This method is invoked for the current security manager by the accept method of class ServerSocket.

This method calls checkPermission with the SocketPermission(host+":"+port,"accept") permission.

If you override this method, then you should make a call to super.checkAccept at the point the overridden method would normally throw an exception.
Parameters:
- host - the host name of the socket connection.
- port - the port number of the socket connection.
Throws:
- SecurityException - if the calling thread does not have permission to accept the connection.
- NullPointerException - if the host argument is null.
See Also: ServerSocket.accept(), checkPermission,

This method is invoked for the current security manager by the stop, suspend, resume, setPriority, setName, and setDaemon methods of class Thread.

If the thread argument is a system thread (belongs to the thread group with a null parent) then this method calls checkPermission with the RuntimePermission("modifyThread") permission. If the thread argument is not a system thread, this method just returns silently.

Applications that want a stricter policy should override this method. If this method is overridden, the method that overrides it should additionally check to see if the calling thread has the RuntimePermission("modifyThread") permission, and if so, return silently. This is to ensure that code granted that permission (such as the JDK itself) is allowed to manipulate any thread.

If this method is overridden, then super.checkAccess should be called by the first statement in the overridden method, or the equivalent security check should be placed in the overridden method.
Parameters:
- t - the thread to be checked.
Throws:
- SecurityException - if the calling thread does not have permission to modify the thread.
- NullPointerException - if the thread argument is null.
See Also: resume, setDaemon, setName, setPriority, stop, suspend, checkPermission,

This method is invoked for the current security manager when a new child thread or child thread group is created, and by the setDaemon, setMaxPriority, stop, suspend, resume, and destroy methods of class ThreadGroup.

If the thread group argument is the system thread group ( has a null parent) then this method calls checkPermission with the RuntimePermission("modifyThreadGroup") permission. If the thread group argument is not the system thread group, this method just returns silently.

Applications that want a stricter policy should override this method. If this method is overridden, the method that overrides it should additionally check to see if the calling thread has the RuntimePermission("modifyThreadGroup") permission, and if so, return silently. This is to ensure that code granted that permission (such as the JDK itself) is allowed to manipulate any thread.

If this method is overridden, then super.checkAccess should be called by the first statement in the overridden method, or the equivalent security check should be placed in the overridden method.
Parameters:
- g - the thread group to be checked.
Throws:
- SecurityException - if the calling thread does not have permission to modify the thread group.
- NullPointerException - if the thread group argument is null.
See Also: destroy, resume, setDaemon, setMaxPriority, stop, suspend, checkPermission,

This method calls checkPermission with the AWTPermission("accessEventQueue") permission.

If you override this method, then you should make a call to super.checkAwtEventQueueAccess at the point the overridden method would normally throw an exception.
Throws:
- SecurityException - if the calling thread does not have permission to access the AWT event queue.
Since: JDK1.1
See Also: checkPermission,

A port number of -1 indicates that the calling method is attempting to determine the IP address of the specified host name.

This method calls checkPermission with the SocketPermission(host+":"+port,"connect") permission if the port is not equal to -1. If the port is equal to -1, then it calls checkPermission with the SocketPermission(host,"resolve") permission.

If you override this method, then you should make a call to super.checkConnect at the point the overridden method would normally throw an exception.
Parameters:
- host - the host name port to connect to.
- port - the protocol port to connect to.
Throws:
- SecurityException - if the calling thread does not have permission to open a socket connection to the specified host and port.
- NullPointerException - if the host argument is null.
See Also: checkPermission,

A port number of -1 indicates that the calling method is attempting to determine the IP address of the specified host name.

If context is not an instance of AccessControlContext then a SecurityException is thrown.

Otherwise, the port number is checked. If it is not equal to -1, the context's checkPermission method is called with a SocketPermission(host+":"+port,"connect") permission. If the port is equal to -1, then the context's checkPermission method is called with a SocketPermission(host,"resolve") permission.

If you override this method, then you should make a call to super.checkConnect at the point the overridden method would normally throw an exception.
Parameters:
- host - the host name port to connect to.
- port - the protocol port to connect to.
- context - a system-dependent security context.
Throws:
- SecurityException - if the specified security context is not an instance of AccessControlContext (e.g., is null), or does not have permission to open a socket connection to the specified host and port.
- NullPointerException - if the host argument is null.
See Also: SecurityManager.getSecurityContext(), AccessControlContext.checkPermission(java.security.Permission),

This method calls checkPermission with the RuntimePermission("createClassLoader") permission.

