile; later maintainers of the software may be unaware that the declaration order must be maintained to preserve correctness. Consequently, such dependencies must be clearly documented in the code.

Noncompliant Code Example (Inter-Class Cycle)

This noncompliant code example declares two classes with static variables whose values depend on each other. The cycle is obvious when the classes are seen together (like they are as here), but this can easily be missed when viewing the classes are viewed separately.

class A {
    public static final int a = B.b + 1;
    // ...
}

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Automated Detection

TODO

Related Guidelines

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