ClosureUtils (Apache Commons Collections 3.2.2 API)

java.lang.Object
- org.apache.commons.collections.ClosureUtils

```
public class ClosureUtils
extends Object
```
ClosureUtils provides reference implementations and utilities for the Closure functor interface. The supplied closures are:
- Invoker - invokes a method on the input object
- For - repeatedly calls a closure for a fixed number of times
- While - repeatedly calls a closure while a predicate is true
- DoWhile - repeatedly calls a closure while a predicate is true
- Chained - chains two or more closures together
- Switch - calls one closure based on one or more predicates
- SwitchMap - calls one closure looked up from a Map
- Transformer - wraps a Transformer as a Closure
- NOP - does nothing
- Exception - always throws an exception
All the supplied closures are Serializable.
Since:

Commons Collections 3.0

Version:

$Revision: 972404 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $

Author:

Stephen Colebourne, Matt Benson

Constructor Summary

Constructors
Constructor and Description

ClosureUtils()
This class is not normally instantiated.

Constructors
Constructor and Description
`ClosureUtils()` This class is not normally instantiated.

Method Summary

Methods
Modifier and Type	Method and Description
`static Closure`	`asClosure(Transformer transformer)` Creates a Closure that calls a Transformer each time it is called.
`static Closure`	`chainedClosure(Closure[] closures)` Create a new Closure that calls each closure in turn, passing the result into the next closure.
`static Closure`	`chainedClosure(Closure closure1, Closure closure2)` Create a new Closure that calls two Closures, passing the result of the first into the second.
`static Closure`	`chainedClosure(Collection closures)` Create a new Closure that calls each closure in turn, passing the result into the next closure.
`static Closure`	`doWhileClosure(Closure closure, Predicate predicate)` Creates a Closure that will call the closure once and then repeatedly until the predicate returns false.
`static Closure`	`exceptionClosure()` Gets a Closure that always throws an exception.
`static Closure`	`forClosure(int count, Closure closure)` Creates a Closure that will call the closure `count` times.
`static Closure`	`ifClosure(Predicate predicate, Closure trueClosure)` Create a new Closure that calls another closure based on the result of the specified predicate.
`static Closure`	`ifClosure(Predicate predicate, Closure trueClosure, Closure falseClosure)` Create a new Closure that calls one of two closures depending on the specified predicate.
`static Closure`	`invokerClosure(String methodName)` Creates a Closure that will invoke a specific method on the closure's input object by reflection.
`static Closure`	`invokerClosure(String methodName, Class[] paramTypes, Object[] args)` Creates a Closure that will invoke a specific method on the closure's input object by reflection.
`static Closure`	`nopClosure()` Gets a Closure that will do nothing.
`static Closure`	`switchClosure(Map predicatesAndClosures)` Create a new Closure that calls one of the closures depending on the predicates.
`static Closure`	`switchClosure(Predicate[] predicates, Closure[] closures)` Create a new Closure that calls one of the closures depending on the predicates.
`static Closure`	`switchClosure(Predicate[] predicates, Closure[] closures, Closure defaultClosure)` Create a new Closure that calls one of the closures depending on the predicates.
`static Closure`	`switchMapClosure(Map objectsAndClosures)` Create a new Closure that uses the input object as a key to find the closure to call.
`static Closure`	`whileClosure(Predicate predicate, Closure closure)` Creates a Closure that will call the closure repeatedly until the predicate returns false.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - ClosureUtils
```
public ClosureUtils()
```
    This class is not normally instantiated.
- Method Detail
  - exceptionClosure
```
public static Closure exceptionClosure()
```
    Gets a Closure that always throws an exception. This could be useful during testing as a placeholder.
    
    Returns:
    the closure
    See Also:
    ExceptionClosure
  - nopClosure
```
public static Closure nopClosure()
```
    Gets a Closure that will do nothing. This could be useful during testing as a placeholder.
    
    Returns:
    the closure
    See Also:
    NOPClosure
  - asClosure
```
public static Closure asClosure(Transformer transformer)
```
    Creates a Closure that calls a Transformer each time it is called. The transformer will be called using the closure's input object. The transformer's result will be ignored.
    
