Package org.apache.commons.lang3.reflect

Class FieldUtils

  • public class FieldUtils
extends Object
    Utilities for working with Fields by reflection. Adapted and refactored from the dormant [reflect] Commons sandbox component.

    The ability is provided to break the scoping restrictions coded by the programmer. This can allow fields to be changed that shouldn't be. This facility should be used with care.

    Since:
    2.5

    • Constructor Detail

      • FieldUtils

        public FieldUtils()
        FieldUtils instances should NOT be constructed in standard programming.

        This constructor is public to permit tools that require a JavaBean instance to operate.

    • Method Detail

      • getField

        public static Field getField​(Class<?> cls,
                             String fieldName)
        Gets an accessible Field by name respecting scope. Superclasses/interfaces will be considered.
        Parameters:
        cls - the Class to reflect, must not be null
        fieldName - the field name to obtain
        Returns:
        the Field object
        Throws:
        IllegalArgumentException - if the class is null, or the field name is blank or empty

      • getField

        public static Field getField​(Class<?> cls,
                             String fieldName,
                             boolean forceAccess)
        Gets an accessible Field by name, breaking scope if requested. Superclasses/interfaces will be considered.
        Parameters:
        cls - the Class to reflect, must not be null
        fieldName - the field name to obtain
        forceAccess - whether to break scope restrictions using the AccessibleObject.setAccessible(boolean) method. false will only match public fields.
        Returns:
        the Field object
        Throws:
        NullPointerException - if the class is null
        IllegalArgumentException - if the field name is blank or empty or is matched at multiple places in the inheritance hierarchy

      • getDeclaredField

        public static Field getDeclaredField​(Class<?> cls,
                                     String fieldName)
        Gets an accessible Field by name respecting scope. Only the specified class will be considered.
        Parameters:
        cls - the Class to reflect, must not be null
        fieldName - the field name to obtain
        Returns:
        the Field object
        Throws:
        IllegalArgumentException - if the class is null, or the field name is blank or empty

      • getDeclaredField

        public static Field getDeclaredField​(Class<?> cls,
                                     String fieldName,
                                     boolean forceAccess)
        Gets an accessible Field by name, breaking scope if requested. Only the specified class will be considered.
        Parameters:
        cls - the Class to reflect, must not be null
        fieldName - the field name to obtain
        forceAccess - whether to break scope restrictions using the AccessibleObject.setAccessible(boolean) method. false will only match public fields.
        Returns:
        the Field object
        Throws:
        IllegalArgumentException - if the class is null, or the field name is blank or empty

      • getAllFields

        public static Field[] getAllFields​(Class<?> cls)
        Gets all fields of the given class and its parents (if any).
        Parameters:
        cls - the Class to query
        Returns:
        an array of Fields (possibly empty).
        Throws:
        IllegalArgumentException - if the class is null
        Since:
        3.2

      • getAllFieldsList

        public static List<Field> getAllFieldsList​(Class<?> cls)
        Gets all fields of the given class and its parents (if any).
        Parameters:
        cls - the Class to query
        Returns:
        an array of Fields (possibly empty).
        Throws:
        IllegalArgumentException - if the class is null
        Since:
        3.2

      • getFieldsWithAnnotation

        public static Field[] getFieldsWithAnnotation​(Class<?> cls,
                                              Class<? extends Annotation> annotationCls)
        Gets all fields of the given class and its parents (if any) that are annotated with the given annotation.
        Parameters:
        cls - the Class to query
        annotationCls - the Annotation that must be present on a field to be matched
        Returns:
        an array of Fields (possibly empty).
        Throws:
        IllegalArgumentException - if the class or annotation are null
        Since:
        3.4

      • getFieldsListWithAnnotation

        public static List<Field> getFieldsListWithAnnotation​(Class<?> cls,
                                                      Class<? extends Annotation> annotationCls)
        Gets all fields of the given class and its parents (if any) that are annotated with the given annotation.
        Parameters:
        cls - the Class to query
        annotationCls - the Annotation that must be present on a field to be matched
        Returns:
        a list of Fields (possibly empty).
        Throws:
        IllegalArgumentException - if the class or annotation are null
        Since:
        3.4

