## org.springframework.core
Class MethodParameter

    java.lang.Object
      org.springframework.core.MethodParameter

    public class MethodParameter

extends Object

Helper class that encapsulates the specification of a method parameter, i.e. a Method or Constructor plus a parameter index and a nested type index for a declared generic type. Useful as a specification object to pass along.

Used by `GenericCollectionTypeResolver`, `BeanWrapperImpl` and `AbstractBeanFactory`.

Note that this class does not depend on JDK 1.5 API artifacts, in order to remain compatible with JDK 1.4. Concrete generic type resolution via JDK 1.5 API happens in `GenericCollectionTypeResolver` only.

Since:
  2.0
Author:
  Juergen Hoeller, Rob Harrop
See Also:
  `GenericCollectionTypeResolver`

Constructor Summary
`MethodParameter(Constructor constructor, int parameterIndex)` Create a new MethodParameter for the given constructor, with nesting level 1.
`MethodParameter(Constructor constructor, int parameterIndex, int nestingLevel)` Create a new MethodParameter for the given constructor.
`MethodParameter(Method method, int parameterIndex)` Create a new MethodParameter for the given method, with nesting level 1.
`MethodParameter(Method method, int parameterIndex, int nestingLevel)` Create a new MethodParameter for the given method.
`MethodParameter(MethodParameter original)` Copy constructor, resulting in an independent MethodParameter object based on the same metadata and cache state that the original object was in.

Method Summary
`void` `decreaseNestingLevel()` Decrease this parameter's nesting level.
`static MethodParameter` `forMethodOrConstructor(Object methodOrConstructor, int parameterIndex)` Create a new MethodParameter for the given method or constructor.
`Constructor` `getConstructor()` Return the wrapped Constructor, if any.
`Method` `getMethod()` Return the wrapped Method, if any.
`int` `getNestingLevel()` Return the nesting level of the target type (typically 1; e.g. in case of a List of Lists, 1 would indicate the nested List, whereas 2 would indicate the element of the nested List).
`Object[]` `getParameterAnnotations()` Return the annotations associated with the method/constructor parameter.
`int` `getParameterIndex()` Return the index of the method/constructor parameter.
`String` `getParameterName()` Return the name of the method/constructor parameter.
`Class` `getParameterType()` Return the type of the method/constructor parameter.
`Integer` `getTypeIndexForCurrentLevel()` Return the type index for the current nesting level.
`Integer` `getTypeIndexForLevel(int nestingLevel)` Return the type index for the specified nesting level.
`void` `increaseNestingLevel()` Increase this parameter's nesting level.
`void` `initParameterNameDiscovery(ParameterNameDiscoverer parameterNameDiscoverer)` Initialize parameter name discovery for this method parameter.
`void` `setTypeIndexForCurrentLevel(int typeIndex)` Set the type index for the current nesting level.

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

Constructor Detail

### MethodParameter

    public MethodParameter(Method method,
                           int parameterIndex)

  Create a new MethodParameter for the given method, with nesting level 1.

  Parameters:
    `method` - the Method to specify a parameter for
    `parameterIndex` - the index of the parameter

### MethodParameter

    public MethodParameter(Method method,
                           int parameterIndex,
                           int nestingLevel)

  Create a new MethodParameter for the given method.

  Parameters:
    `method` - the Method to specify a parameter for
    `parameterIndex` - the index of the parameter (-1 for the method return type; 0 for the first method parameter, 1 for the second method parameter, etc)
    `nestingLevel` - the nesting level of the target type (typically 1; e.g. in case of a List of Lists, 1 would indicate the nested List, whereas 2 would indicate the element of the nested List)

### MethodParameter

    public MethodParameter(Constructor constructor,
                           int parameterIndex)

  Create a new MethodParameter for the given constructor, with nesting level 1.

  Parameters:
    `constructor` - the Constructor to specify a parameter for
    `parameterIndex` - the index of the parameter

### MethodParameter

    public MethodParameter(Constructor constructor,
                           int parameterIndex,
                           int nestingLevel)

  Create a new MethodParameter for the given constructor.

