Exception handling:
- Exception in java is an indication of some unusual event.
- Usually it indicates the error.
- Various keywords used in handling the exception are :
- try-A block of source code that is to be monitored for
the exception.
- catch -The catch
block handles the specific type of exception along with the try block.
- finally - It specifies the code that must be executed even
though exception may or may not occur.
- throw - Used to throw specific exception from the program
code.
- throws - It specifies the exceptions that can be thrown by
a particular method.
Syntax:
class class_name
{
try
{
//Exception
occures here
}
catch(Exception_type
exception_variable)
{
//Exception
handling here
}
}
Types of
exception:
1) Built-in
exceptions:
Before using
exception:
public class
Divide_By_Zero {
public static void main(String args[]) {
int a = 0, b = 0, c = 0;
a = 5;
b = 0;
c = a / b;
System.out.println(a + " divide by
zero of value is : " + c);
}
}
Output:
Handling above
error by using exception:
public class
Divide_By_Zero {
public static void main(String args[])
{
int a = 0,b=0,c=0;
try
{
a=5;
b=0;
c=a/b;
}
catch(ArithmeticException e)
{
System.out.println(a+" divide
by zero is infinity.");
}
}
Output:
Another Example
program:
public class
Divide_By_Zero {
public static void main(String args[]) {
int a[] = new int[3];
try {
for (int i = 1; i <= 3; i++) {
a[i] = i * i;
System.out.println("Arrsy
index"+"\t"+"Added value");
System.out.println(i+"\t\t"+a[i]);
}
} catch (ArrayIndexOutOfBoundsException
e) {
System.out.println("Array
index is out of bounds.");
}
}
}
Output:
2) User-defined
exception:
- If you need to
create user-defined exception, must be constructor method.
Example program:
import
java.lang.Exception;
public class
user_defined_exception extends Exception {
public user_defined_exception(String msg) {
super(msg);
}
}
class Objects {
public static void main(String args[]) {
int age=15;
try {
if (age < 21) {
throw new
user_defined_exception("Your age is very less than the condition.");
}
} catch (user_defined_exception e) {
System.out.println("This is
exception block.");
System.out.println(e.getMessage());
} finally {
System.out.println("Finally
exception block is end.");
}
}
}
Output:
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