org.apache.gobblin.util

Class Either<S,T>

java.lang.Object

org.apache.gobblin.util.Either<S,T>

Type Parameters:

S - first possible type for the value.

T - second possible type for the value.

Direct Known Subclasses:

Either.Left, Either.Right

public abstract class Either<S,T>
extends Object

Represents a value of one of two possible types. Similar to Scala's Either. Each instance of Either is of type Either.Left or Either.Right depending of the class of its value.

This class is useful when a class has two different states, each of which depends on a variable of a different type (for example a String name or Numeric id). While the normal pattern is to have two variables, only one of which is set, or two Optionals, only one of which is present, that pattern does not protect from having none or both variables set by programming errors. Instead, a single instance of Either can be used, which guarantees exactly one type will be set.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Either.Left<S,T> An instance of Either with value of type S.
static class	Either.Right<S,T> An instance of Either with value of type T.

Field Summary

Fields

Modifier and Type	Field and Description
protected com.google.common.base.Optional<S>	s
protected com.google.common.base.Optional<T>	t

Constructor Summary

Constructors

Constructor and Description
Either()

Method Summary

Modifier and Type	Method and Description
Object	get() Get the value of this Either instance, returned as class Object.
static <S,T> Either<S,T>	left(S left) Create an instance of Either with value of type S.
static <S,T> Either<S,T>	right(T right) Create an instance of Either with value of type T.

Methods inherited from class java.lang.Object

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

Field Detail

s

protected final com.google.common.base.Optional<S> s

t

protected final com.google.common.base.Optional<T> t

Constructor Detail

Either

public Either()

Method Detail

left

public static <S,T> Either<S,T> left(S left)

Create an instance of Either with value of type S.

Parameters:

left - value of this instance.

Returns:

an instance of Either.Left.

right

public static <S,T> Either<S,T> right(T right)

Create an instance of Either with value of type T.

Parameters:

right - value of this instance.

Returns:

an instance of Either.Right.

get

public Object get()

Get the value of this Either instance, returned as class Object. To get a strongly typed return, check the specific type of Either and call Either.Left.getLeft() or Either.Right.getRight().

Returns:

value as an instance of Object.