Page History

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Noncompliant Code Example

This noncompliant code is attempting attempts to delete all the null names from the list in an assertion. However, the boolean expression is not evaluated when assertions are disabled.

private ArrayList<String> names;

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

Compliant Solution

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

private ArrayList<String> names;

void process(int index) {
  boolean nullsRemoved = names.remove(null);
  assert nullsRemoved; // noNo side effect 
  // ... 
}

Risk Assessment

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Automated Detection

Automated detection of assertion operands that contain locally visible side effects is straightforward. Some analyses could require programmer assistance to determine which method invocations lack side effects.

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The assert statement is supported on the Dalvik VM but is ignored under the default configuration. Assertions may be enabled by setting the system property "debug.assert" via: adb shell setprop debug.assert 1 or by sending the command line argument "--enable-assert" to the Dalvik VM.

Bibliography

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