Exceptions

Overview

Exception system is a notification mechanism of an error, and generally this occurs by throw statement. A library will raise some exceptions on error, and you can catch it by try-catch statement. And also you can define your own exception as you like by System.defineException().

See below for more details.

• try-catch-finally
• throw
• defineException

Structure of Exception Object

Basically an exception object has following two methods.

Method	Meaning
type()	The name of the exception.
what()	The message of the exception.
printStackTrace()	Outputs a stack trace with function call history.

Examples

Example 1. Handling Exception

Code

YourOwnExceptionClass = System.defineException('YourOwnException');
YourOwnException = YourOwnExceptionClass.create;

class TheClass {
    private initialize() {
        throw YourOwnException("Error!");
    }
}

function test() {
    var x = new TheClass();
    return x;
}

try {
    test();
} catch (e) {
    System.println("Exception Type   : ", e.type());
    System.println("Exception Message: ", e.what());
    e.printStackTrace();
}

Result

Exception Type   : YourOwnException
Exception Message: Error!
Stack Trace Information:
        at function TheClass#initialize(test.kx:6)
        at function TheClass(test.kx:4)
        at function test(test.kx:11)
        at <main-block>(test.kx:16)