This class defines the methods necessary to implement a security policy for the safe execution of untrusted code. Before performing potentially sensitive operations, Java calls methods of the SecurityManager object currently in effect to determine whether the operations are permitted. These methods throw a SecurityException if the operation is not permitted. Typical applications do not need to use or subclass SecurityManager. It is typically used only by web browsers, applet viewers, and other programs that need to run untrusted code in a controlled environment.

Prior to Java 1.2, this class is abstract, and the default implementation of each check( ) method throws a SecurityException unconditionally. The Java security mechanism has been overhauled as of Java 1.2. As part of the overhaul, this class is no longer abstract and its methods have useful default implementations, so there is rarely a need to subclass it. checkPermission( ) operates by invoking the checkPermission( ) method of the system object. In Java 1.2 and later, all other check( ) methods of SecurityManager are now implemented on top of checkPermission( ).

public class SecurityManager {
// Public Constructors
     public SecurityManager( );  
// Public Instance Methods
     public void checkAccept(String host, int port);  
     public void checkAccess(ThreadGroup g);  
     public void checkAccess(Thread t);  
1.1  public void checkAwtEventQueueAccess( );  
     public void checkConnect(String ...

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