1: //UnknownOpException.java 2: 3: public class UnknownOpException extends Exception 4: { 5: public UnknownOpException( ) 6: { 7: super("UnknownOpException"); 8: } 9: 10: public UnknownOpException(String message) 11: { 12: super(message); 13: } 14: 15: public UnknownOpException(char op) 16: { 17: super(op + " is an unknown operator."); 18: } 19: }