Class ClosureUtils
- 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
- Since:
- Commons Collections 3.0
- Version:
- $Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
- Author:
- Stephen Colebourne, Matt Benson
-
-
Constructor Summary
Constructors Constructor Description ClosureUtils()
This class is not normally instantiated.
-
Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static Closure
asClosure(Transformer transformer)
Creates a Closure that calls a Transformer each time it is called.static Closure
chainedClosure(Collection closures)
Create a new Closure that calls each closure in turn, passing the result into the next closure.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
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 closurecount
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.
-
-
-
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 closurecount
times.A null closure or zero count returns the
NOPClosure
.- Parameters:
count
- the number of times to loopclosure
- 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 nullclosure
- 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 nullpredicate
- 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 methodparamTypes
- the parameter typesargs
- the arguments- Returns:
- the
invoker
closure - Throws:
IllegalArgumentException
- if the method name is nullIllegalArgumentException
- 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 closureclosure2
- 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 nullIllegalArgumentException
- 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 nullIllegalArgumentException
- if the closures collection is emptyIllegalArgumentException
- 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 predicatetrueClosure
- the closure called if the predicate is true- Returns:
- the
if
closure - Throws:
IllegalArgumentException
- if the predicate is nullIllegalArgumentException
- 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 ontrueClosure
- the closure called if the predicate is truefalseClosure
- the closure called if the predicate is false- Returns:
- the
switch
closure - Throws:
IllegalArgumentException
- if the predicate is nullIllegalArgumentException
- 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 nullclosures
- an array of closures to call, not null- Returns:
- the
switch
closure - Throws:
IllegalArgumentException
- if the either array is nullIllegalArgumentException
- if any element in the arrays is nullIllegalArgumentException
- 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 nullclosures
- an array of closures to call, not nulldefaultClosure
- the default to call if no predicate matches- Returns:
- the
switch
closure - Throws:
IllegalArgumentException
- if the either array is nullIllegalArgumentException
- if any element in the arrays is nullIllegalArgumentException
- 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 nullIllegalArgumentException
- if the map is emptyIllegalArgumentException
- if any closure in the map is nullClassCastException
- 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 nullIllegalArgumentException
- if the map is emptyIllegalArgumentException
- if any closure in the map is null- See Also:
SwitchClosure
-
-