Added in API level 1

URLClassLoader

open class URLClassLoader : SecureClassLoader, Closeable

kotlin.Any
↳	java.lang.ClassLoader
	↳	java.security.SecureClassLoader
		↳	java.net.URLClassLoader

This class loader is used to load classes and resources from a search path of URLs referring to both JAR files and directories. Any URL that ends with a '/' is assumed to refer to a directory. Otherwise, the URL is assumed to refer to a JAR file which will be opened as needed.

The AccessControlContext of the thread that created the instance of URLClassLoader will be used when subsequently loading classes and resources.

The classes that are loaded are by default granted permission only to access the URLs specified when the URLClassLoader was created.

Summary

Public constructors
URLClassLoader(urls: Array<URL!>!) Constructs a new URLClassLoader for the specified URLs using the default delegation parent ClassLoader.
URLClassLoader(urls: Array<URL!>!, parent: ClassLoader!) Constructs a new URLClassLoader for the given URLs.
URLClassLoader(urls: Array<URL!>!, parent: ClassLoader!, factory: URLStreamHandlerFactory!) Constructs a new URLClassLoader for the specified URLs, parent class loader, and URLStreamHandlerFactory.

Public methods
open Unit	close() Closes this URLClassLoader, so that it can no longer be used to load new classes or resources that are defined by this loader.
open URL!	findResource(name: String!) Finds the resource with the specified name on the URL search path.
open Enumeration<URL!>!	findResources(name: String!) Returns an Enumeration of URLs representing all of the resources on the URL search path having the specified name.
open InputStream!	getResourceAsStream(name: String!) Returns an input stream for reading the specified resource.
open Array<URL!>!	getURLs() Returns the search path of URLs for loading classes and resources.
open static URLClassLoader!	newInstance(urls: Array<URL!>!) Creates a new instance of URLClassLoader for the specified URLs and default parent class loader.
open static URLClassLoader!	newInstance(urls: Array<URL!>!, parent: ClassLoader!) Creates a new instance of URLClassLoader for the specified URLs and parent class loader.

Protected methods
open Unit	addURL(url: URL!) Appends the specified URL to the list of URLs to search for classes and resources.
open Package!	definePackage(name: String!, man: Manifest!, url: URL!) Defines a new package by name in this ClassLoader.
open Class<*>!	findClass(name: String!) Finds and loads the class with the specified name from the URL search path.
open PermissionCollection!	getPermissions(codesource: CodeSource!) Returns the permissions for the given codesource object.

