EXP02-J. Do not use the equals method to compare the contents of arrays

Arrays do not override class Object's equals() method. Consequently, the default implementation of the equals() method simply compares the array references instead of the contents of the arrays. If only the references need to be compared, it is better to use relational operators, such as == and !=. Vulnerabilities can result, for instance, when two arrays containing signers are compared incorrectly.

Noncompliant Code Example

This noncompliant code example incorrectly uses the Object.equals() method to compare two arrays.

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.

Arrays.equals(arr1, arr2); // true

Risk Assessment

Using the equals() method or relational operators to compare array contents can produce incorrect results.

Automated Detection

The Coverity Prevent Version 5.0 BAD_EQ checker can detect the instance where The "==" operator is being used for equality of objects when in ideal case equal method should have been used. The "==" operator may consider objects different when the equals method considers them the same.

Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this guideline on the CERT website.

Bibliography

[[API 2006]]

EXP01-J. Do not compare String objects using equality or relational operators      04. Expressions (EXP)      EXP03-J. Do not use the equal and not equal operators to compare boxed primitives