public class ConstantExpression extends Object implements Literal, Cloneable
However we do have a need for immutable literal expressions when defining our API for SLD, and any other standards based on Expression.
Modifier and Type | Field and Description |
---|---|
static ConstantExpression |
BLACK |
static ConstantExpression |
NULL |
static ConstantExpression |
ONE |
static ConstantExpression |
TWO |
static ConstantExpression |
UNNAMED |
static ConstantExpression |
ZERO |
NIL
Modifier | Constructor and Description |
---|---|
protected |
ConstantExpression(Object value) |
protected |
ConstantExpression(short type,
Object value) |
Modifier and Type | Method and Description |
---|---|
Object |
accept(ExpressionVisitor visitor,
Object extraData)
Accepts a visitor.
|
protected Object |
clone() |
static ConstantExpression |
color(Color color)
Encode provided color as a String
|
static ConstantExpression |
constant(double number) |
static ConstantExpression |
constant(int number) |
static ConstantExpression |
constant(Object value) |
boolean |
equals(Object obj) |
Object |
evaluate(Object object)
Evaluates the given expression based on the content of the given object.
|
<T> T |
evaluate(Object object,
Class<T> context)
Evaluates the given expressoin based on the content of the given object and the context type.
|
Object |
evaluate(SimpleFeature feature) |
Object |
getLiteral()
Deprecated.
use
getValue() |
short |
getType() |
Object |
getValue()
Returns the constant value held by this object.
|
Object |
getValue(SimpleFeature feature)
Deprecated.
use
#evaluate(Feature) |
int |
hashCode() |
void |
setLiteral(Object literal)
Deprecated.
use
setValue(Object) |
void |
setValue(Object constant) |
String |
toString() |
public static final ConstantExpression NULL
public static final ConstantExpression BLACK
public static final ConstantExpression ZERO
public static final ConstantExpression ONE
public static final ConstantExpression TWO
public static final ConstantExpression UNNAMED
protected ConstantExpression(Object value)
protected ConstantExpression(short type, Object value)
public final void setLiteral(Object literal) throws IllegalFilterException
setValue(Object)
IllegalFilterException
public final Object getValue(SimpleFeature feature)
#evaluate(Feature)
public Object evaluate(SimpleFeature feature)
public Object evaluate(Object object)
Expression
evaluate
in interface Expression
public <T> T evaluate(Object object, Class<T> context)
Expression
The context
parameter is used to control the type of the result of the expression.
A particular expression may not be able to evaluate to an instance of context
.
Therefore to be safe calling code should do a null check on the return value of this method,
and call Expression.evaluate(Object)
if neccessary. Example:
Object input = ...; String result = expression.evaluate( input, String.class ); if ( result == null ) { result = expression.evalute( input ).toString(); } ...
Implementations that can not return a result as an instance of context
should
return null
.
evaluate
in interface Expression
T
- The type of the returned object.object
- The object to evaluate the expression against.context
- The type of the resulting value of the expression.context
.public Object getValue()
Literal
public void setValue(Object constant)
public short getType()
public final Object getLiteral()
getValue()
public Object accept(ExpressionVisitor visitor, Object extraData)
Expression
return visitor.visit(this, extraData);
accept
in interface Expression
protected Object clone() throws CloneNotSupportedException
clone
in class Object
CloneNotSupportedException
public static ConstantExpression color(Color color)
public static ConstantExpression constant(double number)
public static ConstantExpression constant(int number)
public static ConstantExpression constant(Object value)
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