Inherited functions
From class ClassLoader Unit clearAssertionStatus() Sets the default assertion status for this class loader to false and discards any package defaults or class assertion status settings associated with the class loader. This method is provided so that class loaders can be made to ignore any command line or persistent assertion status settings and "start with a clean slate." Android-note: AssertionStatuses are unsupported. This method is a no-op. Class<*>! defineClass(b: ByteArray!, off: Int, len: Int) Converts an array of bytes into an instance of class Class. Before the Class can be used it must be resolved. This method is deprecated in favor of the version that takes a binary name as its first argument, and is more secure. Class<*>! defineClass(name: String!, b: ByteArray!, off: Int, len: Int) Converts an array of bytes into an instance of class Class. Before the Class can be used it must be resolved. This method assigns a default ProtectionDomain to the newly defined class. The ProtectionDomain is effectively granted the same set of permissions returned when Policy.getPolicy().getPermissions(new CodeSource(null, null)) is invoked. The default protection domain is created on the first invocation of defineClass, and re-used on subsequent invocations. To assign a specific ProtectionDomain to the class, use the defineClass method that takes a ProtectionDomain as one of its arguments. This method defines a package in this class loader corresponding to the package of the Class (if such a package has not already been defined in this class loader). The name of the defined package is derived from the binary name of the class specified by the byte array b. Other properties of the defined package are as specified by Package. Class<*>! defineClass(name: String!, b: ByteArray!, off: Int, len: Int, protectionDomain: ProtectionDomain!) Converts an array of bytes into an instance of class Class, with a given ProtectionDomain. If the given ProtectionDomain is null, then a default protection domain will be assigned to the class as specified in the documentation for defineClass(java.lang.String,byte[],int,int). Before the class can be used it must be resolved. The first class defined in a package determines the exact set of certificates that all subsequent classes defined in that package must contain. The set of certificates for a class is obtained from the CodeSource within the ProtectionDomain of the class. Any classes added to that package must contain the same set of certificates or a SecurityException will be thrown. Note that if name is null, this check is not performed. You should always pass in the binary name of the class you are defining as well as the bytes. This ensures that the class you are defining is indeed the class you think it is. This method defines a package in this class loader corresponding to the package of the Class (if such a package has not already been defined in this class loader). The name of the defined package is derived from the binary name of the class specified by the byte array b. Other properties of the defined package are as specified by Package. Class<*>! defineClass(name: String!, b: ByteBuffer!, protectionDomain: ProtectionDomain!) Converts a ByteBuffer into an instance of class Class, with the given ProtectionDomain. If the given ProtectionDomain is null, then a default protection domain will be assigned to the class as specified in the documentation for defineClass(java.lang.String,byte[],int,int). Before the class can be used it must be resolved. The rules about the first class defined in a package determining the set of certificates for the package, the restrictions on class names, and the defined package of the class are identical to those specified in the documentation for defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain). An invocation of this method of the form cl.defineClass(name, bBuffer, pd) yields exactly the same result as the statements ... byte[] temp = new byte[bBuffer.remaining()]; bBuffer. get(temp); return cl.defineClass(name, temp, 0, temp.length, pd); Package! definePackage(name: String!, specTitle: String!, specVersion: String!, specVendor: String!, implTitle: String!, implVersion: String!, implVendor: String!, sealBase: URL!) Defines a package by name in this ClassLoader. Package names must be unique within a class loader and cannot be redefined or changed once created. If a class loader wishes to define a package with specific properties, such as version information, then the class loader should call this definePackage method before calling defineClass. Otherwise, the defineClass method will define a package in this class loader corresponding to the package of the newly defined class; the properties of this defined package are specified by Package. Class<*>! findClass(name: String!) Finds the class with the specified binary name. This method should be overridden by class loader implementations that follow the delegation model for loading classes, and will be invoked by the #loadClass method after checking the parent class loader for the requested class. String! findLibrary(libname: String!) Returns the absolute path name of a native library. The VM invokes this method to locate the native libraries that belong to classes loaded with this class loader. If this method returns null, the VM searches the library along the path specified as the "java.library.path" property. Class<*>! findLoadedClass(name: String!) Returns the class with the given binary name if this loader has been recorded by the Java virtual machine as an initiating loader of a class with that binary name. Otherwise null is returned. URL! findResource(name: String!) Finds the resource with the given name. Class loader implementations should override this method. Enumeration<URL!>! findResources(name: String!) Returns an enumeration of URL objects representing all the resources with the given name. Class loader implementations should override this method. Class<*>! findSystemClass(name: String!) Finds a class with the specified binary name, loading it if necessary. This method loads the class through the system class loader (see getSystemClassLoader()). The Class object returned might have more than one ClassLoader associated with it. Subclasses of ClassLoader need not usually invoke this method, because most class loaders need to override just findClass(java.lang.String). Package! getPackage(name: String!) Finds a package by name in this class loader and its ancestors. If this class loader defines a Package of the given name, the Package is returned. Otherwise, the ancestors of this class loader are searched recursively (parent by parent) for a Package of the given name. Array<Package!