public abstract class

Scheduler

extends Object
java.lang.Object
   ↳ com.google.gwt.core.client.Scheduler
Known Direct Subclasses

Class Overview

This class provides low-level task scheduling primitives. Any exceptions thrown by the command objects executed by the scheduler will be passed to the GWT.UncaughtExceptionHandler if one is installed.

See Also

Summary

Nested Classes
interface Scheduler.RepeatingCommand General-purpose Command interface for tasks that repeat. 
interface Scheduler.ScheduledCommand General-purpose Command interface. 
Public Constructors
Scheduler()
Public Methods
static Scheduler get()
Returns the default implementation of the Scheduler API.
abstract void scheduleDeferred(Scheduler.ScheduledCommand cmd)
A deferred command is executed after the browser event loop returns.
abstract void scheduleEntry(Scheduler.RepeatingCommand cmd)
An "entry" command will be executed before GWT-generated code is invoked by the browser's event loop.
abstract void scheduleEntry(Scheduler.ScheduledCommand cmd)
An "entry" command will be executed before GWT-generated code is invoked by the browser's event loop.
abstract void scheduleFinally(Scheduler.RepeatingCommand cmd)
A "finally" command will be executed before GWT-generated code returns control to the browser's event loop.
abstract void scheduleFinally(Scheduler.ScheduledCommand cmd)
A "finally" command will be executed before GWT-generated code returns control to the browser's event loop.
abstract void scheduleFixedDelay(Scheduler.RepeatingCommand cmd, int delayMs)
Schedules a repeating command that is scheduled with a constant delay.
abstract void scheduleFixedPeriod(Scheduler.RepeatingCommand cmd, int delayMs)
Schedules a repeating command that is scheduled with a constant periodicity.
abstract void scheduleIncremental(Scheduler.RepeatingCommand cmd)
Schedules a repeating command that performs incremental work.
[Expand]
Inherited Methods
From class java.lang.Object

Public Constructors

public Scheduler ()

Public Methods

public static Scheduler get ()

Returns the default implementation of the Scheduler API.

public abstract void scheduleDeferred (Scheduler.ScheduledCommand cmd)

A deferred command is executed after the browser event loop returns.

public abstract void scheduleEntry (Scheduler.RepeatingCommand cmd)

An "entry" command will be executed before GWT-generated code is invoked by the browser's event loop. The Scheduler.RepeatingCommand will be called once per entry from the event loop until false is returned. This type of command is appropriate for instrumentation or code that needs to know when "something happens."

If an entry command schedules another entry command, the second command will be executed before control flow continues to the GWT-generated code.

public abstract void scheduleEntry (Scheduler.ScheduledCommand cmd)

An "entry" command will be executed before GWT-generated code is invoked by the browser's event loop. This type of command is appropriate for code that needs to know when "something happens."

If an entry command schedules another entry command, the second command will be executed before control flow continues to the GWT-generated code.

public abstract void scheduleFinally (Scheduler.RepeatingCommand cmd)

A "finally" command will be executed before GWT-generated code returns control to the browser's event loop. The execute() method will be called once per exit to the event loop until false is returned. This type of command is appropriate for instrumentation or cleanup code.

If a finally command schedules another finally command, the second command will be executed before control flow returns to the browser.

public abstract void scheduleFinally (Scheduler.ScheduledCommand cmd)

A "finally" command will be executed before GWT-generated code returns control to the browser's event loop. This type of command is used to aggregate small amounts of work before performing a non-recurring, heavyweight operation.

If a finally command schedules another finally command, the second command will be executed before control flow returns to the browser.

Consider the following: 

 try {
   nativeEventCallback(); // Calls scheduleFinally one or more times
 } finally {
   executeFinallyCommands();
 }

See Also

public abstract void scheduleFixedDelay (Scheduler.RepeatingCommand cmd, int delayMs)

Schedules a repeating command that is scheduled with a constant delay. That is, the next invocation of the command will be scheduled for delayMs milliseconds after the last invocation completes.

For example, assume that a command takes 30ms to run and a 100ms delay is provided. The second invocation of the command will occur at 130ms after the first invocation starts.

Parameters
cmd the command to execute
delayMs the amount of time to wait after one invocation ends before the next invocation

public abstract void scheduleFixedPeriod (Scheduler.RepeatingCommand cmd, int delayMs)

Schedules a repeating command that is scheduled with a constant periodicity. That is, the command will be invoked every delayMs milliseconds, regardless of how long the previous invocation took to complete.

Parameters
cmd the command to execute
delayMs the period with which the command is executed

public abstract void scheduleIncremental (Scheduler.RepeatingCommand cmd)

Schedules a repeating command that performs incremental work. This type of command is encouraged for long-running processes that perform computation or that manipulate the DOM. The commands in this queue are invoked many times in rapid succession and are then deferred to allow the browser to process its event queue.

Parameters
cmd the command to execute