Exam 11: Exceptions, and Input Output Operations

Code that could generate an unchecked exception must be coded with a try and catch block.

PrintWriter( File f) throws a FileNotFoundException.

A variable declared inside a try block is still in scope after we exit that try block.

When we read objects from a file using the readObject method, what happens when the end of the file is reached?

Java provides classes and methods to read data from a remote file (located somewhere on the Internet).

Why it is important to place the catch clause with the EOFException ahead of the catch clause with the IOException?

Which of the following methods in the Exception classes returns void?

When we open a file for writing and the file does not exist, what will happen?

You want to handle a suspected exception in your program, so you insert the following try and catch blocks. However, the program generated a compiler error. Improve this program to avoid that problem. 1 2 try 3 { 4 n = Integer.parseInt( s ); 5 System.out.println( "Conversion was successful." ); 6 catch ( NumberFormatException nfe ) 7 System.out.println( "Sorry. incompatible data." ); 8 System.out.println( "\nOutput from getMessage: \n" 9 + nfe.getMessage( ) ); 10 11 System.out.println( "\nOutput from toString: \n" 12 + nfe.toString( ) ); 13 System.out.println( "\nOutput from printStackTrace: " ); 14 nfe.printStackTrace( ); 15 }

It is preferable to place data items from a file in an ArrayList object instead of a fixed-length array when you do not know how many lines are in the file.

What is a token?

The filter method of the DoubleStream interface has the following API, DoubleStream filter( DoublePredicate predicate ). What is DoublePredicate?

Handling a possible illegal operation with a try and catch block will make the code run faster than handling it with a simple if/else construct.

To correct this segment, line 12 should be changed to int n = 1;. 10 public static void main( String [ ] args ) 11 { 12 int n; 13 String s = JOptionPane.showInputDialog( null, 14 "Enter an integer" ); 15 System.out.println( "You entered " + s ); 16 17 try 18 { 19 n = Integer.parseInt( s ); 20 System.out.println( "Conversion was successful." ); 21 }

Melanie writes some code with the public class EmailChecker. She uses try and catch blocks to catch thrown exceptions. A user enters this email address: Javalovre@sw.com. Which of the following is a likely outcome?

Because the readObject method returns a generic object, what must the returned object be?

Which technique is often used when processing a Stream-in particular, calling several methods in order to process the data in the Stream?

Java does not allow objects to be written to or read from a file.

When an object is written to a file, transient instance variables of that object are not written to the file.

At run time, if a non-integer is entered, the call to the parseInt method will generate a(n):