>! getPackages() Returns all of the Packages that have been defined by this class loader and its ancestors. The returned array may contain more than one Package object of the same package name, each defined by a different class loader in the class loader hierarchy. ClassLoader! getParent() Returns the parent class loader for delegation. Some implementations may use null to represent the bootstrap class loader. This method will return null in such implementations if this class loader's parent is the bootstrap class loader. URL! getResource(name: String!) Finds the resource with the given name. A resource is some data (images, audio, text, etc) that can be accessed by class code in a way that is independent of the location of the code. The name of a resource is a '/'-separated path name thatf identifies the resource. InputStream! getResourceAsStream(name: String!) Returns an input stream for reading the specified resource. The search order is described in the documentation for getResource(java.lang.String). Enumeration<URL!>! getResources(name: String!) Finds all the resources with the given name. A resource is some data (images, audio, text, etc) that can be accessed by class code in a way that is independent of the location of the code. The name of a resource is a /-separated path name that identifies the resource. ClassLoader! getSystemClassLoader() Returns the system class loader. This is the default delegation parent for new ClassLoader instances, and is typically the class loader used to start the application. This method is first invoked early in the runtime's startup sequence, at which point it creates the system class loader. This class loader will be the context class loader for the main application thread (for example, the thread that invokes the main method of the main class). The default system class loader is an implementation-dependent instance of this class. URL! getSystemResource(name: String!) Find a resource of the specified name from the search path used to load classes. This method locates the resource through the system class loader (see getSystemClassLoader()). InputStream! getSystemResourceAsStream(name: String!) Open for reading, a resource of the specified name from the search path used to load classes. This method locates the resource through the system class loader (see getSystemClassLoader()). Enumeration<URL!>! getSystemResources(name: String!) Finds all resources of the specified name from the search path used to load classes. The resources thus found are returned as an Enumeration of objects. The search order is described in the documentation for getSystemResource(java.lang.String). Class<*>! loadClass(name: String!) Loads the class with the specified binary name. This method searches for classes in the same manner as the loadClass(java.lang.String,boolean) method. It is invoked by the Java virtual machine to resolve class references. Invoking this method is equivalent to invoking loadClass(name,. Class<*>! loadClass(name: String!, resolve: Boolean) Loads the class with the specified binary name. The default implementation of this method searches for classes in the following order: Invoke findLoadedClass(java.lang.String) to check if the class has already been loaded. Invoke the loadClass method on the parent class loader. If the parent is null the class loader built into the virtual machine is used, instead. Invoke the findClass(java.lang.String) method to find the class. If the class was found using the above steps, and the resolve flag is true, this method will then invoke the resolveClass(java.lang.Class) method on the resulting Class object. Subclasses of ClassLoader are encouraged to override findClass(java.lang.String), rather than this method. Boolean registerAsParallelCapable() Registers the caller as isRegisteredAsParallelCapable() parallel capable. The registration succeeds if and only if all of the following conditions are met: no instance of the caller has been created all of the super classes (except class Object) of the caller are registered as parallel capable Note that once a class loader is registered as parallel capable, there is no way to change it back. Unit resolveClass(c: Class<*>!) Links the specified class. This (misleadingly named) method may be used by a class loader to link a class. If the class c has already been linked, then this method simply returns. Otherwise, the class is linked as described in the "Execution" chapter of The Java Language Specification. Unit setClassAssertionStatus(className: String!, enabled: Boolean) Sets the desired assertion status for the named top-level class in this class loader and any nested classes contained therein. This setting takes precedence over the class loader's default assertion status, and over any applicable per-package default. This method has no effect if the named class has already been initialized. (Once a class is initialized, its assertion status cannot change.) If the named class is not a top-level class, this invocation will have no effect on the actual assertion status of any class. Android-note: AssertionStatuses are unsupported. This method is a no-op. Unit setDefaultAssertionStatus(enabled: Boolean) Sets the default assertion status for this class loader. This setting determines whether classes loaded by this class loader and initialized in the future will have assertions enabled or disabled by default. This setting may be overridden on a per-package or per-class basis by invoking setPackageAssertionStatus(java.lang.String,boolean) or setClassAssertionStatus(java.lang.String,boolean). Android-note: AssertionStatuses are unsupported. This method is a no-op. Unit setPackageAssertionStatus(packageName: String!, enabled: Boolean) Sets the package default assertion status for the named package. The package default assertion status determines the assertion status for classes initialized in the future that belong to the named package or any of its "subpackages". A subpackage of a package named p is any package whose name begins with "p.". For example, javax.swing.text is a subpackage of javax.swing, and both java.util and java.lang.reflect are subpackages of java. In the event that multiple package defaults apply to a given class, the package default pertaining to the most specific package takes precedence over the others. For example, if javax.lang and javax.lang.reflect both have package defaults associated with them, the latter package default applies to classes in javax.lang.reflect. Package defaults take precedence over the class loader's default assertion status, and may be overridden on a per-class basis by invoking setClassAssertionStatus(java.lang.String,boolean). Android-note: AssertionStatuses are unsupported. This method is a no-op. Unit setSigners(c: Class<*>!, signers: Array<Any!>!) Sets the signers of a class. This should be invoked after defining a class.
From class SecureClassLoader Class<*>! defineClass(name: String!, b: ByteArray!, off: Int, len: Int, cs: CodeSource!) Converts an array of bytes into an instance of class Class, with an optional CodeSource. Before the class can be used it must be resolved. If a non-null CodeSource is supplied a ProtectionDomain is constructed and associated with the class being defined. Class<*>! defineClass(name: String!, b: ByteBuffer!, cs: CodeSource!) Converts a ByteBuffer into an instance of class Class, with an optional CodeSource. Before the class can be used it must be resolved. If a non-null CodeSource is supplied a ProtectionDomain is constructed and associated with the class being defined.

