Class HiddenClassesExamples

java.lang.Object

net.jrodolfo.java_evolution.java15.hidden_classes.HiddenClassesExamples

public class HiddenClassesExamples
extends Object

Demonstrates hidden classes, introduced in Java 15 by JEP 371.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	HiddenClassesExamples.Template	Compiled template used as class-file bytes for the hidden class definition.

Constructor Summary

Constructors

Constructor	Description
HiddenClassesExamples()

Method Summary

Modifier and Type	Method	Description
boolean	canFindByName(Class<?> hiddenClass)	Checks whether normal class-name lookup can discover a hidden class.
Class<?>	defineHiddenTemplateClass()	Defines a hidden class from the compiled bytes of the nested template class.
String	invokeHiddenClassMethod(Class<?> hiddenClass)	Invokes behavior on an instance of the hidden class.
boolean	isHidden(Class<?> type)	Reports whether a class is hidden.

Methods inherited from class Object

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

Constructor Details

HiddenClassesExamples

public HiddenClassesExamples()

Method Details

defineHiddenTemplateClass

public Class<?> defineHiddenTemplateClass()
                                   throws IOException,
IllegalAccessException

Defines a hidden class from the compiled bytes of the nested template class.

Returns:

hidden class metadata

Throws:

IOException - when the template class bytes cannot be read

IllegalAccessException - when the lookup cannot define the hidden class

isHidden

public boolean isHidden(Class<?> type)

Reports whether a class is hidden.

Parameters:

type - class to inspect

Returns:

whether the class is hidden

invokeHiddenClassMethod

public String invokeHiddenClassMethod(Class<?> hiddenClass)
                               throws NoSuchMethodException,
InvocationTargetException,
InstantiationException,
IllegalAccessException

Invokes behavior on an instance of the hidden class.

Parameters:

hiddenClass - hidden class to instantiate

Returns:

message returned by the hidden instance

Throws:

NoSuchMethodException - when the expected constructor or method is missing

InvocationTargetException - when the constructor or method throws an exception

InstantiationException - when the hidden class cannot be instantiated

IllegalAccessException - when access checks reject construction or invocation

canFindByName

public boolean canFindByName(Class<?> hiddenClass)

Checks whether normal class-name lookup can discover a hidden class.

Parameters:

hiddenClass - hidden class to look up by name

Returns:

whether Class.forName(String) finds the hidden class