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AtomicSafeInitializer

public class org.apache.commons.lang3.concurrent.AtomicSafeInitializer<T> extends AbstractConcurrentInitializer<T, ConcurrentException>

A specialized ConcurrentInitializer implementation which is similar to AtomicInitializer, but ensures that the #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 #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.

Parameters:

<T> – The type of the object managed by this initializer class

Since:

3.0

Constructors

AtomicSafeInitializer()

Constructs a new instance.

public AtomicSafeInitializer()

Constructs a new instance.

Methods

builder()	Creates a new builder.
get()	Gets (and initialize, if not initialized yet) the required object.
getTypedException(Exception)	Gets an Exception with a type of E as defined by a concrete subclass of this class.
isInitialized()	Tests whether this instance is initialized.

public static <T> AtomicSafeInitializer.Builder<AtomicSafeInitializer<T>, T> builder()

Creates a new builder.

Type parameters:

<T> – The type of object to build.

Returns:

A new builder.

Since:

3.14.0

@Override public final T get() throws ConcurrentException

Gets (and initialize, if not initialized yet) the required object.

Returns:

lazily initialized object.

Throws:

org.apache.commons.lang3.concurrent.ConcurrentException – Thrown if the initialization of the object causes an exception.

@Override protected ConcurrentException getTypedException(Exception e)

Gets an Exception with a type of E as defined by a concrete subclass of this class.

Parameters:

e – The actual exception that was thrown.

Returns:

A new exception with the actual type of E, that wraps e.

@Override public boolean isInitialized()

Tests whether this instance is initialized. Once initialized, always returns true.

Returns:

whether this instance is initialized. Once initialized, always returns true.

Since:

3.14.0