java.lang.Object
- javax.security.auth.Subject

All Implemented Interfaces:

Serializable
```
public final class Subject
extends Object
implements Serializable
```
A Subject represents a grouping of related information for a single entity, such as a person. Such information includes the Subject's identities as well as its security-related attributes (passwords and cryptographic keys, for example).
Subjects may potentially have multiple identities. Each identity is represented as a Principal within the Subject. Principals simply bind names to a Subject. For example, a Subject that happens to be a person, Alice, might have two Principals: one which binds "Alice Bar", the name on her driver license, to the Subject, and another which binds, "999-99-9999", the number on her student identification card, to the Subject. Both Principals refer to the same Subject even though each has a different name.
A Subject may also own security-related attributes, which are referred to as credentials. Sensitive credentials that require special protection, such as private cryptographic keys, are stored within a private credential Set. Credentials intended to be shared, such as public key certificates or Kerberos server tickets are stored within a public credential Set. Different permissions are required to access and modify the different credential Sets.
To retrieve all the Principals associated with a Subject, invoke the getPrincipals method. To retrieve all the public or private credentials belonging to a Subject, invoke the getPublicCredentials method or getPrivateCredentials method, respectively. To modify the returned Set of Principals and credentials, use the methods defined in the Set class. For example:
```
      Subject subject;
      Principal principal;
      Object credential;

      // add a Principal and credential to the Subject
      subject.getPrincipals().add(principal);
      subject.getPublicCredentials().add(credential);
 
```
This Subject class implements Serializable. While the Principals associated with the Subject are serialized, the credentials associated with the Subject are not. Note that the java.security.Principal class does not implement Serializable. Therefore all concrete Principal implementations associated with Subjects must implement Serializable.
Since:

1.4

See Also:

Principal, DomainCombiner, Serialized Form

Constructor Summary

Constructors
Constructor	Description
`Subject()`	Create an instance of a `Subject` with an empty `Set` of Principals and empty Sets of public and private credentials.
`Subject(boolean readOnly, Set<? extends Principal> principals, Set<?> pubCredentials, Set<?> privCredentials)`	Create an instance of a `Subject` with Principals and credentials.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`static <T> T`	`doAs(Subject subject, PrivilegedAction<T> action)`	Perform work as a particular `Subject`.
`static <T> T`	`doAs(Subject subject, PrivilegedExceptionAction<T> action)`	Perform work as a particular `Subject`.
`static <T> T`	`doAsPrivileged(Subject subject, PrivilegedAction<T> action, AccessControlContext acc)`	Perform privileged work as a particular `Subject`.
`static <T> T`	`doAsPrivileged(Subject subject, PrivilegedExceptionAction<T> action, AccessControlContext acc)`	Perform privileged work as a particular `Subject`.
`boolean`	`equals(Object o)`	Compares the specified Object with this `Subject` for equality.
`Set<Principal>`	`getPrincipals()`	Return the `Set` of Principals associated with this `Subject`.
`<T extends Principal> Set<T>`	`getPrincipals(Class<T> c)`	Return a `Set` of Principals associated with this `Subject` that are instances or subclasses of the specified `Class`.
`Set<Object>`	`getPrivateCredentials()`	Return the `Set` of private credentials held by this `Subject`.
`<T> Set<T>`

Class Subject

Constructor Summary

Method Summary