Event dispatching thread: Difference between revisions

Revision as of 01:47, 24 June 2014

Revision as of 07:56, 22 September 2014

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Since programmers often miss this requirement, third-party [[Pluggable look and feel|Look and Feel]]s, like [http://java.net/projects/substance/ Substance] go as far as to refuse to instantiate any Swing component when not running within the Event Dispatch Thread,<ref>http://www.pushing-pixels.org/?p=368</ref> to prevent such a coding mistake. Access to the GUI is serialized and other threads may submit some code to be executed in the EDT through a '''EDT message queue'''.

That is, likewise in other GUI frameworks, the Event Dispatching Thread spends its life pumping messages: it maintains a message queue of actions to be performed over GUI. These requests are sumbittedsubmitted to the queue by system and any application thread. EDT consumes them one after another and responds by updating the GUI components. The messages may be well-known actions or involve callbacks, the references to user-methods that must be executed by means of EDT.

The important requirement imposed on all messages is that they must be executed quickly for the GUI to stay responsive. Otherwise, the message loop is blocked and GUI freezing is experienced.