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Oracle Fusion Middleware Java API Reference for Oracle ADF Mobile 11g Release 2 (11.1.2.4.0) E27204-03 |
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java.lang.Object
javax.el.Expression
javax.el.MethodExpression
public abstract class MethodExpression
An Expression that refers to a method on an object. The ExpressionFactory.createMethodExpression(ELContext, String, Class, 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(ELContext)
and invoke(ELContext, 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(ELContext, Object, 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 PropertyNotFoundException 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.
ELResolver
, Expression
, ExpressionFactory
, Serialized FormConstructor Summary | |
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MethodExpression() |
Method Summary | |
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abstract MethodInfo |
getMethodInfo(ELContext context) Evaluates the expression relative to the provided context, and returns information about the actual referenced method. |
abstract java.lang.Object |
invoke(ELContext context, java.lang.Object[] params) If a String literal is specified as the expression, returns the String literal coerced to the expected return type of the method signature. |
boolean |
isParmetersProvided() Return whether this MethodExpression was created with parameters. |
Methods inherited from class javax.el.Expression |
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equals, getExpressionString, hashCode, isLiteralText |
Methods inherited from class java.lang.Object |
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getClass, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public MethodExpression()
Method Detail |
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public abstract MethodInfo getMethodInfo(ELContext context)
context
- The context of this evaluation.java.lang.NullPointerException
- if context is nullPropertyNotFoundException
- 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.public abstract java.lang.Object invoke(ELContext context, java.lang.Object[] params)
context
- The context of this evaluation.params
- The parameters to pass to the method, or null if no parameters.java.lang.NullPointerException
- if context is nullPropertyNotFoundException
- 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 a String literal is specified and expectedReturnType of the MethodExpression is void or if the coercion of the String literal to the expectedReturnType yields an error (see Section "1.16 Type Conversion").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 cause and pass it to the ELException constructor.public boolean isParmetersProvided()
This method must return true
if and only if parameters are specified in the EL, using the expr-a.expr-b(...) syntax.
true
if the MethodExpression was created with parameters, false
otherwise.
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Oracle Fusion Middleware Java API Reference for Oracle ADF Mobile 11g Release 2 (11.1.2.4.0) E27204-03 |
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