Java uses a keyword try to preface a block of code that is likely to cause Exception Handling
an error condition and “throw” an exception.The catch block is added
immediately after the try block. A catch block “catches” the exception
“thrown” by the try block and handles it appropriately.
…………………….
…………………….
try
{
statement ; //generates an exception
}
catch (Exception- type e)
{
statement ; //processes the exception
}
………………………..
………………………..
The try block can have one or more statements that could generate an
exception. If any one statement generates an exception, the remaining
statements in the try block are skipped and execution jumps to the catch
block that is placed immediately next to the try block.
The catch block can have one or more statements that are necessary to
process the exception. Every try statement should be followed by at least
one catch statement; otherwise compilation error will occur.
The catch statement works like a method definition. A single parameter,
which is reference to the exception object is thrown (by the try block). If
the catch parameter matches with the type of exception object, then the
exception is caught and statements in the catch block will be executed.
Otherwise, the exception is not caught, and the default exception handler
will cause the execution to terminate.
Program 4.3 illustrates the use of try and catch blocks to handle an
arithmetic exception. Note that program 4.3 is a modified version of
Program 4.2.
55
, Core JAVA Program 4.3 Using try and catch for exception handling
class Error3
{
public static void main(String[] args)
{
int x = 10;
int y = 5;
int z = 5;
try
{
inta = x/(y-z); //Exception here
}
catch(ArithmeticException e)
{
System.out.println("Division by zero");
}
int b = x/(y+z);
System.out.println("b=" +y);
}
}
Program 4.3 displays the following output:
Note that the program did not stop when an exception is caused inside try
block. Exception is caught by catch block and it prints the error message,
and then continues the execution, as if nothing has happened. Compare
with the output of Program 4.2 which did not give the value of y.
Program 4.4 shows another example of using exception handling
mechanism.
56
an error condition and “throw” an exception.The catch block is added
immediately after the try block. A catch block “catches” the exception
“thrown” by the try block and handles it appropriately.
…………………….
…………………….
try
{
statement ; //generates an exception
}
catch (Exception- type e)
{
statement ; //processes the exception
}
………………………..
………………………..
The try block can have one or more statements that could generate an
exception. If any one statement generates an exception, the remaining
statements in the try block are skipped and execution jumps to the catch
block that is placed immediately next to the try block.
The catch block can have one or more statements that are necessary to
process the exception. Every try statement should be followed by at least
one catch statement; otherwise compilation error will occur.
The catch statement works like a method definition. A single parameter,
which is reference to the exception object is thrown (by the try block). If
the catch parameter matches with the type of exception object, then the
exception is caught and statements in the catch block will be executed.
Otherwise, the exception is not caught, and the default exception handler
will cause the execution to terminate.
Program 4.3 illustrates the use of try and catch blocks to handle an
arithmetic exception. Note that program 4.3 is a modified version of
Program 4.2.
55
, Core JAVA Program 4.3 Using try and catch for exception handling
class Error3
{
public static void main(String[] args)
{
int x = 10;
int y = 5;
int z = 5;
try
{
inta = x/(y-z); //Exception here
}
catch(ArithmeticException e)
{
System.out.println("Division by zero");
}
int b = x/(y+z);
System.out.println("b=" +y);
}
}
Program 4.3 displays the following output:
Note that the program did not stop when an exception is caused inside try
block. Exception is caught by catch block and it prints the error message,
and then continues the execution, as if nothing has happened. Compare
with the output of Program 4.2 which did not give the value of y.
Program 4.4 shows another example of using exception handling
mechanism.
56
