|
|
|
SUMMARY: NESTED | FIELD | CONSTR | METHOD DETAIL: FIELD | CONSTR | METHOD |
|
FlexDoc/Javadoc 2.0 Demo Java Doc |
Class Console
java.io.Console
All Implemented Interfaces:
public final class Console
Methods to access the character-based console device, if any, associated
with the current Java virtual machine.
Whether a virtual machine has a console is dependent upon the
underlying platform and also upon the manner in which the virtual
machine is invoked. If the virtual machine is started from an
interactive command line without redirecting the standard input and
output streams then its console will exist and will typically be
connected to the keyboard and display from which the virtual machine
was launched. If the virtual machine is started automatically, for
example by a background job scheduler, then it will typically not
have a console.
If this virtual machine has a console then it is represented by a
unique instance of this class which can be obtained by invoking the
System.console() method. If no console device is
available then an invocation of that method will return null.
Read and write operations are synchronized to guarantee the atomic
completion of critical operations; therefore invoking methods
readLine(), readPassword(), format(),
printf() as well as the read, format and write operations
on the objects returned by reader() and writer() may
block in multithreaded scenarios.
Invoking close() on the objects returned by the reader()
and the writer() will not close the underlying stream of those
objects.
The console-read methods return null when the end of the
console input stream is reached, for example by typing control-D on
Unix or control-Z on Windows. Subsequent read operations will succeed
if additional characters are later entered on the console's input
device.
Unless otherwise specified, passing a null argument to any method
in this class will cause a NullPointerException to be thrown.
Security note:
If an application needs to read a password or other secure data, it should
use readPassword() or readPassword(String, Object...) and
manually zero the returned character array after processing to minimize the
lifetime of sensitive data in memory.
Console cons;
char[] passwd;
if ((cons = System.console()) != null &&
(passwd = cons.readPassword("[%s]", "Password:")) != null) {
...
java.util.Arrays.fill(passwd, ' ');
}
Since:
1.6
Author:
Xueming Shen
Method Summary |
|
Returns the Charset object used for
the Console.
|
void |
Flushes the console and forces any buffered output to be written
immediately .
|
|
Writes a formatted string to this console's output stream using
the specified format string and arguments.
|
|
A convenience method to write a formatted string to this console's
output stream using the specified format string and arguments.
|
|
Retrieves the unique Reader object associated
with this console.
|
|
Reads a single line of text from the console.
|
|
Provides a formatted prompt, then reads a single line of text from the
console.
|
char[] |
Reads a password or passphrase from the console with echoing disabled
|
char[] |
Provides a formatted prompt, then reads a password or passphrase from
the console with echoing disabled.
|
|
Retrieves the unique PrintWriter object
associated with this console.
|
Methods inherited from class java.lang. Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Retrieves the unique
PrintWriter object
associated with this console.
Returns:
The printwriter associated with this console
Retrieves the unique
Reader object associated
with this console.
This method is intended to be used by sophisticated applications, for
example, a Scanner object which utilizes the rich
parsing/scanning functionality provided by the Scanner:
Console con = System.console();
if (con != null) {
Scanner sc = new Scanner(con.reader());
...
}
For simple applications requiring only line-oriented reading, use
readLine(String, Object...).
The bulk read operations read(char[]) ,
read(char[], int, int) and
read(java.nio.CharBuffer)
on the returned object will not read in characters beyond the line
bound for each invocation, even if the destination buffer has space for
more characters. The Reader's read methods may block if a
line bound has not been entered or reached on the console's input device.
A line bound is considered to be any one of a line feed ('\n'),
a carriage return ('\r'), a carriage return followed immediately
by a linefeed, or an end of stream.
Returns:
The reader associated with this console
Writes a formatted string to this console's output stream using
the specified format string and arguments.
Parameters:
fmt - A format string as described in
Format string syntax
args - Arguments referenced by the format specifiers in the format
string. If there are more arguments than format specifiers, the
extra arguments are ignored. The number of arguments is
variable and may be zero. The maximum number of arguments is
limited by the maximum dimension of a Java array as defined by
The Java Virtual Machine Specification.
