OpenJDK 27 · java.security.Permission · APIdia, the JavaDoc alternative

Abstract class for representing access to a system resource. All permissions have a name (whose interpretation depends on the subclass), as well as abstract functions for defining the semantics of the particular Permission subclass.

Most Permission objects also include an "actions" list that tells the actions that are permitted for the object. For example, for a java.io.FilePermission object, the permission name is the pathname of a file (or directory), and the actions list (such as "read, write") specifies which actions are granted for the specified file (or for files in the specified directory). The actions list is optional for Permission objects, such as java.lang.RuntimePermission, that don't need such a list; you either have the named permission (such as "system.exit") or you don't.

An important method that must be implemented by each subclass is the implies method to compare Permissions. Basically, "permission p1 implies permission p2" means that if one is granted permission p1, one is naturally granted permission p2. Thus, this is not an equality test, but rather more of a subset test.

Permission objects are similar to String objects in that they are immutable once they have been created. Subclasses should not provide methods that can change the state of a permission once it has been created.

Modifier and Type	Field and Description
private final String	name
private static final long	serialVersionUID

Constructor Summary

Access	Constructor and Description
public	Permission(String name of the `Permission` object being created. name) Constructs a permission with the specified name.

Method Summary

Modifier and Type	Method and Description
public void	checkGuard(Object the object being guarded (currently ignored). object) Implements java.security.Guard.checkGuard. Implements the guard interface for a permission.
public abstract boolean	Returns: `true` if both `Permission` objects are equivalent. equals(Object the object we are testing for equality with this object. obj) Overrides java.lang.Object.equals. Checks two `Permission` objects for equality.
public abstract String	Returns: the actions of this `Permission`. getActions() Returns the actions as a `String`.
public final String	Returns: the name of this `Permission`. getName() Returns the name of this `Permission`.
public abstract int	Returns: a hash code value for this object. hashCode() Overrides java.lang.Object.hashCode. Returns the hash code value for this `Permission` object.
public abstract boolean	Returns: `true` if the specified permission is implied by this object, `false` if not. implies(Permission the permission to check against. permission) Checks if the specified permission's actions are "implied by" this object's actions.
public PermissionCollection	Returns: a new `PermissionCollection` object for this type of `Permission`, or `null` if one is not defined. newPermissionCollection() Returns an empty `PermissionCollection` for a given `Permission` object, or `null` if one is not defined.
public String	Returns: information about this `Permission`. toString() Overrides java.lang.Object.toString. Returns a string describing this `Permission`.

Inherited from java.lang.Object:: clone finalize getClass notify notifyAll wait wait wait

Field Detail

name	back to summary
private final String name

serialVersionUID	back to summary
private static final long serialVersionUID Annotations @Serial

Constructor Detail

Permission back to summary

Permission	back to summary
public Permission(String name) Constructs a permission with the specified name. Parameters name:String name of the `Permission` object being created.

public Permission(String name)

Constructs a permission with the specified name.

Parameters

name:String: name of the Permission object being created.

Method Detail

checkGuard back to summary

checkGuard	back to summary
public void checkGuard(Object object) throws SecurityException Implements java.security.Guard.checkGuard. Implements the guard interface for a permission. Returns silently if access is granted. Otherwise, throws a `SecurityException`. API Note This method originally threw a `SecurityException` if a security manager was enabled and the requested access, specified by this permission, was not permitted. The Security Manager is no longer supported; thus, this method always throws a `SecurityException`. Parameters object:Object the object being guarded (currently ignored). Annotations @Override Exceptions SecurityException: always See Also `Guard`, `GuardedObject`

public void checkGuard(Object object) throws SecurityException

Implements java.security.Guard.checkGuard.

Implements the guard interface for a permission. Returns silently if access is granted. Otherwise, throws a SecurityException.

API Note

This method originally threw a SecurityException if a security manager was enabled and the requested access, specified by this permission, was not permitted. The Security Manager is no longer supported; thus, this method always throws a SecurityException.

Parameters

object:Object: the object being guarded (currently ignored).

Annotations

@Override

Exceptions

SecurityException:: always

See Also

Guard, GuardedObject

equals back to summary

equals	back to summary
public abstract boolean equals(Object obj) Overrides java.lang.Object.equals. Checks two `Permission` objects for equality. Do not use the `equals` method for making access control decisions; use the `implies` method. Parameters obj:Object the object we are testing for equality with this object. Returns:boolean `true` if both `Permission` objects are equivalent. Annotations @Override

public abstract boolean equals(Object obj)

Overrides java.lang.Object.equals.

Checks two Permission objects for equality.

Do not use the equals method for making access control decisions; use the implies method.

Parameters

obj:Object: the object we are testing for equality with this object.

Returns:boolean

true if both Permission objects are equivalent.

