Comparison of Object References Instead of Object Contents
The program compares object references instead of the contents of the objects themselves, preventing it from detecting equivalent objects.
For example, in Java, comparing objects using == usually produces deceptive results, since the == operator compares object references rather than values; often, this means that using == for strings is actually comparing the strings' references, not their values.
The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.
Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.
In the example below, two Java String objects are declared and initialized with the same string values. An if statement is used to determine if the strings are equivalent.
However, the if statement will not be executed as the strings are compared using the "==" operator. For Java objects, such as String objects, the "==" operator compares object references, not object values. While the two String objects above contain the same string values, they refer to different object references, so the System.out.println statement will not be executed. To compare object values, the previous code could be modified to use the equals method:
In the following Java example, two BankAccount objects are compared in the isSameAccount method using the == operator.
Using the == operator to compare objects may produce incorrect or deceptive results by comparing object references rather than values. The equals() method should be used to ensure correct results or objects should contain a member variable that uniquely identifies the object.
The following example shows the use of the equals() method to compare the BankAccount objects and the next example uses a class get method to retrieve the bank account number that uniquely identifies the BankAccount object to compare the objects.
Weaknesses in this category are related to the CISQ Quality Measures for Reliability. Presence of these weaknesses could reduce the reliability of the software.
Weaknesses in this category are related to the rules and recommendations in the Expressions (EXP) section of the SEI CERT Oracle Secure Coding Standard for Java.
This category identifies Software Fault Patterns (SFPs) within the Design cluster.
This view (slice) covers all the elements in CWE.
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This view (slice) lists weaknesses that can be introduced during implementation.