The behaviour on a
null argument depends on the
conversion.
Returns:
This console
Throws:
IllegalFormatException - If a format string contains an illegal syntax, a format
specifier that is incompatible with the given arguments,
insufficient arguments given the format string, or other
illegal conditions. For specification of all possible
formatting errors, see the
Details section
of the formatter class specification.
A convenience method to write a formatted string to this console's
output stream using the specified format string and arguments.
An invocation of this method of the form
con.printf(format, args) behaves in exactly the same way
as the invocation of
con.format(format, args)
.
Parameters:
format - A format string as described in
Format string syntax.
args - Arguments referenced by the format specifiers in the format
string. If there are more arguments than format specifiers, the
extra arguments are ignored. The number of arguments is
variable and may be zero. The maximum number of arguments is
limited by the maximum dimension of a Java array as defined by
The Java Virtual Machine Specification.
The behaviour on a
null argument depends on the
conversion.
Returns:
This console
Throws:
IllegalFormatException - If a format string contains an illegal syntax, a format
specifier that is incompatible with the given arguments,
insufficient arguments given the format string, or other
illegal conditions. For specification of all possible
formatting errors, see the
Details section of the
formatter class specification.
Provides a formatted prompt, then reads a single line of text from the
console.
Parameters:
fmt - A format string as described in
Format string syntax.
args - Arguments referenced by the format specifiers in the format
string. If there are more arguments than format specifiers, the
extra arguments are ignored. The maximum number of arguments is
limited by the maximum dimension of a Java array as defined by
The Java Virtual Machine Specification.
Returns:
A string containing the line read from the console, not
including any line-termination characters, or null
if an end of stream has been reached.
Throws:
IllegalFormatException - If a format string contains an illegal syntax, a format
specifier that is incompatible with the given arguments,
insufficient arguments given the format string, or other
illegal conditions. For specification of all possible
formatting errors, see the
Details section
of the formatter class specification.
Reads a single line of text from the console.
Returns:
A string containing the line read from the console, not
including any line-termination characters, or null
if an end of stream has been reached.
Throws:
public char[] readPassword |
|
Provides a formatted prompt, then reads a password or passphrase from
the console with echoing disabled.
Parameters:
fmt - A format string as described in
Format string syntax
for the prompt text.
args - Arguments referenced by the format specifiers in the format
string. If there are more arguments than format specifiers, the
extra arguments are ignored. The maximum number of arguments is
limited by the maximum dimension of a Java array as defined by
The Java Virtual Machine Specification.
Returns:
A character array containing the password or passphrase read
from the console, not including any line-termination characters,
or null if an end of stream has been reached.
Throws:
IllegalFormatException - If a format string contains an illegal syntax, a format
specifier that is incompatible with the given arguments,
insufficient arguments given the format string, or other
illegal conditions. For specification of all possible
formatting errors, see the
Details
section of the formatter class specification.
public char[] readPassword |
() |
Reads a password or passphrase from the console with echoing disabled
Returns:
A character array containing the password or passphrase read
from the console, not including any line-termination characters,
or null if an end of stream has been reached.
Throws:
Flushes the console and forces any buffered output to be written
immediately .
Specified by:
Returns the
Charset object used for
the
Console.
The returned charset corresponds to the input and output source
(e.g., keyboard and/or display) specified by the host environment or user.
It may not necessarily be the same as the default charset returned from
Charset.defaultCharset().
Returns:
a
Charset object used for the
Console Since:
17
|
|
|
SUMMARY: NESTED | FIELD | CONSTR | METHOD DETAIL: FIELD | CONSTR | METHOD |
|
FlexDoc/Javadoc 2.0 Demo Java Doc |
FlexDoc/Javadoc is a template-driven programming tool for rapid development of any Javadoc-based Java API documentation generators (i.e. doclets). If you need to customize your Javadoc without writing a full-blown doclet from scratch,
FlexDoc/Javadoc may be the only tool able to help you! Find out more at
www.flexdoc.xyz