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Arrays do not override the Object.equals() method; rather, the implementation of the equals() method compares array references rather than their contents. Programs must use the two-argument Arrays.equals() method to compare the contents of two arrays. Programs must use the reference equality operators, == and !=, when intentionally testing reference equality. Programs also must not use the array equals() method because it can lead to unexpected results.

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public void arrayEqualsExample() {

  int[] arr1 = new int[20]; // initialized to 0
  int[] arr2 = new int[20]; // initialized to 0
  arr1.equals(arr2); // false

}

Compliant Solution

This compliant solution compares the two arrays using the two-argument Arrays.equals() method.

public void arrayEqualsExample() {

  int[] arr1 = new int[20]; // initialized to 0
  int[] arr2 = new int[20]; // initialized to 0
  Arrays.equals(arr1, arr2); // true

}

Risk Assessment

Using the equals() method or relational operators with the intention of comparing array contents produces incorrect results, which can lead to vulnerabilities.

Automated Detection

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Static detection of attempts to use array_objectcalls to Array.equals(...) appears to be is straightforward.

Related Guidelines

Bibliography

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