Chapter 13 Exception Handling

1.         See the section "Exceptions and Exception Types." The Throwable class is the root of Java exception classes. Error and Exception are subclasses of Throwable. Error describes fatal system errors, and Exception describes the errors that can be handled by Java programs. The subclasses of Error are LinkageError, VirtualMachineError, and AWTError. The subclasses of Exception include RuntimeException, IOException, AWTException, and InstantiationException.

 

2.         The purpose of claiming exceptions is to tell the Java runtime system what can go wrong. You claim an exception using the throws keyword in the method declaration. You can claim multiple exceptions, separated by commas.

 

3.         You use the throw statement in the method to throw an exception. You cannot throw multiple exceptions in a single throw statement.

 

4.         throw is for throwing exceptions and throws is for claiming exceptions.

 

5.         When an exception occurs, the Java runtime system creates an object for the exception, and the catch process starts.

 

6.         Use a try-catch block to catch exceptions.

 

7.         No.

 

8.         Will statement3 be executed?

Answer: No.

 

            If the exception is not caught, will statement4 be executed?

            Answer: No.

 

            If the exception is caught in the catch clause, will statement4 be executed?

            Answer: Yes.

 

            If the exception is passed to the caller, will statement4 be executed?

            Answer: No.

 

9.               Will statement5 be executed if the exception is not caught?

                        Answer: No.

 

If the exception is of type Exception3, will statement4 be executed? Will statement5 be executed?

                        Answer: This exception is caught by the catch (Exception3 e3) clause and statement4 will be executed, but statement5 will not be executed because it is rethrown to its caller.

 

10.       It does not have a catch clause.

 

11.       Welcome to Java

The finally clause is executed

 

12.       Welcome to Java

The finally clause is executed

Note: the finally clause is always executed!

 

13.       Welcome to Java

The finally clause is executed

 

14.       Welcome to Java

Welcome to HTML

The finally clause is executed

 

15.       Welcome to Java

RuntimeException caught

The finally clause is executed

 

16.       Welcome to Java

Welcome to HTML

The finally clause is executed

End of Block

 

17.       Welcome to Java

The finally clause is executed

End of Block

 

18.       RuntimeException is a subclass of Exception. Therefore, RuntimeException should be caught before Exception.

 

19.       Rational operation error

 

20.       Rational operation error

 

21.       Rational operation error

            After the method call

 

22.       Rational operation error

            Rational operation error

 

23.       If an exception were not caught in a non-GUI application, the program would terminate. If an exception were not caught in a GUI application, the program would continue and the error message would be reported on the console.

 

24.       To print trace information to the console.