MACROMEDIA FLASH MX 2004 - ACTIONSCRIPT, Справочное руководство

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try..catch..finally 737
Example
The following example shows how to create a
try..finally
statement. Because code in the
finally
block is guaranteed to execute, it is typically used to perform any necessary “clean-up”
code after a
try
block executes. In this example, the
finally
block is used to delete an
ActionScript object, regardless of whether an error occurred.
var account = new Account()
try {
var returnVal = account.getAccountInfo();
if(returnVal != 0) {
throw new Error("Error getting account information.");
}
}
finally {
// Delete the 'account' object no matter what.
if(account != null) {
delete account;
}
}
The following example demonstrates a
try..catch
statement. The code within the
try
block is
executed. If an exception is thrown by any code within the
try
block, control passes to the
catch
block, which displays the error message in a text field using the
Error.toString()
method.
var account = new Account()
try {
var returnVal = account.getAccountInfo();
if(returnVal != 0) {
throw new Error("Error getting account information.");
}
} catch (e) {
status_txt.text = e.toString();
}
The following example shows a
try
code block with multiple, typed
catch
code blocks.
Depending on the type of error that occurred, the
try
code block throws a different type of
object. In this case,
myRecordSet
is an instance of a (hypothetical) class named RecordSet whose
sortRows()
method can throw two different types of errors: RecordSetException and
MalformedRecord.
In this example, the RecordSetException and MalformedRecord objects are subclasses of the
Error class. Each is defined in its own AS class file. (For more information, see
Chapter 9,
“Creating Classes with ActionScript 2.0,” on page 155 .)
// In RecordSetException.as:
class RecordSetException extends Error {
var message = "Record set exception occurred."
}
// In MalformedRecord.as:
class MalformedRecord extends Error {
var message = "Malformed record exception occurred.";
}