Maybe (Apache Brooklyn)

java.lang.Object
- brooklyn.util.guava.Maybe<T>

All Implemented Interfaces:

com.google.common.base.Supplier<T>, java.io.Serializable

Direct Known Subclasses:

Maybe.Absent, Maybe.AbstractPresent, Maybe.SoftlyPresent
```
public abstract class Maybe<T>
extends java.lang.Object
implements java.io.Serializable, com.google.common.base.Supplier<T>
```
Like Guava Optional but permitting null and permitting errors to be thrown.

See Also:
Serialized Form

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`Maybe.Absent<T>`
`static class`	`Maybe.AbstractPresent<T>`
`static class`	`Maybe.Present<T>`
`static class`	`Maybe.SoftlyPresent<T>`

Constructor Summary

Constructors
Constructor and Description

Maybe()

Constructors
Constructor and Description
`Maybe()`

Method Summary

Methods
Modifier and Type	Method and Description
`static <T> Maybe<T>`	`absent()`
`static <T> Maybe<T>`	`absent(java.lang.String message)` Creates an absent whose get throws an `IllegalStateException` with the indicated message.
`static <T> Maybe<T>`	`absent(java.lang.String message, java.lang.Throwable cause)` Creates an absent whose get throws an `IllegalStateException` with the indicated message and underlying cause.
`static <T> Maybe<T>`	`absent(com.google.common.base.Supplier<? extends java.lang.RuntimeException> exceptionSupplier)` Creates an absent whose get throws an `RuntimeException` generated on demand from the given supplier
`static <T> Maybe<T>`	`absent(java.lang.Throwable cause)` Creates an absent whose get throws an `IllegalStateException` with the indicated cause.
`java.util.Set<T>`	`asSet()`
`boolean`	`equals(java.lang.Object obj)`
`static <T> Maybe<T>`	`fromNullable(T value)` like `Optional.fromNullable(Object)`, returns absent if the argument is null
`abstract T`	`get()`
`int`	`hashCode()`
`boolean`	`isAbsent()`
`boolean`	`isAbsentOrNull()`
`abstract boolean`	`isPresent()`
`boolean`	`isPresentAndNonNull()`
`static <T> Maybe<T>`	`next(java.util.Iterator<T> iterator)` returns a Maybe containing the next element in the iterator, or absent if none
`static <T> Maybe<T>`	`of(com.google.common.base.Optional<T> value)`
`static <T> Maybe<T>`	`of(com.google.common.base.Supplier<T> value)`
`static <T> Maybe<T>`	`of(T value)`
`Maybe<T>`	`or(Maybe<T> nextValue)`
`T`	`or(com.google.common.base.Supplier<T> nextValue)`
`T`	`or(T nextValue)`
`T`	`orNull()`
`static <T> java.lang.Iterable<T>`	`presentInstances(java.lang.Iterable<? extends Maybe<? extends T>> maybes)` Returns the value of each present instance from the supplied `maybes`, in order, skipping over occurrences of `absent()`.
`static <T> Maybe<T>`	`soft(T value)` creates an instance wrapping a `SoftReference`, so it might go absent later on
`static <T> Maybe<T>`	`softThen(T value, Maybe<T> ifEmpty)` creates an instance wrapping a `SoftReference`, using the second item given if lost
`java.lang.String`	`toString()`
`<V> Maybe<V>`	`transform(com.google.common.base.Function<? super T,V> f)`

Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait

Constructor Detail
- Maybe
```
public Maybe()
```

Method Detail

absent
```
public static <T> Maybe<T> absent()
```

absent
```
public static <T> Maybe<T> absent(java.lang.String message)
```
Creates an absent whose get throws an IllegalStateException with the indicated message. Both stack traces (the cause and the callers) are provided, which can be quite handy.

absent
```
public static <T> Maybe<T> absent(java.lang.Throwable cause)
```
Creates an absent whose get throws an IllegalStateException with the indicated cause. Both stack traces (the cause and the callers) are provided, which can be quite handy.

absent
```
public static <T> Maybe<T> absent(java.lang.String message,
                  java.lang.Throwable cause)
```
Creates an absent whose get throws an IllegalStateException with the indicated message and underlying cause. Both stack traces (the cause and the callers) are provided, which can be quite handy.

absent

public static <T> Maybe<T> absent(com.google.common.base.Supplier<? extends java.lang.RuntimeException> exceptionSupplier)

Creates an absent whose get throws an RuntimeException generated on demand from the given supplier

of

public static <T> Maybe<T> of(@Nullable
              T value)

soft
```
public static <T> Maybe<T> soft(T value)
```
creates an instance wrapping a SoftReference, so it might go absent later on

softThen

public static <T> Maybe<T> softThen(T value,
                    Maybe<T> ifEmpty)

creates an instance wrapping a SoftReference, using the second item given if lost

fromNullable

public static <T> Maybe<T> fromNullable(@Nullable
                        T value)

like Optional.fromNullable(Object), returns absent if the argument is null

of

public static <T> Maybe<T> of(com.google.common.base.Optional<T> value)

of

public static <T> Maybe<T> of(com.google.common.base.Supplier<T> value)

next
```
public static <T> Maybe<T> next(java.util.Iterator<T> iterator)
```
returns a Maybe containing the next element in the iterator, or absent if none

isPresent
```
public abstract boolean isPresent()
```

get
```
public abstract T get()
```
Specified by:

get in interface com.google.common.base.Supplier<T>

isAbsent
```
public boolean isAbsent()
```

isAbsentOrNull
```
public boolean isAbsentOrNull()
```

isPresentAndNonNull
```
public boolean isPresentAndNonNull()
```

or
```
public T or(T nextValue)
```

or

public Maybe<T> or(Maybe<T> nextValue)

or

public T or(com.google.common.base.Supplier<T> nextValue)

orNull
```
public T orNull()
```

asSet
```
public java.util.Set<T> asSet()
```

transform

public <V> Maybe<V> transform(com.google.common.base.Function<? super T,V> f)

presentInstances
```
@Beta
public static <T> java.lang.Iterable<T> presentInstances(java.lang.Iterable<? extends Maybe<? extends T>> maybes)
```
Returns the value of each present instance from the supplied maybes, in order, skipping over occurrences of absent(). Iterators are unmodifiable and are evaluated lazily.

See Also:
Optional.presentInstances(Iterable)

toString
```
public java.lang.String toString()
```
Overrides:

toString in class java.lang.Object

hashCode
```
public int hashCode()
```
Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object obj)

Overrides:: equals in class java.lang.Object

Class Maybe<T>

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Maybe

Method Detail

absent

absent

absent

absent

absent

of

soft

softThen

fromNullable

of

of

next

isPresent

get

isAbsent

isAbsentOrNull

isPresentAndNonNull

or

or

or

orNull

asSet

transform

presentInstances

toString

hashCode

equals