If you override this method, then you should make a call to super.checkCreateClassLoader at the point the overridden method would normally throw an exception.
Throws:
- SecurityException - if the calling thread does not have permission to create a new class loader.
See Also: ClassLoader.ClassLoader(), checkPermission,

This method is invoked for the current security manager by the delete method of class File.

This method calls checkPermission with the FilePermission(file,"delete") permission.

If you override this method, then you should make a call to super.checkDelete at the point the overridden method would normally throw an exception.
Parameters:
- file - the system-dependent filename.
Throws:
- SecurityException - if the calling thread does not have permission to delete the file.
- NullPointerException - if the file argument is null.
See Also: File.delete(), checkPermission,

This method is invoked for the current security manager by the exec methods of class Runtime.

This method calls checkPermission with the FilePermission(cmd,"execute") permission if cmd is an absolute path, otherwise it calls checkPermission with FilePermission("<<ALL FILES>>","execute").

If you override this method, then you should make a call to super.checkExec at the point the overridden method would normally throw an exception.
Parameters:
- cmd - the specified system command.
Throws:
- SecurityException - if the calling thread does not have permission to create a subprocess.
- NullPointerException - if the cmd argument is null.
See Also: Runtime.exec(java.lang.String), Runtime.exec(java.lang.String, java.lang.String[]), Runtime.exec(java.lang.String[]), Runtime.exec(java.lang.String[], java.lang.String[]), checkPermission,

This method is invoked for the current security manager by the exit method of class Runtime. A status of 0 indicates success; other values indicate various errors.

This method calls checkPermission with the RuntimePermission("exitVM."+status) permission.

If you override this method, then you should make a call to super.checkExit at the point the overridden method would normally throw an exception.
Parameters:
- status - the exit status.
Throws:
- SecurityException - if the calling thread does not have permission to halt the Java Virtual Machine with the specified status.
See Also: exit, checkPermission,

This method is invoked for the current security manager by methods load and loadLibrary of class Runtime.

This method calls checkPermission with the RuntimePermission("loadLibrary."+lib) permission.

If you override this method, then you should make a call to super.checkLink at the point the overridden method would normally throw an exception.
Parameters:
- lib - the name of the library.
Throws:
- SecurityException - if the calling thread does not have permission to dynamically link the library.
- NullPointerException - if the lib argument is null.
See Also: Runtime.load(java.lang.String), Runtime.loadLibrary(java.lang.String), checkPermission,

If port is not 0, this method calls checkPermission with the SocketPermission("localhost:"+port,"listen"). If port is zero, this method calls checkPermission with SocketPermission("localhost:1024-","listen").

If you override this method, then you should make a call to super.checkListen at the point the overridden method would normally throw an exception.
Parameters:
- port - the local port.
Throws:
- SecurityException - if the calling thread does not have permission to listen on the specified port.
See Also: checkPermission,

The default policy is to allow access to PUBLIC members, as well as access to classes that have the same class loader as the caller. In all other cases, this method calls checkPermission with the RuntimePermission("accessDeclaredMembers") permission.

If this method is overridden, then a call to super.checkMemberAccess cannot be made, as the default implementation of checkMemberAccess relies on the code being checked being at a stack depth of 4.
Parameters:
- clazz - the class that reflection is to be performed on.
- which - type of access, PUBLIC or DECLARED.
Throws:
- SecurityException - if the caller does not have permission to access members.
- NullPointerException - if the clazz argument is null.
Since: JDK1.1
See Also: Member, checkPermission,

This method calls checkPermission with the java.net.SocketPermission(maddr.getHostAddress(), "accept,connect") permission.

If you override this method, then you should make a call to super.checkMulticast at the point the overridden method would normally throw an exception.
Parameters:
- maddr - Internet group address to be used.
Throws:
- SecurityException - if the calling thread is not allowed to use (join/leave/send/receive) IP multicast.
- NullPointerException - if the address argument is null.
Since: JDK1.1
See Also: checkPermission,

This method calls checkPermission with the java.net.SocketPermission(maddr.getHostAddress(), "accept,connect") permission.

If you override this method, then you should make a call to super.checkMulticast at the point the overridden method would normally throw an exception.
Parameters:
- maddr - Internet group address to be used.
- ttl - value in use, if it is multicast send. Note: this particular implementation does not use the ttl parameter.
Throws:
- SecurityException - if the calling thread is not allowed to use (join/leave/send/receive) IP multicast.
- NullPointerException - if the address argument is null.
Since: JDK1.1
See Also: checkPermission,

This method is used by the loadClass method of class loaders.

