org.eclipse.swt.internal

Class Callback

java.lang.Object

org.eclipse.swt.internal.Callback

public class Callback
extends Object

Instances of this class represent entry points into Java which can be invoked from operating system level callback routines.

IMPORTANT: A callback is only valid when invoked on the thread which created it. The results are undefined (and typically bad) when a callback is passed out to the operating system (or other code) in such a way that the callback is called from a different thread.

Constructor Summary

Constructors

Constructor and Description
Callback(Object object, String method, int argCount) Constructs a new instance of this class given an object to send the message to, a string naming the method to invoke and an argument count.
Callback(Object object, String method, int argCount, boolean isArrayBased) Constructs a new instance of this class given an object to send the message to, a string naming the method to invoke, an argument count and a flag indicating whether or not the arguments will be passed in an array.
Callback(Object object, String method, int argCount, boolean isArrayBased, long errorResult) Constructs a new instance of this class given an object to send the message to, a string naming the method to invoke, an argument count, a flag indicating whether or not the arguments will be passed in an array and a value to return when an exception happens.

Method Summary

Modifier and Type	Method and Description
void	dispose() Releases the native level resources associated with the callback, and removes all references between the callback and other objects.
long	getAddress() Returns the address of a block of machine code which will invoke the callback represented by the receiver.
static boolean	getEnabled() Returns whether or not callbacks which are triggered at the native level should cause the messages described by the matching Callback objects to be invoked.
static int	getEntryCount() Returns the number of times the system has been recursively entered through a callback.
static String	getPlatform() Returns the SWT platform name.
static void	reset() Immediately wipes out all native level state associated with all callbacks.
static void	setEnabled(boolean enable) Indicates whether or not callbacks which are triggered at the native level should cause the messages described by the matching Callback objects to be invoked.

Methods inherited from class java.lang.Object

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

Constructor Detail

Callback

public Callback(Object object,
                String method,
                int argCount)

Constructs a new instance of this class given an object to send the message to, a string naming the method to invoke and an argument count. Note that, if the object is an instance of Class it is assumed that the method is a static method on that class.

Parameters:

object - the object to send the message to

method - the name of the method to invoke

argCount - the number of arguments that the method takes

Callback

public Callback(Object object,
                String method,
                int argCount,
                boolean isArrayBased)

Constructs a new instance of this class given an object to send the message to, a string naming the method to invoke, an argument count and a flag indicating whether or not the arguments will be passed in an array. Note that, if the object is an instance of Class it is assumed that the method is a static method on that class.

Parameters:

object - the object to send the message to

method - the name of the method to invoke

argCount - the number of arguments that the method takes

isArrayBased - true if the arguments should be passed in an array and false otherwise

Callback

public Callback(Object object,
                String method,
                int argCount,
                boolean isArrayBased,
                long errorResult)

Constructs a new instance of this class given an object to send the message to, a string naming the method to invoke, an argument count, a flag indicating whether or not the arguments will be passed in an array and a value to return when an exception happens. Note that, if the object is an instance of Class it is assumed that the method is a static method on that class.

Parameters:

object - the object to send the message to

method - the name of the method to invoke

argCount - the number of arguments that the method takes

isArrayBased - true if the arguments should be passed in an array and false otherwise

errorResult - the return value if the java code throws an exception

Method Detail

dispose

public void dispose()

Releases the native level resources associated with the callback, and removes all references between the callback and other objects. This helps to prevent (bad) application code from accidentally holding onto extraneous garbage.

getAddress

public long getAddress()

Returns the address of a block of machine code which will invoke the callback represented by the receiver.

Returns:

the callback address

getPlatform

public static String getPlatform()

Returns the SWT platform name.

Returns:

the platform name of the currently running SWT

getEntryCount

public static int getEntryCount()

Returns the number of times the system has been recursively entered through a callback.

Note: This should not be called by application code.

Returns:

the entry count

Since:

2.1

setEnabled

public static final void setEnabled(boolean enable)

Indicates whether or not callbacks which are triggered at the native level should cause the messages described by the matching Callback objects to be invoked. This method is used to safely shut down SWT when it is run within environments which can generate spurious events.

Note: This should not be called by application code.

Parameters:

enable - true if callbacks should be invoked

getEnabled

public static final boolean getEnabled()

Returns whether or not callbacks which are triggered at the native level should cause the messages described by the matching Callback objects to be invoked. This method is used to safely shut down SWT when it is run within environments which can generate spurious events.

Note: This should not be called by application code.

Returns:

true if callbacks should not be invoked

reset

public static final void reset()

Immediately wipes out all native level state associated with all callbacks.

WARNING: This operation is extremely dangerous, and should never be performed by application code.