T
- the type of the object managed by this initializer classpublic class AtomicSafeInitializer<T> extends AbstractConcurrentInitializer<T,ConcurrentException>
ConcurrentInitializer
implementation which is similar
to AtomicInitializer
, but ensures that the AbstractConcurrentInitializer.initialize()
method is called only once.
As AtomicInitializer
this class is based on atomic variables, so it
can create an object under concurrent access without synchronization.
However, it implements an additional check to guarantee that the
AbstractConcurrentInitializer.initialize()
method which actually creates the object cannot be
called multiple times.
Because of this additional check this implementation is slightly less
efficient than AtomicInitializer
, but if the object creation in the
initialize()
method is expensive or if multiple invocations of
initialize()
are problematic, it is the better alternative.
From its semantics this class has the same properties as
LazyInitializer
. It is a "save" implementation of the lazy
initializer pattern. Comparing both classes in terms of efficiency is
difficult because which one is faster depends on multiple factors. Because
AtomicSafeInitializer
does not use synchronization at all it probably
outruns LazyInitializer
, at least under low or moderate concurrent
access. Developers should run their own benchmarks on the expected target
platform to decide which implementation is suitable for their specific use
case.
Modifier and Type | Class and Description |
---|---|
static class |
AtomicSafeInitializer.Builder<I extends AtomicSafeInitializer<T>,T>
Builds a new instance.
|
AbstractConcurrentInitializer.AbstractBuilder<I extends AbstractConcurrentInitializer<T,E>,T,B extends AbstractConcurrentInitializer.AbstractBuilder<I,T,B,E>,E extends Exception>
NUL
Constructor and Description |
---|
AtomicSafeInitializer()
Constructs a new instance.
|
Modifier and Type | Method and Description |
---|---|
static <T> AtomicSafeInitializer.Builder<AtomicSafeInitializer<T>,T> |
builder()
Creates a new builder.
|
T |
get()
Gets (and initialize, if not initialized yet) the required object
|
protected ConcurrentException |
getTypedException(Exception e)
Gets an Exception with a type of E as defined by a concrete subclass of this class.
|
boolean |
isInitialized()
Tests whether this instance is initialized.
|
close, initialize
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
nul
public AtomicSafeInitializer()
public static <T> AtomicSafeInitializer.Builder<AtomicSafeInitializer<T>,T> builder()
T
- the type of object to build.public final T get() throws ConcurrentException
ConcurrentException
- if the initialization of the object causes an
exceptionprotected ConcurrentException getTypedException(Exception e)
getTypedException
in class AbstractConcurrentInitializer<T,ConcurrentException>
e
- The actual exception that was thrownpublic boolean isInitialized()
isInitialized
in class AbstractConcurrentInitializer<T,ConcurrentException>
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