uk.kludje

Class Meta<T>

java.lang.Object

uk.kludje.Meta<T>

Type Parameters:

T - the accessed type

public final class Meta<T>
extends java.lang.Object

Provides a basic meta-method builder for common Object method implementations.

Example that builds equals, hashCode and toString methods using the id, name and dateOfBirth properties:

 import uk.kludje.Meta;
 import java.time.LocalDate;
 import static uk.kludje.Meta.meta;

 public class PersonPojo {
   private static final Meta<PersonPojo> META = meta(PersonPojo.class)
 .                            longs($ -> $.id).objects($ -> $.name, $ -> $.dateOfBirth);

   private final long id;
   private final String name;
   private final LocalDate dateOfBirth;

   public PersonPojo(long id, String name, LocalDate dateOfBirth) {
     this.id = id;
     this.name = name;
     this.dateOfBirth = dateOfBirth;
   }

   public String getName() {
     return name;
   }

   public LocalDate getDateOfBirth() {
     return dateOfBirth;
   }

   public boolean equals(Object obj) {
     return META.equals(this, obj);
   }

   public int hashCode() {
     return META.hashCode(this);
   }

   public String toString() {
     return META.toString(this);
   }
 }
 

Note: arrays are treated as objects; use a decorator to provide alternative equals/hashCode/toString behaviour. For example, Google Guava's Bytes.asList(byte...).

Instances of this type are immutable and thread safe.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	Meta.BooleanGetter<T>
static interface	Meta.ByteGetter<T>
static interface	Meta.CharGetter<T>
static interface	Meta.DoubleGetter<T>
static interface	Meta.FloatGetter<T>
static interface	Meta.Getter<T> A functional interface for reading a property value.
static interface	Meta.IntGetter<T>
static interface	Meta.LongGetter<T>
static interface	Meta.ShortGetter<T>

Method Summary

Modifier and Type	Method and Description
Meta<T>	booleans(Meta.BooleanGetter<T>... getters)
Meta<T>	bytes(Meta.ByteGetter<T>... getters)
Meta<T>	chars(Meta.CharGetter<T>... getters)
Meta<T>	doubles(Meta.DoubleGetter<T>... getters)
boolean	equals(T t, java.lang.Object any) any is equal to t if it is of type T and all the properties defined by this type are equal.
Meta<T>	floats(Meta.FloatGetter<T>... getters)
int	hashCode(T t) Creates a hash of all values defined by the properties provided to this instance.
Meta<T>	ints(Meta.IntGetter<T>... getters)
Meta<T>	longs(Meta.LongGetter<T>... getters)
static <T> Meta<T>	meta()
Meta<T>	objects(Meta.Getter<T>... getters) Use to specify properties of type object that should be considered by this type.
Meta<T>	shorts(Meta.ShortGetter<T>... getters)
java.lang.String	toString(T t) Creates a string form of the type for debugging purposes.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

meta

public static <T> Meta<T> meta()

Type Parameters:

T - the type of class

Returns:

a new instance

objects

@SafeVarargs
public final Meta<T> objects(Meta.Getter<T>... getters)

Use to specify properties of type object that should be considered by this type. Do not use this method for primitive properties - alternatives have been provided. This method does not mutate the instance; it returns a new one.

Parameters:

getters - a vararg array of non-null getters

Returns:

a new instance

booleans

@SafeVarargs
public final Meta<T> booleans(Meta.BooleanGetter<T>... getters)

chars

@SafeVarargs
public final Meta<T> chars(Meta.CharGetter<T>... getters)

bytes

@SafeVarargs
public final Meta<T> bytes(Meta.ByteGetter<T>... getters)

shorts

@SafeVarargs
public final Meta<T> shorts(Meta.ShortGetter<T>... getters)

ints

@SafeVarargs
public final Meta<T> ints(Meta.IntGetter<T>... getters)

longs

@SafeVarargs
public final Meta<T> longs(Meta.LongGetter<T>... getters)

floats

@SafeVarargs
public final Meta<T> floats(Meta.FloatGetter<T>... getters)

doubles

@SafeVarargs
public final Meta<T> doubles(Meta.DoubleGetter<T>... getters)

equals

public boolean equals(T t,
                      java.lang.Object any)

any is equal to t if it is of type T and all the properties defined by this type are equal.

Parameters:

t - a non-null instance of type T

any - any object, including null

Returns:

true if the arguments are equal

hashCode

public int hashCode(T t)

Creates a hash of all values defined by the properties provided to this instance. The hashing formula is not specified.

Parameters:

t - the non-null instance to create a hash for

Returns:

the hash

toString

public java.lang.String toString(T t)

Creates a string form of the type for debugging purposes. The exact form is not specified.

Parameters:

t - the non-null instance to create a string form of

Returns:

debug string