# Class Field

java.lang.Object
java.lang.reflect.AccessibleObject
java.lang.reflect.Field

All Implemented Interfaces:
  `AnnotatedElement, Member`

public final class Field extends AccessibleObject implements Member
A `Field` provides information about, and dynamic access to, a single field of a class or an interface. The reflected field may be a class (static) field or an instance field.

A `Field` permits widening conversions to occur during a get or set access operation, but throws an `IllegalArgumentException` if a narrowing conversion would occur.

Since:
  1.1
See Also:
  - `Member`
  - `Class`
  - `Class.getFields()`
  - `Class.getField(String)`
  - `Class.getDeclaredFields()`
  - `Class.getDeclaredField(String)`

- ## Field Summary

  ### Fields declared in interface Member

  `DECLARED, PUBLIC`
  Modifier and Type
  Field
  Description
  `static final int`
  `DECLARED`
  Identifies the set of declared members of a class or interface.
  `static final int`
  `PUBLIC`
  Identifies the set of all public members of a class or interface, including inherited members.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `Set<AccessFlag>`
  `accessFlags()`
  Returns an unmodifiable set of the access flags for this field, possibly empty.
  `boolean`
  `equals(Object obj)`
  Compares this `Field` against the specified object.
  `Object`
  `get(Object obj)`
  Returns the value of the field represented by this `Field`, on the specified object.
  `AnnotatedType`
  `getAnnotatedType()`
  Returns an AnnotatedType object that represents the use of a type to specify the declared type of the field represented by this Field.
  `<T extends Annotation>
  T`
  `getAnnotation(Class<T> annotationClass)`
  Returns this element's annotation for the specified type if such an annotation is present, else null.
  `<T extends Annotation>
  T[]`
  `getAnnotationsByType(Class<T> annotationClass)`
  Returns annotations that are associated with this element.
  `boolean`
  `getBoolean(Object obj)`
  Gets the value of a static or instance `boolean` field.
  `byte`
  `getByte(Object obj)`
  Gets the value of a static or instance `byte` field.
  `char`
  `getChar(Object obj)`
  Gets the value of a static or instance field of type `char` or of another primitive type convertible to type `char` via a widening conversion.
  `Class<?>`
  `getDeclaringClass()`
  Returns the `Class` object representing the class or interface that declares the field represented by this `Field` object.
  `double`
  `getDouble(Object obj)`
  Gets the value of a static or instance field of type `double` or of another primitive type convertible to type `double` via a widening conversion.
  `float`
  `getFloat(Object obj)`
  Gets the value of a static or instance field of type `float` or of another primitive type convertible to type `float` via a widening conversion.
  `Type`
  `getGenericType()`
  Returns a `Type` object that represents the declared type for the field represented by this `Field` object.
  `int`
  `getInt(Object obj)`
  Gets the value of a static or instance field of type `int` or of another primitive type convertible to type `int` via a widening conversion.
  `long`
  `getLong(Object obj)`
  Gets the value of a static or instance field of type `long` or of another primitive type convertible to type `long` via a widening conversion.
  `int`
  `getModifiers()`
  Returns the Java language modifiers for the field represented by this `Field` object, as an integer.
  `String`
  `getName()`
  Returns the name of the field represented by this `Field` object.
  `short`
  `getShort(Object obj)`
  Gets the value of a static or instance field of type `short` or of another primitive type convertible to type `short` via a widening conversion.
  `Class<?>`
  `getType()`
  Returns a `Class` object that identifies the declared type for the field represented by this `Field` object.
  `int`
  `hashCode()`
  Returns a hashcode for this `Field`.
  `boolean`
  `isEnumConstant()`
  Returns `true` if this field represents an element of an enumerated class; returns `false` otherwise.
  `boolean`
  `isSynthetic()`
  Returns `true` if this field is a synthetic field; returns `false` otherwise.
  `void`
  `set(Object obj, Object value)`
  Sets the field represented by this `Field` object on the specified object argument to the specified new value.
  `void`
  `setAccessible(boolean flag)`
  Set the `accessible` flag for this reflected object to the indicated boolean value.
  `void`
  `setBoolean(Object obj, boolean z)`
  Sets the value of a field as a `boolean` on the specified object.
  `void`
  `setByte(Object obj, byte b)`
  Sets the value of a field as a `byte` on the specified object.
  `void`
  `setChar(Object obj, char c)`
  Sets the value of a field as a `char` on the specified object.
  `void`
  `setDouble(Object obj, double d)`
  Sets the value of a field as a `double` on the specified object.
  `void`
  `setFloat(Object obj, float f)`
  Sets the value of a field as a `float` on the specified object.
  `void`
  `setInt(Object obj, int i)`
  Sets the value of a field as an `int` on the specified object.
  `void`
  `setLong(Object obj, long l)`
  Sets the value of a field as a `long` on the specified object.
  `void`
  `setShort(Object obj, short s)`
  Sets the value of a field as a `short` on the specified object.
  `String`
  `toGenericString()`
  Returns a string describing this `Field`, including its generic type.
  `String`
  `toString()`
  Returns a string describing this `Field`.