      • readStaticField

        public static Object readStaticField​(Class<?> cls,
                                     String fieldName)
                              throws IllegalAccessException
        Reads the named public static Field. Superclasses will be considered.
        Parameters:
        cls - the Class to reflect, must not be null
        fieldName - the field name to obtain
        Returns:
        the value of the field
        Throws:
        IllegalArgumentException - if the class is null, or the field name is blank or empty, is not static, or could not be found
        IllegalAccessException - if the field is not accessible

      • readDeclaredStaticField

        public static Object readDeclaredStaticField​(Class<?> cls,
                                             String fieldName)
                                      throws IllegalAccessException
        Gets the value of a static Field by name. The field must be public. Only the specified class will be considered.
        Parameters:
        cls - the Class to reflect, must not be null
        fieldName - the field name to obtain
        Returns:
        the value of the field
        Throws:
        IllegalArgumentException - if the class is null, or the field name is blank or empty, is not static, or could not be found
        IllegalAccessException - if the field is not accessible

      • readDeclaredStaticField

        public static Object readDeclaredStaticField​(Class<?> cls,
                                             String fieldName,
                                             boolean forceAccess)
                                      throws IllegalAccessException
        Gets the value of a static Field by name. Only the specified class will be considered.
        Parameters:
        cls - the Class to reflect, must not be null
        fieldName - the field name to obtain
        forceAccess - whether to break scope restrictions using the AccessibleObject.setAccessible(boolean) method. false will only match public fields.
        Returns:
        the Field object
        Throws:
        IllegalArgumentException - if the class is null, or the field name is blank or empty, is not static, or could not be found
        IllegalAccessException - if the field is not made accessible

      • readField

        public static Object readField​(Object target,
                               String fieldName)
                        throws IllegalAccessException
        Reads the named public Field. Superclasses will be considered.
        Parameters:
        target - the object to reflect, must not be null
        fieldName - the field name to obtain
        Returns:
        the value of the field
        Throws:
        IllegalArgumentException - if the class is null, or the field name is blank or empty or could not be found
        IllegalAccessException - if the named field is not public

      • readDeclaredField

        public static Object readDeclaredField​(Object target,
                                       String fieldName)
                                throws IllegalAccessException
        Reads the named public Field. Only the class of the specified object will be considered.
        Parameters:
        target - the object to reflect, must not be null
        fieldName - the field name to obtain
        Returns:
        the value of the field
        Throws:
        IllegalArgumentException - if target is null, or the field name is blank or empty or could not be found
        IllegalAccessException - if the named field is not public

      • readDeclaredField

        public static Object readDeclaredField​(Object target,
                                       String fieldName,
                                       boolean forceAccess)
                                throws IllegalAccessException
        Gets a Field value by name. Only the class of the specified object will be considered.
        Parameters:
        target - the object to reflect, must not be null
        fieldName - the field name to obtain
        forceAccess - whether to break scope restrictions using the AccessibleObject.setAccessible(boolean) method. false will only match public fields.
        Returns:
        the Field object
        Throws:
        IllegalArgumentException - if target is null, or the field name is blank or empty or could not be found
        IllegalAccessException - if the field is not made accessible

      • writeStaticField

        public static void writeStaticField​(Class<?> cls,
                                    String fieldName,
                                    Object value)
                             throws IllegalAccessException
        Writes a named public static Field. Superclasses will be considered.
        Parameters:
        cls - Class on which the field is to be found
        fieldName - to write
        value - to set
        Throws:
        IllegalArgumentException - if cls is null, the field name is blank or empty, the field cannot be located or is not static, or value is not assignable
        IllegalAccessException - if the field is not public or is final

      • writeStaticField

        public static void writeStaticField​(Class<?> cls,
                                    String fieldName,
                                    Object value,
                                    boolean forceAccess)
                             throws IllegalAccessException
        Writes a named static Field. Superclasses will be considered.
        Parameters:
        cls - Class on which the field is to be found
        fieldName - to write
        value - to set
        forceAccess - whether to break scope restrictions using the AccessibleObject.setAccessible(boolean) method. false will only match public fields.
        Throws:
        IllegalArgumentException - if cls is null, the field name is blank or empty, the field cannot be located or is not static, or value is not assignable
        IllegalAccessException - if the field is not made accessible or is final

