EXCEPTION HANDLING AND TEXT I/O - Introduction to Java Programming: Comprehensive Version - page 482

12.32

Rewrite the code in the preceding question using a try-with-resources syntax.

12.33

How do you create a Scanner to read data from a file? What is the reason to define
throws Exception in the main method in Listing 12.15, ReadData.java? What
would happen if the close() method were not invoked in Listing 12.15?

12.34

What will happen if you attempt to create a Scanner for a nonexistent file? What
will happen if you attempt to create a PrintWriter for an existing file?

12.35

Is the line separator the same on all platforms? What is the line separator on Windows?

12.36

Suppose you enter 45 57.8 789 , then press the Enter key. Show the contents of the
variables after the following code is executed.

Scanner input = new Scanner(System.in);
int intValue = input.nextInt();
double doubleValue = input.nextDouble();
String line = input.nextLine();

12.37

Suppose you enter 45 , press the Enter key, 57.8 , press the Enter key, 789 , and press
the Enter key. Show the contents of the variables after the following code is executed.

Scanner input = new Scanner(System.in);
int intValue = input.nextInt();
double doubleValue = input.nextDouble();
String line = input.nextLine();

12.12 Reading Data from the Web
Just like you can read data from a file on your computer, you can read data from a file
on the Web.

Key
Point

In addition to reading data from a local file on a computer or file server, you can also access
data from a file that is on the Web if you know the file's URL (Uniform Resource Locator—
the unique address for a file on the Web). For example, www.google.com/index.html is the URL
for the file index.html located on the Google Web server. When you enter the URL in a Web
browser, the Web server sends the data to your browser, which renders the data graphically.
Figure 12.10 illustrates how this process works.

Client Server

Web
Browser

Web
Server

Internet

Application
Program

Local files

F IGURE 12.10

The client retrieves files from a Web server.

For an application program to read data from a URL, you first need to create a URL object
using the java.net.URL class with this constructor:

public URL(String spec) throws MalformedURLException

For example, the following statement creates a URL object for http://www.google.com/index.html .

1 try {
2 URL url = new URL( "http://www.google.com/index.html" );
3 }