  ### Methods declared in class AccessibleObject

  `canAccess, getAnnotations, getDeclaredAnnotation, getDeclaredAnnotations, getDeclaredAnnotationsByType, isAccessible, isAnnotationPresent, setAccessible, trySetAccessible`
  Modifier and Type
  Method
  Description
  `final boolean`
  `canAccess(Object obj)`
  Test if the caller can access this reflected object.
  `Annotation[]`
  `getAnnotations()`
  Returns annotations that are present on this element.
  `<T extends Annotation>
  T`
  `getDeclaredAnnotation(Class<T> annotationClass)`
  Returns this element's annotation for the specified type if such an annotation is directly present, else null.
  `Annotation[]`
  `getDeclaredAnnotations()`
  Returns annotations that are directly present on this element.
  `<T extends Annotation>
  T[]`
  `getDeclaredAnnotationsByType(Class<T> annotationClass)`
  Returns this element's annotation(s) for the specified type if such annotations are either directly present or indirectly present.
  `boolean`
  `isAccessible()`
  Deprecated.
  This method is deprecated because its name hints that it checks if the reflected object is accessible when it actually indicates if the checks for Java language access control are suppressed.
  `boolean`
  `isAnnotationPresent(Class<? extends Annotation> annotationClass)`
  Returns true if an annotation for the specified type is present on this element, else false.
  `static void`
  `setAccessible(AccessibleObject[] array, boolean flag)`
  Convenience method to set the `accessible` flag for an array of reflected objects.
  `final boolean`
  `trySetAccessible()`
  Set the `accessible` flag for this reflected object to `true` if possible.

  ### Methods declared in class Object

  `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`
  Modifier and Type
  Method
  Description
  `protected Object`
  `clone()`
  Creates and returns a copy of this object.
  `protected void`
  `finalize()`
  Deprecated, for removal: This API element is subject to removal in a future version.
  Finalization is deprecated and subject to removal in a future release.
  `final Class<?>`
  `getClass()`
  Returns the runtime class of this `Object`.
  `final void`
  `notify()`
  Wakes up a single thread that is waiting on this object's monitor.
  `final void`
  `notifyAll()`
  Wakes up all threads that are waiting on this object's monitor.
  `final void`
  `wait()`
  Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
  `final void`
  `wait(long timeoutMillis)`
  Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
  `final void`
  `wait(long timeoutMillis, int nanos)`
  Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

- ## Method Details

  - ### setAccessible

    public void setAccessible(boolean flag)
    Set the `accessible` flag for this reflected object to the indicated boolean value. A value of `true` indicates that the reflected object should suppress checks for Java language access control when it is used. A value of `false` indicates that the reflected object should enforce checks for Java language access control when it is used, with the variation noted in the class description.

    This method may be used by a caller in class `C` to enable access to a `member` of `declaring class` `D` if any of the following hold:

    - `C` and `D` are in the same module.
    - The member is `public` and `D` is `public` in a package that the module containing `D` `exports` to at least the module containing `C`.
    - The member is `protected` `static`, `D` is `public` in a package that the module containing `D` exports to at least the module containing `C`, and `C` is a subclass of `D`.
    - `D` is in a package that the module containing `D` `opens` to at least the module containing `C`. All packages in unnamed and open modules are open to all modules and so this method always succeeds when `D` is in an unnamed or open module.

