The readObject() method must not call any overridable methods. Invoking overridable methods from the readObject() method can provide the overriding method with access to the object's state before it is fully initialized. This premature access is possible because, in deserialization, readObject plays the role of object constructor and therefore object initialization is not complete until readObject exits . Also see the related rule (see also MET06-J. Do not invoke overridable methods in clone()).
Noncompliant Code Example
This noncompliant code example invokes an overridable method from the readObject() method. :
| Code Block | ||
|---|---|---|
| ||
private void readObject(final ObjectInputStream stream)
throws IOException, ClassNotFoundException {
overridableMethod();
stream.defaultReadObject();
}
public void overridableMethod() {
// ...
}
|
...
This compliant solution removes the call to the overridable method. When removing such calls is infeasible, declare the method private or final.
| Code Block | ||
|---|---|---|
| ||
private void readObject(final ObjectInputStream stream)
throws IOException, ClassNotFoundException {
stream.defaultReadObject();
}
|
Exceptions
unmigratedSER09-wikiJ-markup*SER09-EX0:* The {{readObject()}} method may invoke the overridable methods {{defaultReadObject()}} and {{readFields()}} in class {{java.io.ObjectInputStream}} \ [[SCG 2009|AA. References#SCG 09]\].
Risk Assessment
Invoking overridable methods from the readObject() method can lead to initialization errors.
Rule | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
SER09-J |
Low |
Probable |
Medium | P4 | L3 |
Automated Detection
| Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Parasoft Jtest |
| CERT.SER09.VREADOBJ | Do not invoke overridable methods from the readObject() method |
Related Guidelines
Guideline 7-4 / OBJECT-4 |
: Prevent constructors from calling methods that can be overridden |
Bibliography
...
[
2006
[API |
AA. References#API 06]]
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[[Bloch 2008
AA. References#Bloch 08]]
Item 17. Design and document for inheritance or else prohibit it
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2014] | |
Item 17, "Design and Document for Inheritance or Else Prohibit It" | |
| [SCG 2009] |
...