20.18

java.lang.System

THE PACKAGE JAVA.LANG

20.18.2

public static PrintStream out;

The initial value of this variable is a  standard  output stream, already open and

ready to accept output data. Typically, this corresponds to display output or

another output destination specified by the host environment or user. Note that this

field is not

final

, so its value may be updated if necessary.

For simple Java applications, a typical way to write a line of output data is:

System.out.println(data)

See the

println

 method of class

PrintStream

 ( 22.22).

20.18.3

public static PrintStream err;

The initial value of this variable is a  standard  error output stream, already open

and ready to accept output data. Typically, this corresponds to display output or

another output destination specified by the host environment or user. By conven 

tion, this output stream is used to display error messages or other information that

should come to the immediate attention of a user even if the principal output

stream, the value of the variable

out

, has been redirected to a file or other destina 

tion that is typically not continuously monitored. Note that this field is not

final

,

so its value may be updated if necessary.

20.18.4

public static SecurityManager getSecurityManager()

If a security manager has already been established for the currently running Java

system, a reference to that security manager is returned. Otherwise,

null

 is

returned.

20.18.5

public static void setSecurityManager(SecurityManager s)

throws SecurityException

If a security manager has already been established for the currently running Java

system, a

SecurityException

 is thrown. Otherwise, the argument is established

as the current security manager. If the argument is

null

 and no security manager

has been established, then no action is taken and the method simply returns nor 

mally.

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