    This method may be used by JNI code with no caller class on the stack to enable access to a `member` of `declaring class` `D` if and only if:

    - The member is `public` and `D` is `public` in a package that the module containing `D` `exports` unconditionally.

    This method cannot be used to enable access to private members, members with default (package) access, protected instance members, or protected constructors when the declaring class is in a different module to the caller and the package containing the declaring class is not open to the caller's module.

    If this reflected object represents a non-final field, and this method is used to enable access, then both read and write access to the field are enabled.

    If this reflected object represents a non-modifiable final field then enabling access only enables read access. Any attempt to set the field value throws an `IllegalAccessException`. The following fields are non-modifiable:

    - static final fields declared in any class or interface
    - final fields declared in a record
    - final fields declared in a hidden class

    If this reflected object represents a non-static final field in a class that is not a record class or hidden class, then enabling access will enable read access. Whether write access is allowed or not is checked when attempting to set the field value.

    Overrides:
      `setAccessible` in class `AccessibleObject`
    Parameters:
      `flag` - the new value for the `accessible` flag
    Throws:
      `InaccessibleObjectException` - if access cannot be enabled
    External Specifications
      - Java Native Interface Specification
    See Also:
      - `AccessibleObject.trySetAccessible()`
      - `MethodHandles.privateLookupIn(Class, MethodHandles.Lookup)`

  - ### getDeclaringClass

    public Class<?> getDeclaringClass()
    Returns the `Class` object representing the class or interface that declares the field represented by this `Field` object.
    Specified by:
      `getDeclaringClass` in interface `Member`
    Returns:
      an object representing the declaring class of the underlying member

  - ### getName

    public String getName()
    Returns the name of the field represented by this `Field` object.
    Specified by:
      `getName` in interface `Member`
    Returns:
      the simple name of the underlying member

  - ### getModifiers

    public int getModifiers()
    Returns the Java language modifiers for the field represented by this `Field` object, as an integer. The `Modifier` class should be used to decode the modifiers.
    Specified by:
      `getModifiers` in interface `Member`
    Returns:
      the Java language modifiers for the underlying member
    See Java Language Specification:
      8.3 Field Declarations
      9.3 Field (Constant) Declarations
    See Also:
      - `Modifier`
      - `accessFlags()`

  - ### accessFlags

    public Set<AccessFlag> accessFlags()
    Returns an unmodifiable set of the access flags for this field, possibly empty.
    Specified by:
      `accessFlags` in interface `Member`
    Returns:
      an unmodifiable set of the access flags for this field, possibly empty
    See Java Virtual Machine Specification:
      4.5 Fields
    Since:
      20
    See Also:
      - `getModifiers()`

  - ### isEnumConstant

    public boolean isEnumConstant()
    Returns `true` if this field represents an element of an enumerated class; returns `false` otherwise.
    Returns:
      `true` if and only if this field represents an element of an enumerated class.
    See Java Language Specification:
      8.9.1 Enum Constants
    Since:
      1.5

  - ### isSynthetic

    public boolean isSynthetic()
    Returns `true` if this field is a synthetic field; returns `false` otherwise.
    Specified by:
      `isSynthetic` in interface `Member`
    Returns:
      true if and only if this field is a synthetic field as defined by the Java Language Specification.
    Since:
      1.5
    See Also:
      - Java programming language and JVM modeling in core reflection

  - ### getType

    public Class<?> getType()
    Returns a `Class` object that identifies the declared type for the field represented by this `Field` object.
    Returns:
      a `Class` object identifying the declared type of the field represented by this object

  - ### getGenericType

    public Type getGenericType()
    Returns a `Type` object that represents the declared type for the field represented by this `Field` object.

    If the declared type of the field is a parameterized type, the `Type` object returned must accurately reflect the actual type arguments used in the source code.

    If the type of the underlying field is a type variable or a parameterized type, it is created. Otherwise, it is resolved.

