com.isti.util

Class ProgramSingleton

java.lang.Object

com.isti.util.ProgramSingleton

public class ProgramSingleton
extends java.lang.Object

Class ProgramSingleton creates a "program singleton" file used to determine if another instance of the given program is already running. The name of the "program singleton" file will be the program name given to the constructor plus the extension ".psf".

The standard usage of this class is to call the 'initialize()' method in the main method of the program (aborting if the method returns false) and call the 'close()' method from the shutdown-hook for the program (setup via 'Runtime.getRuntime().addShutdownHook()').

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	SINGLETON_FILE_EXT The singleton file extension.

Constructor Summary

Constructors

Constructor and Description
ProgramSingleton(java.io.File singletonFileObj) Creates a "program singleton" file.
ProgramSingleton(java.io.File parent, java.lang.String programNameStr) Creates a "program singleton" file.
ProgramSingleton(java.lang.String programNameStr) Creates a "program singleton" file.
ProgramSingleton(java.lang.String parent, java.lang.String programNameStr) Creates a "program singleton" file.

Method Summary

Modifier and Type	Method and Description
void	close() Unlocks and deletes the "program singleton" file.
boolean	initialize() Checks to see if another instance of the program is running and, if not, creates and locks a "program singleton" file.
boolean	isRunning() Determines if this program is running or not.
java.lang.String	toString() Returns a string representation of the object.
boolean	waitForClose(int millis) Wait for the program close.
boolean	waitForClose(int millis, int retry) Wait for the program close.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

SINGLETON_FILE_EXT

public static final java.lang.String SINGLETON_FILE_EXT

The singleton file extension.

See Also:

Constant Field Values

Constructor Detail

ProgramSingleton

public ProgramSingleton(java.io.File singletonFileObj)

Creates a "program singleton" file.

Parameters:

singletonFileObj - the singleton file object.

ProgramSingleton

public ProgramSingleton(java.io.File parent,
                        java.lang.String programNameStr)

Creates a "program singleton" file.

Parameters:

parent - the parent file.

programNameStr - the program name to be used.

ProgramSingleton

public ProgramSingleton(java.lang.String programNameStr)

Creates a "program singleton" file.

Parameters:

programNameStr - the program name to be used.

ProgramSingleton

public ProgramSingleton(java.lang.String parent,
                        java.lang.String programNameStr)

Creates a "program singleton" file.

Parameters:

parent - the parent pathname string.

programNameStr - the program name to be used.

Method Detail

close

public void close()

Unlocks and deletes the "program singleton" file.

initialize

public boolean initialize()

Checks to see if another instance of the program is running and, if not, creates and locks a "program singleton" file.

Returns:

true if successful, false if another instance of the program is already running.

isRunning

public boolean isRunning()

Determines if this program is running or not.

Returns:

true if this program is running, false otherwise.

toString

public java.lang.String toString()

Returns a string representation of the object.

Overrides:

toString in class java.lang.Object

Returns:

a string representation of the object.

waitForClose

public boolean waitForClose(int millis)

Wait for the program close.

Parameters:

millis - Waits at most millis milliseconds for this program to close. A timeout of 0 means to wait forever.

Returns:

true if the program closed, false otherwise.

waitForClose

public boolean waitForClose(int millis,
                            int retry)

Wait for the program close.

Parameters:

millis - Waits at most millis milliseconds for this program to close. A timeout of 0 means to wait forever.

retry - the number of millis to wait between retries.

Returns:

true if the program closed, false otherwise.