Reference types - Data Structures and Problem Solving Using Java - page 49

figure 2.11
Simple program to
illustrate exceptions

1 import java.util.Scanner;
2
3 public class DivideByTwo
4 {
5 public static void main( String [ ] args )
6 {
7 Scanner in = new Scanner( System.in );
8 int x;
9
10 System.out.println( "Enter an integer: " );
11 try
12 {
13 String oneLine = in.nextLine( );
14 x = Integer.parseInt( oneLine );
15 System.out.println( "Half of x is " + ( x / 2 ) );
16 }
17 catch( NumberFormatException e )
18 { System.out.println( e ); }
19 }
20 }

1. If the try block executes without exception, control passes to

the finally block. This is true even if the try block exits prior to
the last statement via a return , break , or continue .

2. If an uncaught exception is encountered inside the try block,

control passes to the finally block. Then, after executing the
finally block, the exception propagates.

3. If a caught exception is encountered in the try block, control

passes to the appropriate catch block. Then, after executing the
catch block, the finally block is executed.

2.5.3 common exceptions

There are several types of standard exceptions in Java. The standard run-
time exceptions include events such as integer divide-by-zero and illegal
array access. Since these events can happen virtually anywhere, it would
be overly burdensome to require exception handlers for them. If a catch
block is provided, these exceptions behave like any other exception. If a
catch block is not provided for a standard exception, and a standard excep-
tion is thrown, then it propagates as usual, possibly past main . In this case,
it causes an abnormal program termination, with an error message. Some
of the common standard runtime exceptions are shown in Figure 2.12.
Generally speaking, these are programming errors and should not be

Runtime excep-
tions do not have to
be handled.