    Returns:
      a `Type` object that represents the declared type for the field represented by this `Field` object
    Throws:
      `GenericSignatureFormatError` - if the generic field signature does not conform to the format specified in The Java Virtual Machine Specification
      `TypeNotPresentException` - if the generic type signature of the underlying field refers to a non-existent class or interface declaration
      `MalformedParameterizedTypeException` - if the generic signature of the underlying field refers to a parameterized type that cannot be instantiated for any reason
    Since:
      1.5

  - ### equals

    public boolean equals(Object obj)
    Compares this `Field` against the specified object. Returns true if the objects are the same. Two `Field` objects are the same if they were declared by the same class and have the same name and type.
    Overrides:
      `equals` in class `Object`
    Parameters:
      `obj` - the reference object with which to compare.
    Returns:
      `true` if this object is the same as the obj argument; `false` otherwise.
    See Also:
      - `Object.hashCode()`
      - `HashMap`

  - ### hashCode

    public int hashCode()
    Returns a hashcode for this `Field`. This is computed as the exclusive-or of the hashcodes for the underlying field's declaring class name and its name.
    Overrides:
      `hashCode` in class `Object`
    Returns:
      a hash code value for this object
    See Also:
      - `Object.equals(java.lang.Object)`
      - `System.identityHashCode(Object)`

  - ### toString

    public String toString()
    Returns a string describing this `Field`. The format is the access modifiers for the field, if any, followed by the field type, followed by a space, followed by the fully-qualified name of the class declaring the field, followed by a period, followed by the name of the field. For example:

           public static final int java.lang.Thread.MIN_PRIORITY
           private int java.io.FileDescriptor.fd

    The modifiers are placed in canonical order as specified by "The Java Language Specification". This is `public`, `protected` or `private` first, and then other modifiers in the following order: `static`, `final`, `transient`, `volatile`.

    Overrides:
      `toString` in class `Object`
    Returns:
      a string describing this `Field`
    See Java Language Specification:
      8.3.1 Field Modifiers

  - ### toGenericString

    public String toGenericString()
    Returns a string describing this `Field`, including its generic type. The format is the access modifiers for the field, if any, followed by the generic field type, followed by a space, followed by the fully-qualified name of the class declaring the field, followed by a period, followed by the name of the field.

    The modifiers are placed in canonical order as specified by "The Java Language Specification". This is `public`, `protected` or `private` first, and then other modifiers in the following order: `static`, `final`, `transient`, `volatile`.

    Returns:
      a string describing this `Field`, including its generic type
    See Java Language Specification:
      8.3.1 Field Modifiers
    Since:
      1.5

  - ### get

    public Object get(Object obj) throws IllegalArgumentException, IllegalAccessException
    Returns the value of the field represented by this `Field`, on the specified object. The value is automatically wrapped in an object if it has a primitive type.

    The underlying field's value is obtained as follows:

    If the underlying field is a static field, the `obj` argument is ignored; it may be null.

    Otherwise, the underlying field is an instance field. If the specified `obj` argument is null, the method throws a `NullPointerException`. If the specified object is not an instance of the class or interface declaring the underlying field, the method throws an `IllegalArgumentException`.

    If this `Field` object is enforcing Java language access control, and the underlying field is inaccessible, the method throws an `IllegalAccessException`. If the underlying field is static, the class that declared the field is initialized if it has not already been initialized.

    Otherwise, the value is retrieved from the underlying instance or static field. If the field has a primitive type, the value is wrapped in an object before being returned, otherwise it is returned as is.

    If the field is hidden in the type of `obj`, the field's value is obtained according to the preceding rules.

    Parameters:
      `obj` - object from which the represented field's value is to be extracted
    Returns:
      the value of the represented field in object `obj`; primitive values are wrapped in an appropriate object before being returned
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is inaccessible.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof).
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.