      • writeDeclaredStaticField

        public static void writeDeclaredStaticField​(Class<?> cls,
                                            String fieldName,
                                            Object value)
                                     throws IllegalAccessException
        Writes a named public static Field. Only the specified class will be considered.
        Parameters:
        cls - Class on which the field is to be found
        fieldName - to write
        value - to set
        Throws:
        IllegalArgumentException - if cls is null, the field name is blank or empty, the field cannot be located or is not static, or value is not assignable
        IllegalAccessException - if the field is not public or is final

      • writeDeclaredStaticField

        public static void writeDeclaredStaticField​(Class<?> cls,
                                            String fieldName,
                                            Object value,
                                            boolean forceAccess)
                                     throws IllegalAccessException
        Writes a named static Field. Only the specified class will be considered.
        Parameters:
        cls - Class on which the field is to be found
        fieldName - to write
        value - to set
        forceAccess - whether to break scope restrictions using the AccessibleObject#setAccessible(boolean) method. false will only match public fields.
        Throws:
        IllegalArgumentException - if cls is null, the field name is blank or empty, the field cannot be located or is not static, or value is not assignable
        IllegalAccessException - if the field is not made accessible or is final

      • writeField

        public static void writeField​(Field field,
                              Object target,
                              Object value)
                       throws IllegalAccessException
        Writes an accessible Field.
        Parameters:
        field - to write
        target - the object to call on, may be null for static fields
        value - to set
        Throws:
        IllegalAccessException - if the field or target is null, the field is not accessible or is final, or value is not assignable

      • removeFinalModifier

        public static void removeFinalModifier​(Field field)
        Removes the final modifier from a Field.
        Parameters:
        field - to remove the final modifier
        Throws:
        IllegalArgumentException - if the field is null
        Since:
        3.2

      • removeFinalModifier

        @Deprecated
public static void removeFinalModifier​(Field field,
                                       boolean forceAccess)
        Deprecated.
        As of Java 12, we can no longer drop the final modifier, thus rendering this method obsolete. The JDK discussion about this change can be found here: http://mail.openjdk.java.net/pipermail/core-libs-dev/2018-November/056486.html
        Removes the final modifier from a Field.
        Parameters:
        field - to remove the final modifier
        forceAccess - whether to break scope restrictions using the AccessibleObject.setAccessible(boolean) method. false will only match public fields.
        Throws:
        IllegalArgumentException - if the field is null
        Since:
        3.3

      • writeField

        public static void writeField​(Object target,
                              String fieldName,
                              Object value)
                       throws IllegalAccessException
        Writes a public Field. Superclasses will be considered.
        Parameters:
        target - the object to reflect, must not be null
        fieldName - the field name to obtain
        value - to set
        Throws:
        IllegalArgumentException - if target is null, fieldName is blank or empty or could not be found, or value is not assignable
        IllegalAccessException - if the field is not accessible

      • writeDeclaredField

        public static void writeDeclaredField​(Object target,
                                      String fieldName,
                                      Object value)
                               throws IllegalAccessException
        Writes a public Field. Only the specified class will be considered.
        Parameters:
        target - the object to reflect, must not be null
        fieldName - the field name to obtain
        value - to set
        Throws:
        IllegalArgumentException - if target is null, fieldName is blank or empty or could not be found, or value is not assignable
        IllegalAccessException - if the field is not made accessible

      • writeDeclaredField

        public static void writeDeclaredField​(Object target,
                                      String fieldName,
                                      Object value,
                                      boolean forceAccess)
                               throws IllegalAccessException
        Writes a public Field. Only the specified class will be considered.
        Parameters:
        target - the object to reflect, must not be null
        fieldName - the field name to obtain
        value - to set
        forceAccess - whether to break scope restrictions using the AccessibleObject.setAccessible(boolean) method. false will only match public fields.
        Throws:
        IllegalArgumentException - if target is null, fieldName is blank or empty or could not be found, or value is not assignable
        IllegalAccessException - if the field is not made accessible