There are four constructors in the Throwable class:
• Throwable ()
• Throwable (String message)
• Throwable (String message, Throwable cause)
• Throwable (Throwable cause)
The first two allow constructing an exception object with or without a String message
encapsulated in the object.
There are several methods in the Throwable class. Three useful methods of the Throwable class that provide information about an exception are the following:
• getMessage ( )-Returns the message that was encapsulated when the object was initiated. It returns null, if there is no message.
• toString ()-returns a brief description about the exception of throwable object.
• printStacktrace ( )-prints the stack trace.
StackTrace is a list of the methods executed in sequence that lead to the exception and it is typically used to show the (unhandled) run-time errors on the screen.
The methods of the Throwable class that deal with StackTrace are the following:
• fililnStackTrace ()
• getStackTrace ()
• printStackTrace ()
• setStackTrace (Stack TraceElement  stack Trace)
When an exceptional condition occurs within a method, the method may instantiate an exception object and hand it to the run-time system to deal with it. This is called throwing an exception.