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java.lang.Objectjava.lang.Enum<LockModeType>
javax.persistence.LockModeType
public enum LockModeType
Lock modes that can be specified by means of the EntityManager.lock() method. The semantics of requesting locks of type LockModeType.READ and LockModeType.WRITE are t he following. If transaction T1 calls lock(entity, LockModeType.READ) on a versioned object, the entity manager must ensure that neither of the following phenomena can occur: * P1 (Dirty read): Transaction T1 modifies a row. Another transaction T2 then reads that row and obtains the modified value, before T1 has committed or rolled back. Transaction T2 eventually commits successfully; it does not matter whether T1 commits or rolls back and whether it does so before or after T2 commits. * P2 (Non-repeatable read): Transaction T1 reads a row. Another transaction T2 then modifies or deletes that row, before T1 has committed. Both transactions eventually commit successfully. Lock modes must always prevent the phenomena P1 and P2. In addition, calling lock(entity, LockModeType.WRITE) on a versioned object, will also force an update (increment) to the entity's version column. The persistence implementation is not required to support calling EntityManager.lock() on a non-versioned object. When it cannot support a such lock call, it must throw the PersistenceException.
Enum Constant Summary | |
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READ
Read lock |
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WRITE
Write lock |
Method Summary | |
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static LockModeType |
valueOf(String name)
Returns the enum constant of this type with the specified name. |
static LockModeType[] |
values()
Returns an array containing the constants of this enum type, in the order they're declared. |
Methods inherited from class java.lang.Enum |
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clone, compareTo, equals, getDeclaringClass, hashCode, name, ordinal, toString, valueOf |
Methods inherited from class java.lang.Object |
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finalize, getClass, notify, notifyAll, wait, wait, wait |
Enum Constant Detail |
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public static final LockModeType READ
public static final LockModeType WRITE
Method Detail |
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public static final LockModeType[] values()
for(LockModeType c : LockModeType.values()) System.out.println(c);
public static LockModeType valueOf(String name)
name
- the name of the enum constant to be returned.
IllegalArgumentException
- if this enum type has no constant
with the specified name
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