no.digipost.util

Class JustALong

java.lang.Object

no.digipost.util.JustALong

Type Parameters:

T - The type of wrapped value. Should be an immutable value-type.

All Implemented Interfaces:

Serializable

public abstract class JustALong
extends Object
implements Serializable

Base class for creating simple "typed long" value classes, for cases when you do not want to pass around simple longs for numbers that has certain (business-) semantics in your application, even though a long does adequately express the value. By extending this class you do not have to implement the equals and hashcode. You would not refer to this class other than with an extends JustALong decalaration in your class definition.

This is a special case implementation of JustA to avoid the boxing cost for primitive longs. The typical use for this are for ids, and classes where instances are uniquely distinguished by their long ids, and equals/hashcode will exercise correct behavior when only operating on the id. Any additional fields in an extending class should usually be declared final.

A common pattern for using this class would be:

 interface WithId {

   static JustAnId of(long id) {
     return new JustAnId(id);
   }

   final class JustAnId extends JustALong implements WithId {

      private JustAnId(String id) {
        super(id);
      }

      public long getId() {
        return theValue;
      }
    }


    long getId();
 }

See Also:

{@code JustA} is the generic version for any (reference-) type., Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected long	theLong

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	JustALong(long theValue)
protected	JustALong(long theValue, SerializableFunction<? super Long,String> valueToString)
protected	JustALong(long theValue, String description)
protected	JustALong(long theValue, String description, SerializableFunction<? super Long,String> valueToString)

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object obj)
int	hashCode()
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

theLong

protected final long theLong

Constructor Detail

JustALong

protected JustALong(long theValue)

JustALong

protected JustALong(long theValue,
                    String description)

JustALong

protected JustALong(long theValue,
                    SerializableFunction<? super Long,String> valueToString)

JustALong

protected JustALong(long theValue,
                    String description,
                    SerializableFunction<? super Long,String> valueToString)

Method Detail

equals

public final boolean equals(Object obj)

Overrides:

equals in class Object

hashCode

public final int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object