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, Class<?> boundaryMarker, EnumSet<MethodModifier> methodModifiers)
static Set<Method>	collectMethods(Class<?> dataType, Class<?> boundaryMarker, EnumSet<MethodModifier> methodModifiers) Returns a list of names that represent the methods on an Object
static Set<Method>	collectMethodsByName(Class<?> type, Class<?> boundaryMarker, EnumSet<MethodModifier> methodModifiers, String methodName)
static Map<String,Set<Method>>	collectMethodsMappingToName(Class<?> type, Class<?> boundaryMarker, EnumSet<MethodModifier> methodModifiers)
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(Class<?> _class, String fieldName) Returns a field from the given Class that goes by the name of fieldName.
static @Nullable Field	solveField(Object object, String fieldName) Delegates to solveField(Class, String) by using the class of given object object or if object itself if it ss a class.
static <T> T	solveFieldValue(Object object, String fieldName) Gets value from the field returned by solveField(Object, String).;

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.

solveFieldValue

@Nullable
public static <T> T solveFieldValue(Object object,
                                               String fieldName)

Gets value from the field returned by solveField(Object, String).;

solveField

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

Delegates to solveField(Class, String) by using the class of given object object or if object itself if it ss a class.

solveField

@Nullable
public static @Nullable Field solveField(Class<?> _class,
                                                    String fieldName)

Returns a field from the given Class that goes by the name of fieldName. Will search for fields on implemented interfaces and superclasses.

Parameters:

_class - The reference to the Class to fetch the field 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,
                                             Class<?> boundaryMarker,
                                             EnumSet<MethodModifier> methodModifiers)

Returns:

Returns the result of collectMethods(Class, Class, EnumSet) mapped to the method names.

collectMethodsByName

public static Set<Method> collectMethodsByName(Class<?> type,
                                               Class<?> boundaryMarker,
                                               EnumSet<MethodModifier> methodModifiers,
                                               String methodName)

Returns:

The result of collectMethodsMappingToName(Class, Class, EnumSet) filtered on method name.

collectMethodsMappingToName

public static Map<String,Set<Method>> collectMethodsMappingToName(Class<?> type,
                                                                  Class<?> boundaryMarker,
                                                                  EnumSet<MethodModifier> methodModifiers)

Returns:

The result of collectMethods(Class, Class, EnumSet) filtered on method name.

collectMethods

public static Set<Method> collectMethods(Class<?> dataType,
                                         Class<?> boundaryMarker,
                                         EnumSet<MethodModifier> methodModifiers)

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

Parameters:

methodModifiers - List of method modifiers that will match any method that has one of them.

boundaryMarker - Optional type to limit (including) how far back up the inheritance chain we go for discovering methods.

Returns:

Returns a list with methods, either Methods.