A method can explicitly throw an exception. Statement
throw e;throws exception e. An exception is an object, and you usually construct it at the point where you throw it. For example,
throw new IOException("I could not write file out.txt");
throws an IOException with a string that indicates
why the exception was thrown.
To create a new kind of exception, write a class that extends another exception class (typically Exception or RuntimeException). (Extension of a class is part of inheritance, which is not covered in these notes.) For example, the following creates a new kind of RunTimeException called GremlinException.
class GremlinException extends RunTimeException
{
public GremlinException() {}
public String toString()
{
return "GremlinException";
}
}