MergeContext (Red Hat JBoss Enterprise Application Platform 7.4.7.GA public API)

java.lang.Object
- org.hibernate.event.internal.MergeContext

All Implemented Interfaces:

Map
```
public class MergeContext
extends Object
implements Map
```
MergeContext is a Map implementation that is intended to be used by a merge event listener to keep track of each entity being merged and their corresponding managed result. Entities to be merged may to be added to the MergeContext before the merge operation has cascaded to that entity. "Merge entity" and "mergeEntity" method parameter refer to an entity that is (or will be) merged via Session.merge(Object mergeEntity). "Managed entity" and "managedEntity" method parameter refer to the managed entity that is the result of merging an entity. A merge entity can be transient, detached, or managed. If it is managed, then it must be the same as its associated entity result. If put(Object mergeEntity, Object managedEntity) is called, and this MergeContext already contains an entry with a different entity as the key, but with the same (managedEntity) value, this means that multiple entity representations for the same persistent entity are being merged. If this happens, EntityCopyObserver.entityCopyDetected( Object managedEntity, Object mergeEntity1, Object mergeEntity2, org.hibernate.event.spi.EventSource) will be called. It is up to that method to determine the property course of action for this situation. There are several restrictions.
- Methods that return collections (e.g., keySet(), values(), entrySet()) return an unmodifiable view of the collection;
- If managedEntity or put(Object mergeEntity, Object managedEntity, boolean isOperatedOn) is executed and this MergeMap already contains a cross-reference for mergeEntity, then managedEntity must be the same as what is already associated with mergeEntity in this MergeContext.
- If putAll(Map map) is executed, the previous restriction applies to each entry in the Map;
- The remove(Object) operation is not supported; The only way to remove data from a MergeContext is by calling clear();
- the Map returned by invertMap() will only contain the managed-to-merge entity cross-reference to its "newest" (most recently added) merge entity.
The following method is intended to be used by a merge event listener (and other classes) in the same package to add a merge entity and its corresponding managed entity to a MergeContext and indicate if the merge operation is being performed on the merge entity yet.
put(Object mergeEntity, Object managedEntity, boolean isOperatedOn)
The following method is intended to be used by a merge event listener (and other classes) in the same package to indicate whether the merge operation is being performed on a merge entity already in the MergeContext: setOperatedOn(Object mergeEntity, boolean isOperatedOn)
Author:

Gail Badner

Nested Class Summary
- Nested classes/interfaces inherited from interface java.util.Map
  Map.Entry<K,V>

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`clear()` Clears the MergeContext.
`boolean`	`containsKey(Object mergeEntity)` Returns true if this MergeContext contains a cross-reference for the specified merge entity to a managed entity result.
`boolean`	`containsValue(Object managedEntity)` Returns true if this MergeContext contains a cross-reference from the specified managed entity to a merge entity.
`Set`	`entrySet()` Returns an unmodifiable set view of the merge-to-managed entity cross-references contained in this MergeContext.
`Object`	`get(Object mergeEntity)` Returns the managed entity associated with the specified merge Entity.
`Map`	`invertMap()` Returns an unmodifiable map view of the managed-to-merge entity cross-references.
`boolean`	`isEmpty()` Returns true if this MergeContext contains no merge-to-managed entity cross-references.
`boolean`	`isOperatedOn(Object mergeEntity)` Returns true if the listener is performing the merge operation on the specified merge entity.
`Set`	`keySet()` Returns an unmodifiable set view of the merge entities contained in this MergeContext
`Object`	`put(Object mergeEntity, Object managedEntity)` Associates the specified merge entity with the specified managed entity result in this MergeContext.
`void`	`putAll(Map map)` Copies all of the mappings from the specified Map to this MergeContext.
`Object`	`remove(Object mergeEntity)` The remove operation is not supported.
`int`	`size()` Returns the number of merge-to-managed entity cross-references in this MergeContext
`Collection`	`values()` Returns an unmodifiable Set view of managed entities contained in this MergeContext.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Map
compute, computeIfAbsent, computeIfPresent, equals, forEach, getOrDefault, hashCode, merge, putIfAbsent, remove, replace, replace, replaceAll

- Method Detail
  - clear
```
public void clear()
```
    Clears the MergeContext.
    
    Specified by:
    
    clear in interface Map
  - containsKey
```
public boolean containsKey(Object mergeEntity)
```
    Returns true if this MergeContext contains a cross-reference for the specified merge entity to a managed entity result.
    
    Specified by:
    
    containsKey in interface Map
    
    Parameters:
    
    mergeEntity - must be non-null
    
    Returns:
    
    true if this MergeContext contains a cross-reference for the specified merge entity
    
    Throws:
    
    NullPointerException - if mergeEntity is null
  - containsValue
```
public boolean containsValue(Object managedEntity)
```
    Returns true if this MergeContext contains a cross-reference from the specified managed entity to a merge entity.
    