Annotations

@Override

getActions back to summary

getActions	back to summary
public abstract String getActions() Returns the actions as a `String`. This is abstract so subclasses can defer creating a `String` representation until one is needed. Subclasses should always return actions in what they consider to be their canonical form. For example, two FilePermission objects created via the following: perm1 = new FilePermission(p1,"read,write"); perm2 = new FilePermission(p2,"write,read"); both return "read,write" when the `getActions` method is invoked. Returns:String the actions of this `Permission`.

public abstract String getActions()

Returns the actions as a String. This is abstract so subclasses can defer creating a String representation until one is needed. Subclasses should always return actions in what they consider to be their canonical form. For example, two FilePermission objects created via the following:

  perm1 = new FilePermission(p1,"read,write");
  perm2 = new FilePermission(p2,"write,read");

both return "read,write" when the getActions method is invoked.

Returns:String: the actions of this Permission.

getName back to summary

getName	back to summary
public final String getName() Returns the name of this `Permission`. For example, in the case of a `java.io.FilePermission`, the name will be a pathname. Returns:String the name of this `Permission`.

public final String getName()

Returns the name of this Permission. For example, in the case of a java.io.FilePermission, the name will be a pathname.

Returns:String: the name of this Permission.

hashCode back to summary

hashCode	back to summary
public abstract int hashCode() Overrides java.lang.Object.hashCode. Returns the hash code value for this `Permission` object. The required `hashCode` behavior for `Permission` Objects is the following: Whenever it is invoked on the same `Permission` object more than once during an execution of a Java application, the `hashCode` method must consistently return the same integer. This integer need not remain consistent from one execution of an application to another execution of the same application. If two `Permission` objects are equal according to the `equals` method, then calling the `hashCode` method on each of the two `Permission` objects must produce the same integer result. Returns:int a hash code value for this object. Annotations @Override

public abstract int hashCode()

Overrides java.lang.Object.hashCode.

Returns the hash code value for this Permission object.

The required hashCode behavior for Permission Objects is the following:

Whenever it is invoked on the same Permission object more than once during an execution of a Java application, the hashCode method must consistently return the same integer. This integer need not remain consistent from one execution of an application to another execution of the same application.
If two Permission objects are equal according to the equals method, then calling the hashCode method on each of the two Permission objects must produce the same integer result.

Returns:int

a hash code value for this object.

Annotations

@Override

implies back to summary

implies	back to summary
public abstract boolean implies(Permission permission) Checks if the specified permission's actions are "implied by" this object's actions. This must be implemented by subclasses of `Permission`, as they are the only ones that can impose semantics on a `Permission` object. Parameters permission:Permission the permission to check against. Returns:boolean `true` if the specified permission is implied by this object, `false` if not.

public abstract boolean implies(Permission permission)

Checks if the specified permission's actions are "implied by" this object's actions.

This must be implemented by subclasses of Permission, as they are the only ones that can impose semantics on a Permission object.

Parameters

permission:Permission: the permission to check against.

Returns:boolean

true if the specified permission is implied by this object, false if not.

newPermissionCollection back to summary

newPermissionCollection	back to summary
public PermissionCollection newPermissionCollection() Returns an empty `PermissionCollection` for a given `Permission` object, or `null` if one is not defined. Subclasses of class `Permission` should override this if they need to store their permissions in a particular `PermissionCollection` object in order to provide the correct semantics when the `PermissionCollection.implies` method is called. If `null` is returned, then the caller of this method is free to store permissions of this type in any `PermissionCollection` they choose (one that uses a Hashtable, one that uses a Vector, etc.). Returns:PermissionCollection a new `PermissionCollection` object for this type of `Permission`, or `null` if one is not defined.

public PermissionCollection newPermissionCollection()

Returns an empty PermissionCollection for a given Permission object, or null if one is not defined. Subclasses of class Permission should override this if they need to store their permissions in a particular PermissionCollection object in order to provide the correct semantics when the PermissionCollection.implies method is called. If null is returned, then the caller of this method is free to store permissions of this type in any PermissionCollection they choose (one that uses a Hashtable, one that uses a Vector, etc.).

Returns:PermissionCollection: a new PermissionCollection object for this type of Permission, or null if one is not defined.

toString back to summary

toString	back to summary
public String toString() Overrides java.lang.Object.toString. Returns a string describing this `Permission`. The convention is to specify the class name, the permission name, and the actions in the following format: '("ClassName" "name" "actions")', or '("ClassName" "name")' if actions list is `null` or empty. Returns:String information about this `Permission`.

public String toString()

Overrides java.lang.Object.toString.

Returns a string describing this Permission. The convention is to specify the class name, the permission name, and the actions in the following format: '("ClassName" "name" "actions")', or '("ClassName" "name")' if actions list is null or empty.

Returns:String: information about this Permission.

public abstract Class Permission

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail