bundles/org.eclipse.platform.doc.isv/guide/swt_error.htm - platform/eclipse.platform.common - Git at Google

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 <H2>Error handling</H2>

 <P>SWT can trigger three types of exceptions:
 <strong>IllegalArgumentException</strong>,
 <strong><a href="../reference/api/org/eclipse/swt/SWTException.html">SWTException</a></strong>, and
 <strong><a href="../reference/api/org/eclipse/swt/SWTError.html">SWTError</a></strong>.
 Applications should not have to catch any other kind of exception or error
 when calling SWT.</P>

 <blockquote><em>Note: If any other exception besides these three is thrown
 from SWT, it should be considered a bug in the SWT implementation.</em></blockquote>

 <P>Where possible, exceptions are triggered consistently across platforms.
 However, some errors are specific to an SWT implementation on a particular
 platform.</P>


 <H3>IllegalArgumentException</H3>

 <P>The arguments passed in SWT API methods are checked for appropriate state
 and range before any other work is done. An <strong>IllegalArgumentException</strong>
 will be thrown when it is determined that an argument is invalid.</P>

 <P>Code that causes an <strong>IllegalArgumentException</strong> on one platform
 will cause the same exception on a different platform.</P>


 <H3>SWTException</H3>

 <P><strong><a href="../reference/api/org/eclipse/swt/SWTException.html">SWTException</a></strong>
 is thrown when a recoverable error occurs internally in SWT. The error code and
 message text provide a further description of the problem.</P>

 <P>SWT remains in a known stable state after throwing the exception.
 For example, this exception is thrown when an SWT call is made from a non-UI
 thread.</P>


 <H3>SWTError</H3>

 <P><a href="../reference/api/org/eclipse/swt/SWTError.html"><strong>SWTError</strong></a>
 is thrown when an unrecoverable error occurs inside SWT.</P>

 <P>SWT will throw this error when an underlying platform call fails, leaving
 SWT in an unknown state, or when SWT is known to have an unrecoverable error,
 such as running out of platform graphics resources.</P>

 <P>Once an SWT error has occurred, there is little that an application can do
 to correct the problem. These errors should not be encountered during normal
 course of operation in an application, but high reliability applications
 should still catch and report the errors.</P>

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	<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><HTML>
	<HEAD>

	<meta name="copyright" content="Copyright (c) IBM Corporation and others 2000, 2005. This page is made available under license. For full details see the LEGAL in the documentation book that contains this page." >

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	<TITLE>Error handling</TITLE>

	<link rel="stylesheet" type="text/css" HREF="../book.css">
	</HEAD>
	<BODY BGCOLOR="#ffffff">

	<H2>Error handling</H2>

	<P>SWT can trigger three types of exceptions:
	<strong>IllegalArgumentException</strong>,
	<strong><a href="../reference/api/org/eclipse/swt/SWTException.html">SWTException</a></strong>, and
	<strong><a href="../reference/api/org/eclipse/swt/SWTError.html">SWTError</a></strong>.
	Applications should not have to catch any other kind of exception or error
	when calling SWT.</P>

	<blockquote><em>Note: If any other exception besides these three is thrown
	from SWT, it should be considered a bug in the SWT implementation.</em></blockquote>

	<P>Where possible, exceptions are triggered consistently across platforms.
	However, some errors are specific to an SWT implementation on a particular
	platform.</P>


	<H3>IllegalArgumentException</H3>

	<P>The arguments passed in SWT API methods are checked for appropriate state
	and range before any other work is done. An <strong>IllegalArgumentException</strong>
	will be thrown when it is determined that an argument is invalid.</P>

	<P>Code that causes an <strong>IllegalArgumentException</strong> on one platform
	will cause the same exception on a different platform.</P>


	<H3>SWTException</H3>

	<P><strong><a href="../reference/api/org/eclipse/swt/SWTException.html">SWTException</a></strong>
	is thrown when a recoverable error occurs internally in SWT. The error code and
	message text provide a further description of the problem.</P>

	<P>SWT remains in a known stable state after throwing the exception.
	For example, this exception is thrown when an SWT call is made from a non-UI
	thread.</P>


	<H3>SWTError</H3>

	<P><a href="../reference/api/org/eclipse/swt/SWTError.html"><strong>SWTError</strong></a>
	is thrown when an unrecoverable error occurs inside SWT.</P>

	<P>SWT will throw this error when an underlying platform call fails, leaving
	SWT in an unknown state, or when SWT is known to have an unrecoverable error,
	such as running out of platform graphics resources.</P>

	<P>Once an SWT error has occurred, there is little that an application can do
	to correct the problem. These errors should not be encountered during normal
	course of operation in an application, but high reliability applications
	should still catch and report the errors.</P>

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