Package org.stianloader.mrjmania

Class MRJURLClassLoader

java.lang.Object

java.lang.ClassLoader

java.security.SecureClassLoader

java.net.URLClassLoader

org.stianloader.mrjmania.MRJURLClassLoader

All Implemented Interfaces:

Closeable, AutoCloseable

public class MRJURLClassLoader
extends URLClassLoader

Polyfill for the URLClassLoader regarding the fact that classloaders can be named in Java 9 and beyond.

In Java 8 this doesn't do much, but in Java 9+ the classloader's name will show up in stacktraces, which is very helpful for diagnosing certain classloading errors.

This classloader is parallel-capable.

Constructor Summary

Constructors

Constructor	Description
MRJURLClassLoader(@NotNull String name, URL @NotNull [] urls, @Nullable ClassLoader parent)	Constructor.

Method Summary

Modifier and Type	Method	Description
static final @Nullable String	getClassloaderName(ClassLoader loader)	Returns the name of the given classloader.
@NotNull String	getName()	Obtains this classloader's name.
static final @Nullable ClassLoader	getPlatformClassLoader()	Obtains the platform classloader under Java 9 or above.

Methods inherited from class java.net.URLClassLoader

addURL, close, definePackage, findClass, findResource, findResources, getPermissions, getResourceAsStream, getURLs, newInstance, newInstance

Methods inherited from class java.security.SecureClassLoader

defineClass, defineClass

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findClass, findLibrary, findLoadedClass, findResource, findSystemClass, getClassLoadingLock, getDefinedPackage, getDefinedPackages, getPackage, getPackages, getParent, getResource, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, getUnnamedModule, isRegisteredAsParallelCapable, loadClass, loadClass, registerAsParallelCapable, resolveClass, resources, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners

Methods inherited from class java.lang.Object

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

Constructor Details

MRJURLClassLoader

public MRJURLClassLoader(@NotNull
 @NotNull String name,
 URL @NotNull [] urls,
 @Nullable
 @Nullable ClassLoader parent)

Constructor.

Parameters:

name - The name of the ClassLoader.

urls - The URLs for the URLClassLoader, see URLClassLoader.getURLs().

parent - The parent classloader, see ClassLoader.getParent().

Method Details

getClassloaderName

@Nullable
public static final @Nullable String getClassloaderName(ClassLoader loader)

Returns the name of the given classloader. For Java 8, this method only returns for classloaders that are an instance of MRJURLClassLoader. Otherwise, it returns null.

For Java 9 and above, it returns a value for any ClassLoader, provided said ClassLoader has been assigned a name.

Parameters:

loader - The ClassLoader instance to get the name of.

Returns:

The name of the given loader.

getPlatformClassLoader

@Nullable
public static final @Nullable ClassLoader getPlatformClassLoader()

Obtains the platform classloader under Java 9 or above. Under Java 8, null is returned.

Keep in mind that while the platform classloader contains the platform classes, it has also access to modules on the modulepath. This means that when using JPMS/Jigsaw, it may load classes that are part of the 'app' classloader. This behaviour contradicts the behaviour for classes present on the classpath, which cannot be loaded through the platform classloader.

Returns:

The platform classloader, if present.

getName

@NotNull
public @NotNull String getName()

Obtains this classloader's name.

Overrides:

getName in class ClassLoader

Returns:

The name of the classloader.