org.apache.cayenne.event

## Class EventSubject

- java.lang.Object
- - org.apache.cayenne.event.EventSubject

- All Implemented Interfaces:
    Serializable

      public class EventSubject
      extends Object
      implements Serializable

  This class encapsulates the String that is used to identify the subject that a listener is interested in. Using plain Strings causes several severe problems:
  - it's easy to misspell a subject, leading to undesired behaviour at runtime that is hard to debug.
  - in systems with many different subjects there is no safeguard for defining the same subject twice for different purposes. This is especially true in a distributed setting.
  See Also:
    Serialized Form

- - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `EventSubject(String fullSubjectName)` Protected constructor for new subjects.

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `boolean` | `equals(Object obj)`
    `static EventSubject` | `getSubject(Class<?> subjectOwner, String subjectName)` Returns an event subject identified by the given owner and subject name.
    `String` | `getSubjectName()`
    `int` | `hashCode()`
    `String` | `toString()`

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

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### Constructor Detail

    - #### EventSubject

          protected EventSubject(String fullSubjectName)

      Protected constructor for new subjects.
      Parameters:
        `fullSubjectName` - the name of the new subject to be created

  - ### Method Detail

    - #### getSubject

          public static EventSubject getSubject(Class<?> subjectOwner,
                                                String subjectName)

      Returns an event subject identified by the given owner and subject name.
      Parameters:
        `subjectOwner` - the Class used for uniquely identifying this subject
        `subjectName` - a String used as name, e.g. "MyEventTopic"
      Throws:
        `IllegalArgumentException` - if subjectOwner/subjectName are `null` or subjectName is empty.

    - #### equals

          public boolean equals(Object obj)

      Overrides:
        `equals` in class `Object`

    - #### hashCode

          public int hashCode()

      Overrides:
        `hashCode` in class `Object`

    - #### getSubjectName

          public String getSubjectName()

    - #### toString

          public String toString()

      Overrides:
        `toString` in class `Object`
      Returns:
        a String in the form `<ClassName 0x123456> SomeName`
      See Also:
        `Object.toString()`

Copyright © 2001–2023 Apache Cayenne. All rights reserved.