    Specified by:
    
    containsValue in interface Map
    
    Parameters:
    
    managedEntity - must be non-null
    
    Returns:
    
    true if this MergeContext contains a cross-reference from the specified managed entity to a merge entity
    
    Throws:
    
    NullPointerException - if managedEntity is null
  - entrySet
```
public Set entrySet()
```
    Returns an unmodifiable set view of the merge-to-managed entity cross-references contained in this MergeContext.
    
    Specified by:
    
    entrySet in interface Map
    
    Returns:
    
    an unmodifiable set view of the merge-to-managed entity cross-references contained in this MergeContext
    
    See Also:
    
    Collections.unmodifiableSet(java.util.Set)
  - get
```
public Object get(Object mergeEntity)
```
    Returns the managed entity associated with the specified merge Entity.
    
    Specified by:
    
    get in interface Map
    
    Parameters:
    
    mergeEntity - the merge entity; must be non-null
    
    Returns:
    
    the managed entity associated with the specified merge Entity
    
    Throws:
    
    NullPointerException - if mergeEntity is null
  - isEmpty
```
public boolean isEmpty()
```
    Returns true if this MergeContext contains no merge-to-managed entity cross-references.
    
    Specified by:
    
    isEmpty in interface Map
    
    Returns:
    
    true if this MergeContext contains no merge-to-managed entity cross-references.
  - keySet
```
public Set keySet()
```
    Returns an unmodifiable set view of the merge entities contained in this MergeContext
    
    Specified by:
    
    keySet in interface Map
    
    Returns:
    
    an unmodifiable set view of the merge entities contained in this MergeContext
    
    See Also:
    
    Collections.unmodifiableSet(java.util.Set)
  - put
```
public Object put(Object mergeEntity,
                  Object managedEntity)
```
    Associates the specified merge entity with the specified managed entity result in this MergeContext. If this MergeContext already contains a cross-reference for mergeEntity when this method is called, then managedEntity must be the same as what is already associated with mergeEntity.
    This method assumes that the merge process is not yet operating on mergeEntity. Later when mergeEntity enters the merge process, setOperatedOn(Object, boolean) should be called.
    
    Specified by:
    
    put in interface Map
    
    Parameters:
    
    mergeEntity - the merge entity; must be non-null
    
    managedEntity - the managed entity result; must be non-null
    
    Returns:
    
    previous managed entity associated with specified merge entity, or null if there was no mapping for mergeEntity.
    
    Throws:
    
    NullPointerException - if mergeEntity or managedEntity is null
    
    IllegalArgumentException - if managedEntity is not the same as the previous managed entity associated with merge entity
    
    IllegalStateException - if internal cross-references are out of sync,
  - putAll
```
public void putAll(Map map)
```
    Copies all of the mappings from the specified Map to this MergeContext. The key and value for each entry in map is subject to the same restrictions as put(Object mergeEntity, Object managedEntity). This method assumes that the merge process is not yet operating on any merge entity
    
    Specified by:
    
    putAll in interface Map
    
    Parameters:
    
    map - keys and values must be non-null
    
    Throws:
    
    NullPointerException - if any key or value is null
    
    IllegalArgumentException - if a key in map was already in this MergeContext but associated value in map is different from the previous value in this MergeContext.
    
    IllegalStateException - if internal cross-references are out of sync,
  - remove
```
public Object remove(Object mergeEntity)
```
    The remove operation is not supported.
    
    Specified by:
    
    remove in interface Map
    
    Parameters:
    
    mergeEntity - the merge entity.
    
    Throws:
    
    UnsupportedOperationException - if called.
  - size
```
public int size()
```
    Returns the number of merge-to-managed entity cross-references in this MergeContext
    
    Specified by:
    
    size in interface Map
    
    Returns:
    
    the number of merge-to-managed entity cross-references in this MergeContext
  - values
```
public Collection values()
```
    Returns an unmodifiable Set view of managed entities contained in this MergeContext.
    
    Specified by:
    
    values in interface Map
    
    Returns:
    
    an unmodifiable Set view of managed entities contained in this MergeContext
    
    See Also:
    
    Collections.unmodifiableSet(java.util.Set)
  - isOperatedOn
```
public boolean isOperatedOn(Object mergeEntity)
```
    Returns true if the listener is performing the merge operation on the specified merge entity.
    
    Parameters:
    
    mergeEntity - the merge entity; must be non-null
    
    Returns:
    
    true if the listener is performing the merge operation on the specified merge entity; false, if there is no mapping for mergeEntity.
    
    Throws:
    
    NullPointerException - if mergeEntity is null
  - invertMap
```
public Map invertMap()
```
    Returns an unmodifiable map view of the managed-to-merge entity cross-references. The returned Map will contain a cross-reference from each managed entity to the most recently associated merge entity that was most recently put in the MergeContext.
    
    Returns:
    
    an unmodifiable map view of the managed-to-merge entity cross-references.
    
    See Also:
    
    Collections.unmodifiableMap(java.util.Map)

Class MergeContext

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.Map

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Map

Method Detail

clear

containsKey

containsValue

entrySet

get

isEmpty

keySet

put

putAll

remove

size

values

isOperatedOn

invertMap