org.bbottema.javareflection

Class ClassUtils

java.lang.Object

org.bbottema.javareflection.ClassUtils

public final class ClassUtils
extends Object

Utility with convenience methods that operate on the class level.

• With this helper class you can locate and/or load classes. An advanced Class lookup (locateClass(String, boolean, ClassLoader)), that allows a full scan (to try all packages known) and an optional ExternalClassLoader instance that is able to actually compile a .java file on the fly and load its compile .class file
• create a new instance while handling all the exceptions
• find fields or assign values to fields, using casting, autoboxing or type conversions
• simply give back a list of field / method names

Constructor Summary

Constructors

Constructor and Description
ClassUtils()

Method Summary

Modifier and Type	Method and Description
static @Nullable Object	assignToField(Object o, String property, Object value) Assigns a value to a field id on the given object o.
static Set<String>	collectMethodNames(Class<?> dataType, boolean publicOnly) Returns a list of names that represent the methods on an Object
static Set<Method>	collectMethods(Class<?> dataType, boolean publicOnly) Returns a list of names that represent the methods on an Object
static @NotNull Collection<String>	collectPropertyNames(Object subject) Returns a list of names that represent the fields on an Object.
static @Nullable Class<?>	locateClass(String className, boolean fullscan, @Nullable ClassLoader classLoader) Searches the JVM and optionally all of its packages
static @Nullable Class<?>	locateClass(String fullClassName, @Nullable ClassLoader classLoader) This function dynamically tries to locate a class.
static @Nullable Class<?>	locateClass(String className, @Nullable String inPackage, @Nullable ClassLoader classLoader)
static <T> T	newInstanceSimple(Class<T> _class) Simply calls Class.newInstance() and hides the exception handling boilerplate code.
static void	resetCache()
static @Nullable Field	solveField(Object o, String fieldName) Returns a field from the given object that goes by the name of fieldName.

Methods inherited from class java.lang.Object

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

Constructor Detail

ClassUtils

public ClassUtils()

Method Detail

resetCache

public static void resetCache()

locateClass

@Nullable
public static @Nullable Class<?> locateClass(String className,
                                                        boolean fullscan,
                                                        @Nullable
                                                        @Nullable ClassLoader classLoader)

Searches the JVM and optionally all of its packages

Parameters:

className - The name of the class to locate.

fullscan - Whether a full scan through all available java packages is required.

classLoader - Optional user-provided classloader.

Returns:

The Class reference if found or null otherwise.

locateClass

@Nullable
public static @Nullable Class<?> locateClass(String className,
                                                        @Nullable
                                                        @Nullable String inPackage,
                                                        @Nullable
                                                        @Nullable ClassLoader classLoader)

locateClass

@Nullable
public static @Nullable Class<?> locateClass(String fullClassName,
                                                        @Nullable
                                                        @Nullable ClassLoader classLoader)

This function dynamically tries to locate a class. First it searches the class-cache list, then it tries to get it from the Virtual Machine using Class.forName(String).

Parameters:

fullClassName - The Class that needs to be found.

classLoader - Optional user-provided classloader.

Returns:

The Class object found from cache or VM.

newInstanceSimple

@NotNull
public static <T> T newInstanceSimple(Class<T> _class)

Simply calls Class.newInstance() and hides the exception handling boilerplate code.

Type Parameters:

T - Type used to parameterize the return instance.

Parameters:

_class - The datatype for which we need to create a new instance of.

Returns:

A new parameterized instance of the given type.

solveField

@Nullable
public static @Nullable Field solveField(Object o,
                                                    String fieldName)

Returns a field from the given object that goes by the name of fieldName. If o is a Class object, a static field will be returned.

Parameters:

o - The reference to the object to fetch the property value from.

fieldName - The identifier or name of the member field/property.

Returns:

The value of the Field.

assignToField

@Nullable
public static @Nullable Object assignToField(Object o,
                                                        String property,
                                                        Object value)
                                                 throws IllegalAccessException,
                                                        NoSuchFieldException

Assigns a value to a field id on the given object o. If a simple assignment fails, a common conversion will be attempted.

Parameters:

o - The object to find the field on.

property - The name of the field we're assigning the value to.

value - The value to assign to the field, may be converted to the field's type through common conversion.

Returns:

The actual value that was assigned (the original or the converted value).

Throws:

IllegalAccessException - Thrown by Field.set(Object, Object)

NoSuchFieldException - Thrown if the Field could not be found, even after trying to convert the value to the target type.

See Also:

ValueConversionHelper.convert(Object, Class)

collectPropertyNames

@NotNull
public static @NotNull Collection<String> collectPropertyNames(Object subject)

Returns a list of names that represent the fields on an Object.

Parameters:

subject - The Object who's properties/fields need to be reflected.

Returns:

A list of names that represent the fields on the given Object.

collectMethodNames

public static Set<String> collectMethodNames(Class<?> dataType,
                                             boolean publicOnly)

Returns a list of names that represent the methods on an Object

Parameters:

publicOnly - Indicates whether only public (albeit inherited) members should be returned. Else also private and protected methods will be included

Returns:

Returns a list with methods, either Methods.

collectMethods

public static Set<Method> collectMethods(Class<?> dataType,
                                         boolean publicOnly)

Returns a list of names that represent the methods on an Object

Parameters:

publicOnly - Indicates whether only public (albeit inherited) members should be returned. Else also private and protected methods will be included

Returns:

Returns a list with methods, either Methods.