  Parameters:
    `constructor` - the Constructor to specify a parameter for
    `parameterIndex` - the index of the parameter
    `nestingLevel` - the nesting level of the target type (typically 1; e.g. in case of a List of Lists, 1 would indicate the nested List, whereas 2 would indicate the element of the nested List)

### MethodParameter

    public MethodParameter(MethodParameter original)

  Copy constructor, resulting in an independent MethodParameter object based on the same metadata and cache state that the original object was in.

  Parameters:
    `original` - the original MethodParameter object to copy from

Method Detail

### getMethod

    public Method getMethod()

  Return the wrapped Method, if any.

  Note: Either Method or Constructor is available.

  Returns:
    the Method, or `null` if none

### getConstructor

    public Constructor getConstructor()

  Return the wrapped Constructor, if any.

  Note: Either Method or Constructor is available.

  Returns:
    the Constructor, or `null` if none

### getParameterIndex

    public int getParameterIndex()

  Return the index of the method/constructor parameter.

  Returns:
    the parameter index (never negative)

### getParameterType

    public Class getParameterType()

  Return the type of the method/constructor parameter.

  Returns:
    the parameter type (never `null`)

### getParameterAnnotations

    public Object[] getParameterAnnotations()

  Return the annotations associated with the method/constructor parameter.

  Returns:
    the parameter annotations, or `null` if there is no annotation support (on JDK < 1.5). The return value is an Object array instead of an Annotation array simply for compatibility with older JDKs; feel free to cast it to `Annotation[]` on JDK 1.5 or higher.

### initParameterNameDiscovery

    public void initParameterNameDiscovery(ParameterNameDiscoverer parameterNameDiscoverer)

  Initialize parameter name discovery for this method parameter.

  This method does not actually try to retrieve the parameter name at this point; it just allows discovery to happen when the application calls `getParameterName()` (if ever).

### getParameterName

    public String getParameterName()

  Return the name of the method/constructor parameter.

  Returns:
    the parameter name (may be `null` if no parameter name metadata is contained in the class file or no `ParameterNameDiscoverer` has been set to begin with)

### increaseNestingLevel

    public void increaseNestingLevel()

  Increase this parameter's nesting level.

  See Also:
    `getNestingLevel()`

### decreaseNestingLevel

    public void decreaseNestingLevel()

  Decrease this parameter's nesting level.

  See Also:
    `getNestingLevel()`

### getNestingLevel

    public int getNestingLevel()

  Return the nesting level of the target type (typically 1; e.g. in case of a List of Lists, 1 would indicate the nested List, whereas 2 would indicate the element of the nested List).

### setTypeIndexForCurrentLevel

    public void setTypeIndexForCurrentLevel(int typeIndex)

  Set the type index for the current nesting level.

  Parameters:
    `typeIndex` - the corresponding type index (or `null` for the default type index)
  See Also:
    `getNestingLevel()`

### getTypeIndexForCurrentLevel

    public Integer getTypeIndexForCurrentLevel()

  Return the type index for the current nesting level.

  Returns:
    the corresponding type index, or `null` if none specified (indicating the default type index)
  See Also:
    `getNestingLevel()`

### getTypeIndexForLevel

    public Integer getTypeIndexForLevel(int nestingLevel)

  Return the type index for the specified nesting level.

  Parameters:
    `nestingLevel` - the nesting level to check
  Returns:
    the corresponding type index, or `null` if none specified (indicating the default type index)

### forMethodOrConstructor

    public static MethodParameter forMethodOrConstructor(Object methodOrConstructor,
                                                         int parameterIndex)

  Create a new MethodParameter for the given method or constructor.

  This is a convenience constructor for scenarios where a Method or Constructor reference is treated in a generic fashion.

  Parameters:
    `methodOrConstructor` - the Method or Constructor to specify a parameter for
    `parameterIndex` - the index of the parameter
  Returns:
    the corresponding MethodParameter instance

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