JPA Interface

Expression<T>

Type Parameters:
<T> - the type of the expression
Super Interfaces:
Selection<T>, TupleElement<T>
Type for query expressions.
Since:
JPA 2.0
The JPA Query Expressions (JPQL / Criteria) article explains how to use Expression.

Public Methods

Expression<X> as(Class<X> type)
Perform a typecast upon the expression, returning a new expression object.
Unlike cast(), this method does not cause type conversion: the runtime type is not changed.

Warning: may result in a runtime failure.

Parameters:
type - intended type of the expression
Return:
new expression of the given type
See Also:
cast()
Since:
JPA 2.0
Expression<X> cast(Class<X> type)
Cast this expression to the specified type, returning a new expression object.
Unlike as(), this method does result in a runtime type conversion.

Providers are required to support casting scalar expressions to String, and String expressions to Integer, Long, Float, and Double. Support for typecasts between other basic types is not required.

Parameters:
type - a basic type
Return:
a scalar expression of the given basic type
Since:
JPA 3.2
Predicate equalTo(Expression<?> value)
Create a predicate to test whether the expression is equal to the argument.
Parameters:
value - expression to be tested against
Return:
predicate testing for equality
Since:
JPA 3.2
Predicate equalTo(Object value)
Create a predicate to test whether the expression is equal to the argument.
Parameters:
value - value to be tested against
Return:
predicate testing for equality
Since:
JPA 3.2
Predicate in(Collection<?> values)
Create a predicate to test whether the expression is a member of the collection.
Parameters:
values - collection of values to be tested against
Return:
predicate testing for membership
Since:
JPA 2.0
Predicate in(Expression<?>... values)
Create a predicate to test whether the expression is a member of the argument list.
Parameters:
values - expressions to be tested against
Return:
predicate testing for membership
Since:
JPA 2.0
Predicate in(Expression<Collection<?>> values)
Create a predicate to test whether the expression is a member of the collection.
Parameters:
values - expression corresponding to collection to be tested against
Return:
predicate testing for membership
Since:
JPA 2.0
Predicate in(Object... values)
Create a predicate to test whether the expression is a member of the argument list.
Parameters:
values - values to be tested against
Return:
predicate testing for membership
Since:
JPA 2.0
Predicate isNotNull()
Create a predicate to test whether the expression is not null.
Return:
predicate testing whether the expression is not null
Since:
JPA 2.0
Predicate isNull()
Create a predicate to test whether the expression is null.
Return:
predicate testing whether the expression is null
Since:
JPA 2.0
Predicate notEqualTo(Expression<?> value)
Create a predicate to test whether the expression is unequal to the argument.
Parameters:
value - expression to be tested against
Return:
predicate testing for inequality
Since:
JPA 3.2
Predicate notEqualTo(Object value)
Create a predicate to test whether the expression is unequal to the argument.
Parameters:
value - value to be tested against
Return:
predicate testing for inequality
Since:
JPA 3.2