Additional Java Syntax - Building Java Programs: A Back to Basics Approach - page 1129

case 3:
System.out.println("You won a medal!!!");
break;
default:
System.out.println("You did not win a medal. Sorry.");
break;
}
Many programmers avoid the switch statement because it is so easy to produce a
bug such as that just described. In older programming languages the switch state-
ment was a more efficient way to execute the if/else statement, but this benefit is
not noticeable in Java.
The try/catch Statement
The try/catch statement “tries” to execute a given block of code (called the “ try
block”). The statement also specifies a second “ catch block” of code that should be
executed if any code in the “ try block” generates an exception of a particular type. It
uses the following syntax:
try {
<statements> ;
} catch ( <type> <name> ) {
<statements> ;
}
For example, the following code attempts to read an input file and prints an error
message if the operation fails:
try {
Scanner input = new Scanner(new File("input.txt"));
while (input.hasNextLine()) {
System.out.println(input.nextLine());
}
} catch (FileNotFoundException e) {
System.out.println("Error reading file: " + e);
}
If you wrap all potentially unsafe operations in a method with the try/catch syn-
tax, you do not need to use a throws clause on that method's header. For example, you
do not need to declare that your main method throws a FileNotFoundException if
you handle it yourself using a try/catch block.
Some variations of the try/catch syntax are not shown here. It is possible to
have multiple catch blocks for the same try block, to handle multiple kinds of