Package org.apache.lucene.util

Class SetOnce<T>

java.lang.Object
org.apache.lucene.util.SetOnce<T>
All Implemented Interfaces:
Cloneable
public final class SetOnce<T> extends Object implements Cloneable
A convenient class which offers a semi-immutable object wrapper implementation which allows one to set the value of an object exactly once, and retrieve it many times. If set(Object) is called more than once, SetOnce.AlreadySetException is thrown and the operation will fail.
WARNING: This API is experimental and might change in incompatible ways in the next release.

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    static final class 
    SetOnce.AlreadySetException
    Thrown when set(Object) is called more than once.

  • Constructor Summary

    Constructors
    Constructor
    Description
    SetOnce()
    A default constructor which does not set the internal object, and allows setting it by calling set(Object).
    SetOnce(T obj)
    Creates a new instance with the internal object set to the given object.

  • Method Summary

    Modifier and Type
    Method
    Description
    final T
    get()
    Returns the object set by set(Object).
    final void
    set(T obj)
    Sets the given object.
    final boolean
    trySet(T obj)
    Sets the given object if none was set before.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

  • Method Details

    • set

      public final void set(T obj)
      Sets the given object. If the object has already been set, an exception is thrown.

    • trySet

      public final boolean trySet(T obj)
      Sets the given object if none was set before.
      Returns:
      true if object was set successfully, false otherwise

    • get

      public final T get()
      Returns the object set by set(Object).