  - ### getBoolean

    public boolean getBoolean(Object obj) throws IllegalArgumentException, IllegalAccessException
    Gets the value of a static or instance `boolean` field.
    Parameters:
      `obj` - the object to extract the `boolean` value from
    Returns:
      the value of the `boolean` field
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is inaccessible.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if the field value cannot be converted to the type `boolean` by a widening conversion.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `get(Object)`

  - ### getByte

    public byte getByte(Object obj) throws IllegalArgumentException, IllegalAccessException
    Gets the value of a static or instance `byte` field.
    Parameters:
      `obj` - the object to extract the `byte` value from
    Returns:
      the value of the `byte` field
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is inaccessible.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if the field value cannot be converted to the type `byte` by a widening conversion.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `get(Object)`

  - ### getChar

    public char getChar(Object obj) throws IllegalArgumentException, IllegalAccessException
    Gets the value of a static or instance field of type `char` or of another primitive type convertible to type `char` via a widening conversion.
    Parameters:
      `obj` - the object to extract the `char` value from
    Returns:
      the value of the field converted to type `char`
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is inaccessible.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if the field value cannot be converted to the type `char` by a widening conversion.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `get(Object)`

  - ### getShort

    public short getShort(Object obj) throws IllegalArgumentException, IllegalAccessException
    Gets the value of a static or instance field of type `short` or of another primitive type convertible to type `short` via a widening conversion.
    Parameters:
      `obj` - the object to extract the `short` value from
    Returns:
      the value of the field converted to type `short`
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is inaccessible.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if the field value cannot be converted to the type `short` by a widening conversion.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `get(Object)`

  - ### getInt

    public int getInt(Object obj) throws IllegalArgumentException, IllegalAccessException
    Gets the value of a static or instance field of type `int` or of another primitive type convertible to type `int` via a widening conversion.
    Parameters:
      `obj` - the object to extract the `int` value from
    Returns:
      the value of the field converted to type `int`
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is inaccessible.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if the field value cannot be converted to the type `int` by a widening conversion.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `get(Object)`

  - ### getLong

    public long getLong(Object obj) throws IllegalArgumentException, IllegalAccessException
    Gets the value of a static or instance field of type `long` or of another primitive type convertible to type `long` via a widening conversion.
    Parameters:
      `obj` - the object to extract the `long` value from
    Returns:
      the value of the field converted to type `long`
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is inaccessible.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if the field value cannot be converted to the type `long` by a widening conversion.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `get(Object)`

  - ### getFloat

    public float getFloat(Object obj) throws IllegalArgumentException, IllegalAccessException
    Gets the value of a static or instance field of type `float` or of another primitive type convertible to type `float` via a widening conversion.
    Parameters:
      `obj` - the object to extract the `float` value from
    Returns:
      the value of the field converted to type `float`
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is inaccessible.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if the field value cannot be converted to the type `float` by a widening conversion.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `get(Object)`

  - ### getDouble

    public double getDouble(Object obj) throws IllegalArgumentException, IllegalAccessException
    Gets the value of a static or instance field of type `double` or of another primitive type convertible to type `double` via a widening conversion.
    Parameters:
      `obj` - the object to extract the `double` value from
    Returns:
      the value of the field converted to type `double`
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is inaccessible.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if the field value cannot be converted to the type `double` by a widening conversion.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `get(Object)`

  - ### set

    public void set(Object obj, Object value) throws IllegalArgumentException, IllegalAccessException
    Sets the field represented by this `Field` object on the specified object argument to the specified new value. The new value is automatically unwrapped if the underlying field has a primitive type.

    The operation proceeds as follows:

    If the underlying field is static, the `obj` argument is ignored; it may be null.

    Otherwise the underlying field is an instance field. If the specified object argument is null, the method throws a `NullPointerException`. If the specified object argument is not an instance of the class or interface declaring the underlying field, the method throws an `IllegalArgumentException`.

    If this `Field` object is enforcing Java language access control, and the underlying field is inaccessible, the method throws an `IllegalAccessException`.

    If the underlying field is final, this `Field` object has write access if and only if all of the following conditions are true, where `D` is the field's declaring class:

    - `setAccessible(true)` has succeeded for this `Field` object.
    - final field mutation is enabled for the caller's module.
    - At least one of the following conditions holds:
      1. `D` and the caller class are in the same module.
      2. The field is `public` and `D` is `public` in a package that the module containing `D` exports to at least the caller's module.
      3. `D` is in a package that is open to the caller's module.
    - `D` is not a record class.
    - `D` is not a hidden class.
    - The field is non-static.

    If any of the above conditions is not met, this method throws an `IllegalAccessException`.

