Class MethodExpressionImpl
- All Implemented Interfaces:
- Externalizable,- Serializable
Expression that refers to a method on an object.
 
 The ExpressionFactory.createMethodExpression(jakarta.el.ELContext, java.lang.String, java.lang.Class<?>, java.lang.Class<?>[]) method
 can be used to parse an expression string and return a concrete instance
 of MethodExpression that encapsulates the parsed expression.
 The FunctionMapper is used at parse time, not evaluation time,
 so one is not needed to evaluate an expression using this class.
 However, the ELContext is needed at evaluation time.
The getMethodInfo(jakarta.el.ELContext) and invoke(jakarta.el.ELContext, java.lang.Object[]) methods will evaluate the
 expression each time they are called. The ELResolver in the
 ELContext is used to resolve the top-level variables and to
 determine the behavior of the . and []
 operators. For any of the two methods, the
 ELResolver.getValue(jakarta.el.ELContext, java.lang.Object, java.lang.Object) method is used to resolve all properties
 up to but excluding the last one. This provides the base object
 on which the method appears. If the base object is null, a
 NullPointerException must be thrown. At the last resolution,
 the final property is then coerced to a String,
 which provides the name of the method to be found. A method matching the
 name and expected parameters provided at parse time is found and it is
 either queried or invoked (depending on the method called on this
 MethodExpression).
See the notes about comparison, serialization and immutability in
 the Expression javadocs.
- Author:
- Jacob Hookom [jacob@hookom.net]
- See Also:
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Constructor SummaryConstructorsConstructorDescriptionMethodExpressionImpl(String expr, org.apache.el.parser.Node node, FunctionMapper fnMapper, VariableMapper varMapper, Class<?> expectedType, Class<?>[] paramTypes) 
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Method SummaryModifier and TypeMethodDescriptionbooleanDetermines whether the specified object is equal to thisExpression.Returns the original String used to create thisExpression, unmodified.getMethodInfo(ELContext context) Evaluates the expression relative to the provided context, and returns information about the actual referenced method.getMethodReference(ELContext context) Obtain theMethodReferencefor the method to which this method expression resolves.inthashCode()Returns the hash code for thisExpression.Evaluates the expression relative to the provided context, invokes the method that was found using the supplied parameters, and returns the result of the method invocation.booleanbooleanvoidvoid
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Constructor Details- 
MethodExpressionImplpublic MethodExpressionImpl()
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MethodExpressionImplpublic MethodExpressionImpl(String expr, org.apache.el.parser.Node node, FunctionMapper fnMapper, VariableMapper varMapper, Class<?> expectedType, Class<?>[] paramTypes) 
 
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Method Details- 
equalsDetermines whether the specified object is equal to thisExpression.The result is trueif and only if the argument is notnull, is anExpressionobject that is the of the same type (ValueExpressionorMethodExpression), and has an identical parsed representation.Note that two expressions can be equal if their expression Strings are different. For example, ${fn1:foo()}and${fn2:foo()}are equal if their correspondingFunctionMappers mappedfn1:fooandfn2:footo the same method.- Specified by:
- equalsin class- Expression
- Parameters:
- obj- the- Objectto test for equality.
- Returns:
- trueif- objequals this- Expression;- falseotherwise.
- See Also:
 
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getExpressionStringReturns the original String used to create thisExpression, unmodified.This is used for debugging purposes but also for the purposes of comparison (e.g. to ensure the expression in a configuration file has not changed). This method does not provide sufficient information to re-create an expression. Two different expressions can have exactly the same expression string but different function mappings. Serialization should be used to save and restore the state of an Expression.- Specified by:
- getExpressionStringin class- Expression
- Returns:
- The original expression String.
- See Also:
 
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getMethodInfopublic MethodInfo getMethodInfo(ELContext context) throws PropertyNotFoundException, MethodNotFoundException, ELException Evaluates the expression relative to the provided context, and returns information about the actual referenced method.- Specified by:
- getMethodInfoin class- MethodExpression
- Parameters:
- context- The context of this evaluation
- Returns:
- an instance of MethodInfocontaining information about the method the expression evaluated to.
- Throws:
- NullPointerException- if context is- nullor the base object is- nullon the last resolution.
- PropertyNotFoundException- if one of the property resolutions failed because a specified variable or property does not exist or is not readable.
- MethodNotFoundException- if no suitable method can be found.
- ELException- if an exception was thrown while performing property or variable resolution. The thrown exception must be included as the cause property of this exception, if available.
- See Also:
 
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hashCodepublic int hashCode()Returns the hash code for thisExpression.See the note in the equals(java.lang.Object)method on how two expressions can be equal if their expression Strings are different. Recall that if two objects are equal according to theequals(Object)method, then calling thehashCodemethod on each of the two objects must produce the same integer result. Implementations must take special note and implementhashCodecorrectly.- Specified by:
- hashCodein class- Expression
- Returns:
- The hash code for this Expression.
- See Also:
 
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invokepublic Object invoke(ELContext context, Object[] params) throws PropertyNotFoundException, MethodNotFoundException, ELException Evaluates the expression relative to the provided context, invokes the method that was found using the supplied parameters, and returns the result of the method invocation.- Specified by:
- invokein class- MethodExpression
- Parameters:
- context- The context of this evaluation.
- params- The parameters to pass to the method, or- nullif no parameters.
- Returns:
- the result of the method invocation (nullif the method has avoidreturn type).
- Throws:
- NullPointerException- if context is- nullor the base object is- nullon the last resolution.
- PropertyNotFoundException- if one of the property resolutions failed because a specified variable or property does not exist or is not readable.
- MethodNotFoundException- if no suitable method can be found.
- ELException- if an exception was thrown while performing property or variable resolution. The thrown exception must be included as the cause property of this exception, if available. If the exception thrown is an- InvocationTargetException, extract its- causeand pass it to the- ELExceptionconstructor.
- See Also:
 
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readExternal- Specified by:
- readExternalin interface- Externalizable
- Throws:
- IOException
- ClassNotFoundException
 
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writeExternal- Specified by:
- writeExternalin interface- Externalizable
- Throws:
- IOException
 
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isLiteralTextpublic boolean isLiteralText()- Specified by:
- isLiteralTextin class- Expression
 
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isParametersProvidedpublic boolean isParametersProvided()- Overrides:
- isParametersProvidedin class- MethodExpression
- Returns:
- This default implementation always returns false
- Since:
- EL 3.0
 
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getMethodReferenceDescription copied from class:jakarta.el.MethodExpressionObtain theMethodReferencefor the method to which this method expression resolves.- Overrides:
- getMethodReferencein class- MethodExpression
- Parameters:
- context- The EL context for this evaluation
- Returns:
- This default implementation always returns null
 
 
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