    Parameters:
    transformer - the transformer to run each time in the closure, null means nop
    
    Returns:
    the closure
    See Also:
    TransformerClosure
  - forClosure
```
public static Closure forClosure(int count,
                 Closure closure)
```
    Creates a Closure that will call the closure count times.
    A null closure or zero count returns the NOPClosure.
    
    Parameters:
    count - the number of times to loop
    closure - the closure to call repeatedly
    
    Returns:
    the for closure
    See Also:
    ForClosure
  - whileClosure
```
public static Closure whileClosure(Predicate predicate,
                   Closure closure)
```
    Creates a Closure that will call the closure repeatedly until the predicate returns false.
    
    Parameters:
    predicate - the predicate to use as an end of loop test, not null
    closure - the closure to call repeatedly, not null
    
    Returns:
    the while closure
    
    Throws:
    
    IllegalArgumentException - if either argument is null
    See Also:
    WhileClosure
  - doWhileClosure
```
public static Closure doWhileClosure(Closure closure,
                     Predicate predicate)
```
    Creates a Closure that will call the closure once and then repeatedly until the predicate returns false.
    
    Parameters:
    closure - the closure to call repeatedly, not null
    predicate - the predicate to use as an end of loop test, not null
    
    Returns:
    the do-while closure
    
    Throws:
    
    IllegalArgumentException - if either argument is null
    See Also:
    WhileClosure
  - invokerClosure
```
public static Closure invokerClosure(String methodName)
```
    Creates a Closure that will invoke a specific method on the closure's input object by reflection.
    
    Parameters:
    methodName - the name of the method
    
    Returns:
    the invoker closure
    
    Throws:
    
    IllegalArgumentException - if the method name is null
    See Also:
    InvokerTransformer, TransformerClosure
  - invokerClosure
```
public static Closure invokerClosure(String methodName,
                     Class[] paramTypes,
                     Object[] args)
```
    Creates a Closure that will invoke a specific method on the closure's input object by reflection.
    
    Parameters:
    methodName - the name of the method
    paramTypes - the parameter types
    args - the arguments
    
    Returns:
    the invoker closure
    
    Throws:
    
    IllegalArgumentException - if the method name is null
    
    IllegalArgumentException - if the paramTypes and args don't match
    See Also:
    InvokerTransformer, TransformerClosure
  - chainedClosure
```
public static Closure chainedClosure(Closure closure1,
                     Closure closure2)
```
    Create a new Closure that calls two Closures, passing the result of the first into the second.
    
    Parameters:
    closure1 - the first closure
    closure2 - the second closure
    
    Returns:
    the chained closure
    
    Throws:
    
    IllegalArgumentException - if either closure is null
    See Also:
    ChainedClosure
  - chainedClosure
```
public static Closure chainedClosure(Closure[] closures)
```
    Create a new Closure that calls each closure in turn, passing the result into the next closure.
    
    Parameters:
    closures - an array of closures to chain
    
    Returns:
    the chained closure
    
    Throws:
    
    IllegalArgumentException - if the closures array is null
    
    IllegalArgumentException - if any closure in the array is null
    See Also:
    ChainedClosure
  - chainedClosure
```
public static Closure chainedClosure(Collection closures)
```
    Create a new Closure that calls each closure in turn, passing the result into the next closure. The ordering is that of the iterator() method on the collection.
    
    Parameters:
    closures - a collection of closures to chain
    
    Returns:
    the chained closure
    
    Throws:
    
    IllegalArgumentException - if the closures collection is null
    
    IllegalArgumentException - if the closures collection is empty
    
    IllegalArgumentException - if any closure in the collection is null
    See Also:
    ChainedClosure
  - ifClosure
```
public static Closure ifClosure(Predicate predicate,
                Closure trueClosure)
```
    Create a new Closure that calls another closure based on the result of the specified predicate.
    