This method first gets a list of restricted packages by obtaining a comma-separated list from a call to java.security.Security.getProperty("package.access"), and checks to see if pkg starts with or equals any of the restricted packages. If it does, then checkPermission gets called with the RuntimePermission("accessClassInPackage."+pkg) permission.

If this method is overridden, then super.checkPackageAccess should be called as the first line in the overridden method.
Parameters:
- pkg - the package name.
Throws:
- SecurityException - if the calling thread does not have permission to access the specified package.
- NullPointerException - if the package name argument is null.
See Also: loadClass, getProperty, checkPermission,

This method is used by the loadClass method of some class loaders.

This method first gets a list of restricted packages by obtaining a comma-separated list from a call to java.security.Security.getProperty("package.definition"), and checks to see if pkg starts with or equals any of the restricted packages. If it does, then checkPermission gets called with the RuntimePermission("defineClassInPackage."+pkg) permission.

If this method is overridden, then super.checkPackageDefinition should be called as the first line in the overridden method.
Parameters:
- pkg - the package name.
Throws:
- SecurityException - if the calling thread does not have permission to define classes in the specified package.
See Also: ClassLoader.loadClass(java.lang.String, boolean), getProperty, checkPermission,

This method calls AccessController.checkPermission with the given permission.
Parameters:
- perm - the requested permission.
Throws:
- SecurityException - if access is not permitted based on the current security policy.
- NullPointerException - if the permission argument is null.
Since: 1.2

If context is an instance of AccessControlContext then the AccessControlContext.checkPermission method is invoked with the specified permission.

If context is not an instance of AccessControlContext then a SecurityException is thrown.
Parameters:
- perm - the specified permission
- context - a system-dependent security context.
Throws:
- SecurityException - if the specified security context is not an instance of AccessControlContext (e.g., is null), or is denied access to the resource specified by the given permission.
- NullPointerException - if the permission argument is null.
Since: 1.2
See Also: SecurityManager.getSecurityContext(), AccessControlContext.checkPermission(java.security.Permission),

This method calls checkPermission with the RuntimePermission("queuePrintJob") permission.

If you override this method, then you should make a call to super.checkPrintJobAccess at the point the overridden method would normally throw an exception.

Throws:
- SecurityException - if the calling thread does not have permission to initiate a print job request.
Since: JDK1.1
See Also: checkPermission,

This method is used by the getProperties and setProperties methods of class System.

This method calls checkPermission with the PropertyPermission("*", "read,write") permission.

If you override this method, then you should make a call to super.checkPropertiesAccess at the point the overridden method would normally throw an exception.

Throws:
- SecurityException - if the calling thread does not have permission to access or modify the system properties.
See Also: System.getProperties(), System.setProperties(java.util.Properties), checkPermission,

This method is used by the getProperty method of class System.

This method calls checkPermission with the PropertyPermission(key, "read") permission.

If you override this method, then you should make a call to super.checkPropertyAccess at the point the overridden method would normally throw an exception.
Parameters:
- key - a system property key.
Throws:
- SecurityException - if the calling thread does not have permission to access the specified system property.
- NullPointerException - if the key argument is null.
- IllegalArgumentException - if key is empty.
See Also: System.getProperty(java.lang.String), checkPermission,

This method calls checkPermission with the RuntimePermission("readFileDescriptor") permission.

If you override this method, then you should make a call to super.checkRead at the point the overridden method would normally throw an exception.
Parameters:
- fd - the system-dependent file descriptor.
Throws:
- SecurityException - if the calling thread does not have permission to access the specified file descriptor.
- NullPointerException - if the file descriptor argument is null.
See Also: FileDescriptor, checkPermission,

This method calls checkPermission with the FilePermission(file,"read") permission.

If you override this method, then you should make a call to super.checkRead at the point the overridden method would normally throw an exception.
Parameters:
- file - the system-dependent file name.
Throws:
- SecurityException - if the calling thread does not have permission to access the specified file.
- NullPointerException - if the file argument is null.
See Also: checkPermission,

If context is an instance of AccessControlContext then the AccessControlContext.checkPermission method will be invoked with the FilePermission(file,"read") permission.

If context is not an instance of AccessControlContext then a SecurityException is thrown.