    These conditions are more restrictive than the conditions specified by `setAccessible(boolean)` to suppress access checks. In particular, updating a module to export or open a package cannot be used to allow write access to final fields with the `set` methods defined by `Field`. Condition (b) is not met if the module containing `D` has been updated with addExports to export the package to the caller's module. Condition (c) is not met if the module containing `D` has been updated with addOpens to open the package to the caller's module.

    This method may be called by JNI code with no caller class on the stack. In that case, and when the underlying field is final, this `Field` object has write access if and only if all of the following conditions are true, where `D` is the field's declaring class:

    - `setAccessible(true)` has succeeded for this `Field` object.
    - final field mutation is enabled for the unnamed module.
    - The field is `public` and `D` is `public` in a package that is exported to all modules.
    - `D` is not a record class.
    - `D` is not a hidden class.
    - The field is non-static.

    If any of the above conditions is not met, this method throws an `IllegalAccessException`.

    Setting a final field in this way is meaningful only during deserialization or reconstruction of instances of classes with blank final fields, before they are made available for access by other parts of a program. Use in any other context may have unpredictable effects, including cases in which other parts of a program continue to use the original value of this field.

    If the underlying field is of a primitive type, an unwrapping conversion is attempted to convert the new value to a value of a primitive type. If this attempt fails, the method throws an `IllegalArgumentException`.

    If, after possible unwrapping, the new value cannot be converted to the type of the underlying field by an identity or widening conversion, the method throws an `IllegalArgumentException`.

    If the underlying field is static, the class that declared the field is initialized if it has not already been initialized.

    The field is set to the possibly unwrapped and widened new value.

    If the field is hidden in the type of `obj`, the field's value is set according to the preceding rules.

    Parameters:
      `obj` - the object whose field should be modified
      `value` - the new value for the field of `obj` being modified
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is inaccessible or final; or if this `Field` object has no write access.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if an unwrapping conversion fails.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - Mutation methods

  - ### setBoolean

    public void setBoolean(Object obj, boolean z) throws IllegalArgumentException, IllegalAccessException
    Sets the value of a field as a `boolean` on the specified object. This method is equivalent to `set(obj, zObj)`, where `zObj` is a `Boolean` object and `zObj.booleanValue() == z`.
    Parameters:
      `obj` - the object whose field should be modified
      `z` - the new value for the field of `obj` being modified
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is either inaccessible or final; or if this `Field` object has no write access.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if an unwrapping conversion fails.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `set(Object, Object)`

  - ### setByte

    public void setByte(Object obj, byte b) throws IllegalArgumentException, IllegalAccessException
    Sets the value of a field as a `byte` on the specified object. This method is equivalent to `set(obj, bObj)`, where `bObj` is a `Byte` object and `bObj.byteValue() == b`.
    Parameters:
      `obj` - the object whose field should be modified
      `b` - the new value for the field of `obj` being modified
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is either inaccessible or final; or if this `Field` object has no write access.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if an unwrapping conversion fails.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `set(Object, Object)`

  - ### setChar

    public void setChar(Object obj, char c) throws IllegalArgumentException, IllegalAccessException
    Sets the value of a field as a `char` on the specified object. This method is equivalent to `set(obj, cObj)`, where `cObj` is a `Character` object and `cObj.charValue() == c`.
    Parameters:
      `obj` - the object whose field should be modified
      `c` - the new value for the field of `obj` being modified
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is either inaccessible or final; or if this `Field` object has no write access.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if an unwrapping conversion fails.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `set(Object, Object)`

  - ### setShort

    public void setShort(Object obj, short s) throws IllegalArgumentException, IllegalAccessException
    Sets the value of a field as a `short` on the specified object. This method is equivalent to `set(obj, sObj)`, where `sObj` is a `Short` object and `sObj.shortValue() == s`.
    Parameters:
      `obj` - the object whose field should be modified
      `s` - the new value for the field of `obj` being modified
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is either inaccessible or final; or if this `Field` object has no write access.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if an unwrapping conversion fails.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `set(Object, Object)`

