The Throwable class is the superclass of all errors
and exceptions in the Java language. Only objects that are
instances of this class (or of one of its subclasses) are thrown
by the Java Virtual Machine or can be thrown by the Java
throw statement. Similarly, only this class or one of
its subclasses can be the argument type in a catch
clause.
Instances of two subclasses, {@link java.lang.Error} and
{@link java.lang.Exception}, are conventionally used to indicate
that exceptional situations have occurred. Typically, these instances
are freshly created in the context of the exceptional situation so
as to include relevant information (such as stack trace data).
By convention, class Throwable and its subclasses have
two constructors, one that takes no arguments and one that takes a
String argument that can be used to produce an error
message.
A Throwable class contains a snapshot of the
execution stack of its thread at the time it was created. It can
also contain a message string that gives more information about
the error.
Here is one example of catching an exception:
try {
int a[] = new int[2];
int b = a[4];
} catch (ArrayIndexOutOfBoundsException e) {
System.out.println("exception: " + e.getMessage());
e.printStackTrace();
}
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