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This noncompliant code example demonstrates an action being carried out in an assertion. The idea is to delete all the null names from the list; however, the boolean expression is unexpectedly not evaluated when assertions are disabled.

private ArrayList<String> names;

void process(int index) {
  assert names.remove(null); // side-effect 
  // ...
}

Compliant Solution

Avoid the possibility of side effects in assertions. This can be achieved by decoupling the boolean expression from the assertion.

private ArrayList<String> names;

void process(int index) {
  boolean nullsRemoved = names.remove(null);
  assert nullsRemoved; // no side-effect 
  // ... 
}

Risk Assessment

Side effects in assertions results in program behavior that depends on whether assertions are enabled or disabled.

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