# Class FunctionMapper

java.lang.Object
jakarta.el.FunctionMapper

public abstract class FunctionMapper extends Object
Abstract base class for mapping EL function names to Java `Method` objects. During expression evaluation, the EL implementation uses the FunctionMapper to resolve function references of the form `prefix:functionName` to the corresponding static Java methods. Implementations maintain a registry of function prefixes and names mapped to their underlying methods.

Since:
  EL 2.1

## Constructor Summary

Constructors
Constructor
Description
`FunctionMapper()`
Constructs a FunctionMapper.

## Method Summary

Modifier and Type
Method
Description
`void`
`mapFunction(String prefix, String localName, Method method)`
Map a method to a function name.
`abstract Method`
`resolveFunction(String prefix, String localName)`
Resolves a function reference to its corresponding static `Method`.

### Methods inherited from class Object

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

## Constructor Details

### FunctionMapper

public FunctionMapper()
Constructs a FunctionMapper. Subclasses should invoke this constructor to initialize the base mapper state.

## Method Details

### resolveFunction

public abstract Method resolveFunction(String prefix, String localName)
Resolves a function reference to its corresponding static `Method`.

Parameters:
  `prefix` - the namespace prefix of the function
  `localName` - the local name of the function
Returns:
  the `Method` object for the resolved function, or `null` if not found

### mapFunction

public void mapFunction(String prefix, String localName, Method method)
Map a method to a function name.

Parameters:
  `prefix` - Function prefix
  `localName` - Function name
  `method` - Method
Since:
  EL 3.0