rspec/rules/S2225/java/rule.adoc

== Why is this an issue?

Calling ``++toString()++`` or ``++clone()++`` on an object should always return a string or an object. Returning ``++null++`` instead contravenes the method's implicit contract.


=== Noncompliant code example

[source,java]
----
public String toString () {
  if (this.collection.isEmpty()) {
    return null; // Noncompliant
  } else {
    // ...
----

=== Compliant solution

[source,java]
----
public String toString () {
  if (this.collection.isEmpty()) {
    return "";
  } else {
    // ...
----

== Resources

* https://cwe.mitre.org/data/definitions/476[MITRE, CWE-476] - NULL Pointer Dereference
* https://wiki.sei.cmu.edu/confluence/x/aDdGBQ[CERT, EXP01-J.] - Do not use a null in a case where an object is required

ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

include::../message.adoc[]

'''
== Comments And Links
(visible only on this page)

include::../comments-and-links.adoc[]
endif::env-github,rspecator-view[]