compact1, compact2, compact3
java.util.concurrent.atomic

## Class AtomicMarkableReference<V>

- java.lang.Object
- - java.util.concurrent.atomic.AtomicMarkableReference<V>

- Type Parameters:
    `V` - The type of object referred to by this reference

      public class AtomicMarkableReference<V>
      extends Object

  An `AtomicMarkableReference` maintains an object reference along with a mark bit, that can be updated atomically.

  Implementation note: This implementation maintains markable references by creating internal objects representing "boxed" [reference, boolean] pairs.

  Since:
    1.5

- - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `AtomicMarkableReference(V initialRef, boolean initialMark)` | Creates a new `AtomicMarkableReference` with the given initial values.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `boolean` | `attemptMark(V expectedReference, boolean newMark)` | Atomically sets the value of the mark to the given update value if the current reference is `==` to the expected reference.
    `boolean` | `compareAndSet(V expectedReference, V newReference, boolean expectedMark, boolean newMark)` | Atomically sets the value of both the reference and mark to the given update values if the current reference is `==` to the expected reference and the current mark is equal to the expected mark.
    `V` | `get(boolean[] markHolder)` | Returns the current values of both the reference and the mark.
    `V` | `getReference()` | Returns the current value of the reference.
    `boolean` | `isMarked()` | Returns the current value of the mark.
    `void` | `set(V newReference, boolean newMark)` | Unconditionally sets the value of both the reference and mark.
    `boolean` | `weakCompareAndSet(V expectedReference, V newReference, boolean expectedMark, boolean newMark)` | Atomically sets the value of both the reference and mark to the given update values if the current reference is `==` to the expected reference and the current mark is equal to the expected mark.

    - ### Methods inherited from class java.lang.Object

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

- - ### Constructor Detail

    - #### AtomicMarkableReference

          public AtomicMarkableReference(V initialRef,
                                         boolean initialMark)

      Creates a new `AtomicMarkableReference` with the given initial values.
      Parameters:
        `initialRef` - the initial reference
        `initialMark` - the initial mark

  - ### Method Detail

    - #### getReference

          public V getReference()

      Returns the current value of the reference.
      Returns:
        the current value of the reference

    - #### isMarked

          public boolean isMarked()

      Returns the current value of the mark.
      Returns:
        the current value of the mark

    - #### get

          public V get(boolean[] markHolder)

      Returns the current values of both the reference and the mark. Typical usage is `boolean[1] holder; ref = v.get(holder);` .
      Parameters:
        `markHolder` - an array of size of at least one. On return, `markholder[0]` will hold the value of the mark.
      Returns:
        the current value of the reference

    - #### weakCompareAndSet

          public boolean weakCompareAndSet(V expectedReference,
                                           V newReference,
                                           boolean expectedMark,
                                           boolean newMark)

      Atomically sets the value of both the reference and mark to the given update values if the current reference is `==` to the expected reference and the current mark is equal to the expected mark.

      May fail spuriously and does not provide ordering guarantees, so is only rarely an appropriate alternative to `compareAndSet`.

      Parameters:
        `expectedReference` - the expected value of the reference
        `newReference` - the new value for the reference
        `expectedMark` - the expected value of the mark
        `newMark` - the new value for the mark
      Returns:
        `true` if successful

    - #### compareAndSet

          public boolean compareAndSet(V expectedReference,
                                       V newReference,
                                       boolean expectedMark,
                                       boolean newMark)

      Atomically sets the value of both the reference and mark to the given update values if the current reference is `==` to the expected reference and the current mark is equal to the expected mark.
      Parameters:
        `expectedReference` - the expected value of the reference
        `newReference` - the new value for the reference
        `expectedMark` - the expected value of the mark
        `newMark` - the new value for the mark
      Returns:
        `true` if successful

    - #### set

          public void set(V newReference,
                          boolean newMark)

      Unconditionally sets the value of both the reference and mark.
      Parameters:
        `newReference` - the new value for the reference
        `newMark` - the new value for the mark

    - #### attemptMark

          public boolean attemptMark(V expectedReference,
                                     boolean newMark)

      Atomically sets the value of the mark to the given update value if the current reference is `==` to the expected reference. Any given invocation of this operation may fail (return `false`) spuriously, but repeated invocation when the current value holds the expected value and no other thread is also attempting to set the value will eventually succeed.
      Parameters:
        `expectedReference` - the expected value of the reference
        `newMark` - the new value for the mark
      Returns:
        `true` if successful

Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Copyright © 1993, 2026, Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.