Those who use hibernate for database access know that you need to provide an information that this object is a hibernate object. To do so you typically need to annotate your object with @Entity. It’s not a problem although if we speak about some large system. In large systems we have typically a number of instances of the same object that represent the same table in different contexts and packages. And here we need this: to give each object unique name.
Example:

@Entity(name="person.usa")
class Person {
   ...
}

This PMD rule shows how to check if a hibernate object have a name.

<![CDATA[
     //Annotation/NormalAnnotation[
     (
           Name/@Image='Entity'
           and
           not
           (
                 MemberValuePairs/MemberValuePair/@Image='name'
                 and
                 //PrimaryExpression/PrimaryPrefix[contains(Literal/@Image,'.')]
           )
     )
]]]>

I was trying to solve a problem of resetting a focus if the parent changes. I had different buttons that show the same .mxml-form but with different data. The problem was that I needed the focus to be on the first date-field whenever the form is shown so that the user can begin typing data right away.

<mx:HBox>
       <mx:Button id="noData" click="showPanelWithNoData()" />
       <mx:Button id="someData" click="showPanelWithSomeData()" />
       <mx:Button id="withData" click="showPanelWithData()" />

       <myCustomForm:DataForm width="100%" />
</mx:HBox>

So for each time one of the buttons is pushed I need the focus to be on myDate-field. To solve the problem I used “updateComplete“-property of the field.

DataForm.mxml

<?xml version="1.0" encoding="utf-8"?>
<DataForm
    xmlns:mx="http://www.adobe.com/2006/mxml">
    <mx:Script>
        <![CDATA[
            import mx.managers.FocusManager;

            private function resetFocus():void {
                if (focusManager != null && myDate.focusManager != null) {
                    focusManager.setFocus(myDate);
                }
            }
        ]]>
    </mx:Script>

    <mx:FormItem>
        <mx:TextField id="myDate"
            updateComplete="resetFocus()"/>
    </mx:FormItem>

</DataForm>

1. Use the == to check if the argument is a reference to this object.

2. Use the instanceof operator to check if the argument has the correct type.

3. Cast the argument to the correct type.

4. For each “significant” field in the class, check if that field of the argument matches the corresponding field of this object.

5. Always override hashCode when you override equals.

6. Don’t substitute another type for Object in the equals declaration.

7. Write unit-test.

   @Override
   public boolean equals(Object obj) {
      if(obj == this) {
         return true;
      }
      if(!(obj instanceof Person)) {
          return false;
      }
      Person p = (Person)obj;
      return p.name.equals(name)
             p.birthday.equals(birthday)
             p.personNumber == personNumber;
      }

Ref.”Effective Java” by Joshua Bloch

Enother example with hashCode and toString:

    @Override
    public boolean equals(Object obj) {
        if (obj == null || !obj.getClass().isInstance(this)) {
            return false;
        }
        Beregning b = (Beregning) obj;

        return new EqualsBuilder()
                .append(simulertPensjon, b.getSimulertPensjon())
                .append(linjer.size(), b.getLinjer().size()).isEquals();
    }

    @Override
    public int hashCode() {
        return new HashCodeBuilder().append(simulertPensjon).append(linjer).hashCode();
    }

    @Override
    public String toString() {
        return new ToStringBuilder(this, ToStringStyle.SHORT_PREFIX_STYLE)
        .append("simulertPensjon", simulertPensjon)
        .append("antall linjer", linjer.size()).toString();
    }