Public constructors

URLClassLoader

Added in API level 1

URLClassLoader(urls: Array<URL!>!)

Constructs a new URLClassLoader for the specified URLs using the default delegation parent ClassLoader. The URLs will be searched in the order specified for classes and resources after first searching in the parent class loader. Any URL that ends with a '/' is assumed to refer to a directory. Otherwise, the URL is assumed to refer to a JAR file which will be downloaded and opened as needed.

If there is a security manager, this method first calls the security manager's checkCreateClassLoader method to ensure creation of a class loader is allowed.

Parameters
urls	Array<URL!>!: the URLs from which to load classes and resources

Exceptions
java.lang.SecurityException	if a security manager exists and its checkCreateClassLoader method doesn't allow creation of a class loader.
java.lang.NullPointerException	if urls is null.

See Also

• java.lang.SecurityManager#checkCreateClassLoader

URLClassLoader

Added in API level 1

URLClassLoader(
    urls: Array<URL!>!, 
    parent: ClassLoader!)

Constructs a new URLClassLoader for the given URLs. The URLs will be searched in the order specified for classes and resources after first searching in the specified parent class loader. Any URL that ends with a '/' is assumed to refer to a directory. Otherwise, the URL is assumed to refer to a JAR file which will be downloaded and opened as needed.

If there is a security manager, this method first calls the security manager's checkCreateClassLoader method to ensure creation of a class loader is allowed.

Parameters
urls	Array<URL!>!: the URLs from which to load classes and resources
parent	ClassLoader!: the parent class loader for delegation

Exceptions
java.lang.SecurityException	if a security manager exists and its checkCreateClassLoader method doesn't allow creation of a class loader.
java.lang.NullPointerException	if urls is null.

See Also

• java.lang.SecurityManager#checkCreateClassLoader

URLClassLoader

Added in API level 1

URLClassLoader(
    urls: Array<URL!>!, 
    parent: ClassLoader!, 
    factory: URLStreamHandlerFactory!)

Constructs a new URLClassLoader for the specified URLs, parent class loader, and URLStreamHandlerFactory. The parent argument will be used as the parent class loader for delegation. The factory argument will be used as the stream handler factory to obtain protocol handlers when creating new jar URLs.

If there is a security manager, this method first calls the security manager's checkCreateClassLoader method to ensure creation of a class loader is allowed.

Parameters
urls	Array<URL!>!: the URLs from which to load classes and resources
parent	ClassLoader!: the parent class loader for delegation
factory	URLStreamHandlerFactory!: the URLStreamHandlerFactory to use when creating URLs

Exceptions
java.lang.SecurityException	if a security manager exists and its checkCreateClassLoader method doesn't allow creation of a class loader.
java.lang.NullPointerException	if urls is null.

See Also

• java.lang.SecurityManager#checkCreateClassLoader

Public methods

close

Added in API level 24

open fun close(): Unit

Closes this URLClassLoader, so that it can no longer be used to load new classes or resources that are defined by this loader. Classes and resources defined by any of this loader's parents in the delegation hierarchy are still accessible. Also, any classes or resources that are already loaded, are still accessible.

In the case of jar: and file: URLs, it also closes any files that were opened by it. If another thread is loading a class when the close method is invoked, then the result of that load is undefined.

The method makes a best effort attempt to close all opened files, by catching IOExceptions internally. Unchecked exceptions and errors are not caught. Calling close on an already closed loader has no effect.

Exceptions
java.lang.Exception	if this resource cannot be closed
java.io.IOException	if an I/O error occurs
java.io.IOException	if closing any file opened by this class loader resulted in an IOException. Any such exceptions are caught internally. If only one is caught, then it is re-thrown. If more than one exception is caught, then the second and following exceptions are added as suppressed exceptions of the first one caught, which is then re-thrown.
java.lang.SecurityException	if a security manager is set, and it denies RuntimePermission("closeClassLoader")

findResource

Added in API level 1

open fun findResource(name: String!): URL!

Finds the resource with the specified name on the URL search path.

Parameters
name	String!: the name of the resource

Return
URL!	a URL for the resource, or null if the resource could not be found, or if the loader is closed.

findResources

Added in API level 1

open fun findResources(name: String!): Enumeration<URL!>!

Returns an Enumeration of URLs representing all of the resources on the URL search path having the specified name.

