Extend a class that overrides ``++equals++`` and add fields without overriding ``++equals++`` in the subclass, and you run the risk of non-equivalent instances of your subclass being seen as equal, because only the superclass fields will be considered in the equality test.


This rule looks for classes that do all of the following:

* extend classes that override ``++equals++``.
* do not themselves override ``++equals++``.
* add fields.


== Noncompliant Code Example

[source,java]
----
public class Fruit {
  private Season ripe;

  public boolean equals(Object obj) {
    if (obj == this) {
      return true;
    }
    if (this.class != obj.class) {
      return false;
    }
    Fruit fobj = (Fruit) obj;
    if (ripe.equals(fobj.getRipe()) {
      return true;
    }
    return false;
  }
}

public class Raspberry extends Fruit {  // Noncompliant; instances will use Fruit's equals method
  private Color ripeColor;
}
----


== Compliant Solution

[source,java]
----
public class Fruit {
  private Season ripe;

  public boolean equals(Object obj) {
    if (obj == this) {
      return true;
    }
    if (this.class != obj.class) {
      return false;
    }
    Fruit fobj = (Fruit) obj;
    if (ripe.equals(fobj.getRipe()) {
      return true;
    }
    return false;
  }
}

public class Raspberry extends Fruit {
  private Color ripeColor;

  public boolean equals(Object obj) {
    if (! super.equals(obj)) {
      return false;
    }
    Raspberry fobj = (Raspberry) obj;
    if (ripeColor.equals(fobj.getRipeColor()) {  // added fields are tested
      return true;
    }
    return false;
  }
}
----

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== Implementation Specification
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include::message.adoc[]

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