    Parameters:
    predicate - the validating predicate
    trueClosure - the closure called if the predicate is true
    
    Returns:
    the if closure
    
    Throws:
    
    IllegalArgumentException - if the predicate is null
    
    IllegalArgumentException - if the closure is null
    Since:
    
    Commons Collections 3.2
    
    See Also:
    IfClosure
  - ifClosure
```
public static Closure ifClosure(Predicate predicate,
                Closure trueClosure,
                Closure falseClosure)
```
    Create a new Closure that calls one of two closures depending on the specified predicate.
    
    Parameters:
    predicate - the predicate to switch on
    trueClosure - the closure called if the predicate is true
    falseClosure - the closure called if the predicate is false
    
    Returns:
    the switch closure
    
    Throws:
    
    IllegalArgumentException - if the predicate is null
    
    IllegalArgumentException - if either closure is null
    See Also:
    IfClosure
  - switchClosure
```
public static Closure switchClosure(Predicate[] predicates,
                    Closure[] closures)
```
    Create a new Closure that calls one of the closures depending on the predicates.
    The closure at array location 0 is called if the predicate at array location 0 returned true. Each predicate is evaluated until one returns true.
    
    Parameters:
    predicates - an array of predicates to check, not null
    closures - an array of closures to call, not null
    
    Returns:
    the switch closure
    
    Throws:
    
    IllegalArgumentException - if the either array is null
    
    IllegalArgumentException - if any element in the arrays is null
    
    IllegalArgumentException - if the arrays are different sizes
    See Also:
    SwitchClosure
  - switchClosure
```
public static Closure switchClosure(Predicate[] predicates,
                    Closure[] closures,
                    Closure defaultClosure)
```
    Create a new Closure that calls one of the closures depending on the predicates.
    The closure at array location 0 is called if the predicate at array location 0 returned true. Each predicate is evaluated until one returns true. If no predicates evaluate to true, the default closure is called.
    
    Parameters:
    predicates - an array of predicates to check, not null
    closures - an array of closures to call, not null
    defaultClosure - the default to call if no predicate matches
    
    Returns:
    the switch closure
    
    Throws:
    
    IllegalArgumentException - if the either array is null
    
    IllegalArgumentException - if any element in the arrays is null
    
    IllegalArgumentException - if the arrays are different sizes
    See Also:
    SwitchClosure
  - switchClosure
```
public static Closure switchClosure(Map predicatesAndClosures)
```
    Create a new Closure that calls one of the closures depending on the predicates.
    The Map consists of Predicate keys and Closure values. A closure is called if its matching predicate returns true. Each predicate is evaluated until one returns true. If no predicates evaluate to true, the default closure is called. The default closure is set in the map with a null key. The ordering is that of the iterator() method on the entryset collection of the map.
    
    Parameters:
    predicatesAndClosures - a map of predicates to closures
    
    Returns:
    the switch closure
    
    Throws:
    
    IllegalArgumentException - if the map is null
    
    IllegalArgumentException - if the map is empty
    
    IllegalArgumentException - if any closure in the map is null
    
    ClassCastException - if the map elements are of the wrong type
    See Also:
    SwitchClosure
  - switchMapClosure
```
public static Closure switchMapClosure(Map objectsAndClosures)
```
    Create a new Closure that uses the input object as a key to find the closure to call.
    The Map consists of object keys and Closure values. A closure is called if the input object equals the key. If there is no match, the default closure is called. The default closure is set in the map using a null key.
    
    Parameters:
    objectsAndClosures - a map of objects to closures
    
    Returns:
    the closure
    
    Throws:
    
    IllegalArgumentException - if the map is null
    
    IllegalArgumentException - if the map is empty
    
    IllegalArgumentException - if any closure in the map is null
    See Also:
    SwitchClosure

Class ClosureUtils

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

ClosureUtils

Method Detail

exceptionClosure

nopClosure

asClosure

forClosure

whileClosure

doWhileClosure

invokerClosure

invokerClosure

chainedClosure

chainedClosure

chainedClosure

ifClosure

ifClosure

switchClosure

switchClosure

switchClosure

switchMapClosure