Package jakarta.el

## Class ValueExpression

- java.lang.Object
- - jakarta.el.Expression
  - - jakarta.el.ValueExpression

All Implemented Interfaces:
  `java.io.Serializable`

    public abstract class ValueExpression
    extends Expression

See Also:
  Serialized Form

### Constructor Summary

Constructors
`ValueExpression()`

### Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
`abstract java.lang.Class<?>` `getExpectedType()`
`abstract java.lang.Class<?>` `getType​(ELContext context)`
`abstract <T> T` `getValue​(ELContext context)`
`ValueReference` `getValueReference​(ELContext context)`
`abstract boolean` `isReadOnly​(ELContext context)`
`abstract void` `setValue​(ELContext context, java.lang.Object value)`

### Methods inherited from class jakarta.el.Expression

`equals, getExpressionString, hashCode, isLiteralText`

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

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

### Constructor Detail

#### ValueExpression

    public ValueExpression()

### Method Detail

#### getValue

    public abstract <T> T getValue​(ELContext context)

Type Parameters:
  `T` - The expected type for the result of evaluating this value expression
Parameters:
  `context` - The EL context for this evaluation
Returns:
  The result of evaluating this value expression
Throws:
  `java.lang.NullPointerException` - If the supplied context is `null`
  `PropertyNotFoundException` - If a property/variable resolution failed because no match was found or a match was found but was not readable
  `ELException` - Wraps any exception throw whilst resolving a property or variable

#### setValue

    public abstract void setValue​(ELContext context,
                                  java.lang.Object value)

Parameters:
  `context` - The EL context for this evaluation
  `value` - The value to set the property to which this value expression refers
Throws:
  `java.lang.NullPointerException` - If the supplied context is `null`
  `PropertyNotFoundException` - If a property/variable resolution failed because no match was found
  `PropertyNotWritableException` - If a property/variable resolution failed because a match was found but was not writable
  `ELException` - Wraps any exception throw whilst resolving a property or variable

#### isReadOnly

    public abstract boolean isReadOnly​(ELContext context)

Parameters:
  `context` - The EL context for this evaluation
Returns:
  `true` if this expression is read only otherwise `false`
Throws:
  `java.lang.NullPointerException` - If the supplied context is `null`
  `PropertyNotFoundException` - If a property/variable resolution failed because no match was found or a match was found but was not readable
  `ELException` - Wraps any exception throw whilst resolving a property or variable

#### getType

    public abstract java.lang.Class<?> getType​(ELContext context)

Parameters:
  `context` - The EL context for this evaluation
Returns:
  The type of the result of this value expression
Throws:
  `java.lang.NullPointerException` - If the supplied context is `null`
  `PropertyNotFoundException` - If a property/variable resolution failed because no match was found or a match was found but was not readable
  `ELException` - Wraps any exception throw whilst resolving a property or variable

#### getExpectedType

    public abstract java.lang.Class<?> getExpectedType()

#### getValueReference

    public ValueReference getValueReference​(ELContext context)

Parameters:
  `context` - The EL context for this evaluation
Returns:
  This default implementation always returns `null`
Since:
  EL 2.2