If you override this method, then you should make a call to super.checkRead at the point the overridden method would normally throw an exception.
Parameters:
- file - the system-dependent filename.
- context - a system-dependent security context.
Throws:
- SecurityException - if the specified security context is not an instance of AccessControlContext (e.g., is null), or does not have permission to read the specified file.
- NullPointerException - if the file argument is null.
See Also: SecurityManager.getSecurityContext(), AccessControlContext.checkPermission(java.security.Permission),

If the requested permission is allowed, this method returns quietly. If denied, a SecurityException is raised.

This method creates a SecurityPermission object for the given permission target name and calls checkPermission with it.

See the documentation for SecurityPermission for a list of possible permission target names.

If you override this method, then you should make a call to super.checkSecurityAccess at the point the overridden method would normally throw an exception.
Parameters:
- target - the target name of the SecurityPermission.
Throws:
- SecurityException - if the calling thread does not have permission for the requested access.
- NullPointerException - if target is null.
- IllegalArgumentException - if target is empty.
Since: JDK1.1
See Also: checkPermission,

This method calls checkPermission with the RuntimePermission("setFactory") permission.

If you override this method, then you should make a call to super.checkSetFactory at the point the overridden method would normally throw an exception.

Throws:
- SecurityException - if the calling thread does not have permission to specify a socket factory or a stream handler factory.
See Also: setSocketFactory, setSocketImplFactory, setURLStreamHandlerFactory, checkPermission,

This method calls checkPermission with the AWTPermission("accessClipboard") permission.

If you override this method, then you should make a call to super.checkSystemClipboardAccess at the point the overridden method would normally throw an exception.
Throws:
- SecurityException - if the calling thread does not have permission to access the system clipboard.
Since: JDK1.1
See Also: checkPermission,

See class Window for more information on trusted and untrusted windows.

This method calls checkPermission with the AWTPermission("showWindowWithoutWarningBanner") permission, and returns true if a SecurityException is not thrown, otherwise it returns false.

If you override this method, then you should make a call to super.checkTopLevelWindow at the point the overridden method would normally return false, and the value of super.checkTopLevelWindow should be returned.
Returns: true if the calling thread is trusted to put up top-level windows; false otherwise.
Parameters:
- window - the new window that is being created.
Throws:
- NullPointerException - if the window argument is null.
See Also: Window, checkPermission,

This method calls checkPermission with the RuntimePermission("writeFileDescriptor") permission.

If you override this method, then you should make a call to super.checkWrite at the point the overridden method would normally throw an exception.
Parameters:
- fd - the system-dependent file descriptor.
Throws:
- SecurityException - if the calling thread does not have permission to access the specified file descriptor.
- NullPointerException - if the file descriptor argument is null.
See Also: FileDescriptor, checkPermission,

This method calls checkPermission with the FilePermission(file,"write") permission.

If you override this method, then you should make a call to super.checkWrite at the point the overridden method would normally throw an exception.
Parameters:
- file - the system-dependent filename.
Throws:
- SecurityException - if the calling thread does not have permission to access the specified file.
- NullPointerException - if the file argument is null.
See Also: checkPermission,

This method will return -1 in the following three cases:

1. All methods on the execution stack are from classes defined using the system class loader or one of its ancestors.
2. All methods on the execution stack up to the first "privileged" caller (see AccessController.doPrivileged(java.security.PrivilegedAction)) are from classes defined using the system class loader or one of its ancestors.
3. A call to checkPermission with java.security.AllPermission does not result in a SecurityException.

This method will return null in the following three cases:

1. All methods on the execution stack are from classes defined using the system class loader or one of its ancestors.
2. All methods on the execution stack up to the first "privileged" caller (see AccessController.doPrivileged(java.security.PrivilegedAction)) are from classes defined using the system class loader or one of its ancestors.
3. A call to checkPermission with java.security.AllPermission does not result in a SecurityException.

This method will return null in the following three cases:

1. All methods on the execution stack are from classes defined using the system class loader or one of its ancestors.
2. All methods on the execution stack up to the first "privileged" caller (see AccessController.doPrivileged(java.security.PrivilegedAction)) are from classes defined using the system class loader or one of its ancestors.
3. A call to checkPermission with java.security.AllPermission does not result in a SecurityException.

The length of the array is the number of methods on the execution stack. The element at index 0 is the class of the currently executing method, the element at index 1 is the class of that method's caller, and so on.
Returns: the execution stack.

The default implementation of this method is to return an AccessControlContext object.
Returns: an implementation-dependent object that encapsulates sufficient information about the current execution environment to perform some security checks later.
See Also: checkConnect, checkRead, AccessControlContext,