Parameters
name	String!: the resource name

Return
Enumeration<URL!>!	an Enumeration of URLs If the loader is closed, the Enumeration will be empty.

Exceptions
java.io.IOException	If I/O errors occur
java.io.IOException	if an I/O exception occurs

getResourceAsStream

Added in API level 1

open fun getResourceAsStream(name: String!): InputStream!

Returns an input stream for reading the specified resource. If this loader is closed, then any resources opened by this method will be closed.

The search order is described in the documentation for getResource(java.lang.String).

Parameters
name	String!: The resource name

Return
InputStream!	An input stream for reading the resource, or null if the resource could not be found

Exceptions
java.lang.NullPointerException	If name is null

getURLs

Added in API level 1

open fun getURLs(): Array<URL!>!

Returns the search path of URLs for loading classes and resources. This includes the original list of URLs specified to the constructor, along with any URLs subsequently appended by the addURL() method.

Return
Array<URL!>!	the search path of URLs for loading classes and resources.

newInstance

Added in API level 1

open static fun newInstance(urls: Array<URL!>!): URLClassLoader!

Creates a new instance of URLClassLoader for the specified URLs and default parent class loader. If a security manager is installed, the loadClass method of the URLClassLoader returned by this method will invoke the SecurityManager.checkPackageAccess before loading the class.

Parameters
urls	Array<URL!>!: the URLs to search for classes and resources

Return
URLClassLoader!	the resulting class loader

Exceptions
java.lang.NullPointerException	if urls is null.

newInstance

Added in API level 1

open static fun newInstance(
    urls: Array<URL!>!, 
    parent: ClassLoader!
): URLClassLoader!

Creates a new instance of URLClassLoader for the specified URLs and parent class loader. If a security manager is installed, the loadClass method of the URLClassLoader returned by this method will invoke the SecurityManager.checkPackageAccess method before loading the class.

Parameters
urls	Array<URL!>!: the URLs to search for classes and resources
parent	ClassLoader!: the parent class loader for delegation

Return
URLClassLoader!	the resulting class loader

Exceptions
java.lang.NullPointerException	if urls is null.

Protected methods

addURL

Added in API level 1

protected open fun addURL(url: URL!): Unit

Appends the specified URL to the list of URLs to search for classes and resources.

If the URL specified is null or is already in the list of URLs, or if this loader is closed, then invoking this method has no effect.

Parameters
url	URL!: the URL to be added to the search path of URLs

definePackage

Added in API level 1

protected open fun definePackage(
    name: String!, 
    man: Manifest!, 
    url: URL!
): Package!

Defines a new package by name in this ClassLoader. The attributes contained in the specified Manifest will be used to obtain package version and sealing information. For sealed packages, the additional URL specifies the code source URL from which the package was loaded.

Parameters
name	String!: the package name
man	Manifest!: the Manifest containing package version and sealing information
url	URL!: the code source url for the package, or null if none

Return
Package!	the newly defined Package object

Exceptions
java.lang.IllegalArgumentException	if the package name duplicates an existing package either in this class loader or one of its ancestors

findClass

Added in API level 1

protected open fun findClass(name: String!): Class<*>!

Finds and loads the class with the specified name from the URL search path. Any URLs referring to JAR files are loaded and opened as needed until the class is found.

Parameters
name	String!: the name of the class

Return
Class<*>!	the resulting class

Exceptions
java.lang.ClassNotFoundException	If the class could not be found
java.lang.ClassNotFoundException	if the class could not be found, or if the loader is closed.
java.lang.NullPointerException	if name is null.

getPermissions

Added in API level 1

protected open fun getPermissions(codesource: CodeSource!): PermissionCollection!

Returns the permissions for the given codesource object. The implementation of this method first calls super.getPermissions and then adds permissions based on the URL of the codesource.

If the protocol of this URL is "jar", then the permission granted is based on the permission that is required by the URL of the Jar file.

If the protocol is "file" and there is an authority component, then permission to connect to and accept connections from that authority may be granted. If the protocol is "file" and the path specifies a file, then permission to read that file is granted. If protocol is "file" and the path is a directory, permission is granted to read all files and (recursively) all files and subdirectories contained in that directory.

If the protocol is not "file", then permission to connect to and accept connections from the URL's host is granted.

Parameters
codesource	CodeSource!: the codesource

Return
PermissionCollection!	the permissions granted to the codesource

Exceptions
java.lang.NullPointerException	if codesource is null.