JAVA Exception Handling Interview Questions

Exception Handling Interview Questions

Q - All exceptions other than those in the RuntimeException class must be either caught, or declared in a throws clause of any method that can throw them: True or False? If false, explain why.

A - True.

Q - What method of which class would you use to extract the message from an exception object?

A - The getMessage() method of the Throwable class.

Q - Normally, those exception handlers designed to handle exceptions closest to the root of the exception class hierarchy should be placed first in the list of exception handlers: True or False? If false, explain why.

A - False. The above statement has it backwards. Those handlers designed to handle exceptions furthermost from the root of the hierarchy tree should be placed first in the list of exception handlers.

Q - Explain why you should place exception handlers furthermost from the root of the exception hierarchy tree first in the list of exception handlers.

A - An exception hander designed to handle a specialized "leaf" object may be preempted by another handler whose exception object type is closer to the root of the exception hierarchy tree if the second exception handler appears earlier in the list of exception handlers.

Q - In addition to writing handlers for very specialized exception objects, the Java language allows you to write general exception handlers that handle multiple types of exceptions: True or False? If false, explain why.

A - True.

Q - Your exception handler can be written to handle any class that inherits from Throwable. If you write a handler for a node class (a class with no subclasses), you've written a specialized handler: it will only handle exceptions of that specific type. If you write a handler for a leaf class (a class with subclasses), you've written a general handler: it will handle any exception whose type is the node class or any of its subclasses. True or False? If false, explain why.

A - False. "Leaf" and "node" are reversed in the above statement. If you write a handler for a "leaf" class (a class with no subclasses), you've written a specialized handler: it will only handle exceptions of that specific type. If you write a handler for a "node" class (a class with subclasses), you've written a general handler: it will handle any exception whose type is the node class or any of its subclasses."

Q - Java's finally block provides a mechanism that allows your method to clean up after itself regardless of what happens within the try block. True or False? If false, explain why.

A - True.

Q - Explain how you would specify that a method throws one or more exceptions.

A - To specify that a method throws one or more exceptions, you add a throws clause to the method signature for the method. The throws clause is composed of the throws keyword followed by a comma-separated list of all the exceptions thrown by that method.

Q - Provide a code fragment that illustrates how you would specify that a method throws more than one exception.

A - See code fragment below.

 void myMethod() throws InterruptedException, MyException,

       HerException, UrException

  {

  //method body

  }

  

Q - What type of argument is required by the throw statement?

A - The throw statement requires a single argument, which must be an object derived either directly or indirectly

from the class Throwable.

Q - Some exception objects are automatically thrown by the system. It is also possible for you to define your own exception classes, and to cause objects of those classes to be thrown whenever an exception occurs. True or False? If false, explain why.

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