  - ### setInt

    public void setInt(Object obj, int i) throws IllegalArgumentException, IllegalAccessException
    Sets the value of a field as an `int` on the specified object. This method is equivalent to `set(obj, iObj)`, where `iObj` is an `Integer` object and `iObj.intValue() == i`.
    Parameters:
      `obj` - the object whose field should be modified
      `i` - the new value for the field of `obj` being modified
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is either inaccessible or final; or if this `Field` object has no write access.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if an unwrapping conversion fails.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `set(Object, Object)`

  - ### setLong

    public void setLong(Object obj, long l) throws IllegalArgumentException, IllegalAccessException
    Sets the value of a field as a `long` on the specified object. This method is equivalent to `set(obj, lObj)`, where `lObj` is a `Long` object and `lObj.longValue() == l`.
    Parameters:
      `obj` - the object whose field should be modified
      `l` - the new value for the field of `obj` being modified
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is either inaccessible or final; or if this `Field` object has no write access.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if an unwrapping conversion fails.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `set(Object, Object)`

  - ### setFloat

    public void setFloat(Object obj, float f) throws IllegalArgumentException, IllegalAccessException
    Sets the value of a field as a `float` on the specified object. This method is equivalent to `set(obj, fObj)`, where `fObj` is a `Float` object and `fObj.floatValue() == f`.
    Parameters:
      `obj` - the object whose field should be modified
      `f` - the new value for the field of `obj` being modified
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is either inaccessible or final; or if this `Field` object has no write access.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if an unwrapping conversion fails.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `set(Object, Object)`

  - ### setDouble

    public void setDouble(Object obj, double d) throws IllegalArgumentException, IllegalAccessException
    Sets the value of a field as a `double` on the specified object. This method is equivalent to `set(obj, dObj)`, where `dObj` is a `Double` object and `dObj.doubleValue() == d`.
    Parameters:
      `obj` - the object whose field should be modified
      `d` - the new value for the field of `obj` being modified
    Throws:
      `IllegalAccessException` - if this `Field` object is enforcing Java language access control and the underlying field is either inaccessible or final; or if this `Field` object has no write access.
      `IllegalArgumentException` - if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof), or if an unwrapping conversion fails.
      `NullPointerException` - if the specified object is null and the field is an instance field.
      `ExceptionInInitializerError` - if the initialization provoked by this method fails.
    See Also:
      - `set(Object, Object)`

  - ### getAnnotation

    public <T extends Annotation> T getAnnotation(Class<T> annotationClass)
    Returns this element's annotation for the specified type if such an annotation is present, else null.

    Note that any annotation returned by this method is a declaration annotation.

    Specified by:
      `getAnnotation` in interface `AnnotatedElement`
    Overrides:
      `getAnnotation` in class `AccessibleObject`
    Type Parameters:
      `T` - the type of the annotation to query for and return if present
    Parameters:
      `annotationClass` - the Class object corresponding to the annotation type
    Returns:
      this element's annotation for the specified annotation type if present on this element, else null
    Throws:
      `NullPointerException` - if the given annotation class is null
    Since:
      1.5

  - ### getAnnotationsByType

    public <T extends Annotation> T[] getAnnotationsByType(Class<T> annotationClass)
    Returns annotations that are associated with this element. If there are no annotations associated with this element, the return value is an array of length 0. The difference between this method and `AnnotatedElement.getAnnotation(Class)` is that this method detects if its argument is a repeatable annotation type (JLS 9.6), and if so, attempts to find one or more annotations of that type by "looking through" a container annotation. The caller of this method is free to modify the returned array; it will have no effect on the arrays returned to other callers.

    Note that any annotations returned by this method are declaration annotations.

    Specified by:
      `getAnnotationsByType` in interface `AnnotatedElement`
    Overrides:
      `getAnnotationsByType` in class `AccessibleObject`
    Type Parameters:
      `T` - the type of the annotation to query for and return if present
    Parameters:
      `annotationClass` - the Class object corresponding to the annotation type
    Returns:
      all this element's annotations for the specified annotation type if associated with this element, else an array of length zero
    Throws:
      `NullPointerException` - if the given annotation class is null
    Since:
      1.8

  - ### getAnnotatedType

    public AnnotatedType getAnnotatedType()
    Returns an AnnotatedType object that represents the use of a type to specify the declared type of the field represented by this Field.
    Returns:
      an object representing the declared type of the field represented by this Field
    Since:
      1.8