Package pro.johndunlap.getopt

Class ReflectionUtil

java.lang.Object

pro.johndunlap.getopt.ReflectionUtil

public class ReflectionUtil
extends Object

A utility class which contains reflective methods for working with Java objects.

Author:

John Dunlap

Method Summary

Modifier and Type	Method	Description
static Method	findGetterMethod(Field field)	Attempts to find a getter method for the given field.
static Method	findSetterMethod(Field field)	Attempts to find a setter method for the given field.
static Object	getFieldValue(Field field, Object instance)	This method attempts to get the value of a field without violating its declared access modifiers.
static Constructor<?>	getNoArgConstructor(Class<?> clazz)	Attempts to find a no-arg constructor for the given class.
static <T> T	instantiate(Class<?> type)	This method attempts to construct an instance of the given class without violating its declared access modifiers.
static Object	instantiateCollection(Class<Collection<?>> collectionClass)
boolean	isArray(Class<?> clazz)
static boolean	isBoolean(Class<?> type)	Returns true if the given type is a byte type (Boolean or boolean).
static boolean	isByte(Class<?> type)	Returns true if the given type is a byte type (Byte or byte).
static boolean	isCharacter(Class<?> type)	Returns true if the given type is a character type (Character or char).
static boolean	isCollection(Class<?> clazz)
static boolean	isDouble(Class<?> type)	Returns true if the given type is a double type (Double or double).
static boolean	isFloat(Class<?> type)	Returns true if the given type is a float type (Float or float).
static boolean	isInteger(Class<?> type)	Returns true if the given type is a byte type (Integer or int).
static boolean	isLong(Class<?> type)	Returns true if the given type is a byte type (Long or long).
static boolean	isShort(Class<?> type)	Returns true if the given type is a byte type (Short or short).
static <T> T	parse(Class<T> fieldType, String value)	Parses a string value into an object of the given type.
static void	setFieldValue(Field field, Object instance, Object value)	This method attempts to set the value of a field without violating its declared access modifiers.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getFieldValue

public static Object getFieldValue(Field field,
                                   Object instance)
                            throws IllegalAccessException

This method attempts to get the value of a field without violating its declared access modifiers. However, if it is unable to do so, it will override the access modifiers and try again. If available, getter methods will be used. Direct field access will only be used as a last resort. However, if there is a public field with a private getter (unlikely), then public field will be used. If both the field and the getter are private, the getter will be used.

Parameters:

field - The field from which the value should be taken

instance - The instance from which the value should be taken

Returns:

The value of the field

Throws:

IllegalAccessException - Thrown if the field or method is inaccessible

instantiate

public static <T> T instantiate(Class<?> type)
                         throws MissingNoArgConstructorException

This method attempts to construct an instance of the given class without violating its declared access modifiers.

Type Parameters:

T - The type of object to instantiate

Parameters:

type - The type of object to instantiate

Returns:

The instantiated object

Throws:

MissingNoArgConstructorException - Thrown if the class does not have a no-arg constructor

setFieldValue

public static void setFieldValue(Field field,
                                 Object instance,
                                 Object value)
                          throws IllegalAccessException

This method attempts to set the value of a field without violating its declared access modifiers. However, if it is unable to do so, it will override the access modifiers and try again. If available, setter methods will be used. Direct field access will only be used as a last resort. However, if there is a public field with a private setter (unlikely), then public field will be used. If both the field and the setter are private,the setter will be used.

Parameters:

field - The field to which the value should be set

instance - The instance to which the value should be set

value - The value to set

Throws:

IllegalAccessException - Thrown if the field or method is inaccessible

findSetterMethod

public static Method findSetterMethod(Field field)

Attempts to find a setter method for the given field. If one is not found, null is returned.

Parameters:

field - The field for which to find a setter method

Returns:

The setter method, or null if one is not found

findGetterMethod

public static Method findGetterMethod(Field field)

Attempts to find a getter method for the given field. If one is not found, null is returned.

Parameters:

field - The field for which to find a getter method

Returns:

The getter method, or null if one is not found

getNoArgConstructor

public static Constructor<?> getNoArgConstructor(Class<?> clazz)

Attempts to find a no-arg constructor for the given class. If one is not found, null is returned.

Parameters:

clazz - The class for which to find a no-arg constructor

Returns:

The no-arg constructor, or null if one is not found

isCollection

public static boolean isCollection(Class<?> clazz)

isArray

public boolean isArray(Class<?> clazz)

instantiateCollection

public static Object instantiateCollection(Class<Collection<?>> collectionClass)

parse

public static <T> T parse(Class<T> fieldType,
                          String value)
                   throws ParseException

Parses a string value into an object of the given type.

Type Parameters:

T - The type of the object to be returned

Parameters:

fieldType - The type of the object to be returned

value - The string value to be parsed

Returns:

The parsed value

Throws:

ParseException - Thrown if the value cannot be parsed into the given type

isBoolean

public static boolean isBoolean(Class<?> type)

Returns true if the given type is a byte type (Boolean or boolean).

Parameters:

type - The type to check

Returns:

True if the given type is a boolean type

isInteger

public static boolean isInteger(Class<?> type)

Returns true if the given type is a byte type (Integer or int).

Parameters:

type - The type to check

Returns:

True if the given type is a byte type

isShort

public static boolean isShort(Class<?> type)

Returns true if the given type is a byte type (Short or short).

Parameters:

type - The type to check

Returns:

True if the given type is a short type

isLong

public static boolean isLong(Class<?> type)

Returns true if the given type is a byte type (Long or long).

Parameters:

type - The type to check

Returns:

True if the given type is a long type

isFloat

public static boolean isFloat(Class<?> type)

Returns true if the given type is a float type (Float or float).

Parameters:

type - The type to check

Returns:

True if the given type is a float type

isDouble

public static boolean isDouble(Class<?> type)

Returns true if the given type is a double type (Double or double).

Parameters:

type - The type to check

Returns:

True if the given type is a double type

isByte

public static boolean isByte(Class<?> type)

Returns true if the given type is a byte type (Byte or byte).

Parameters:

type - The type to check

Returns:

True if the given type is a byte type

isCharacter

public static boolean isCharacter(Class<?> type)

Returns true if the given type is a character type (Character or char).

Parameters:

type - The type to check

Returns:

True if the given type is a character type