Thread: Exception

How to create the your own custoimzed Exception class?

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Here's useful info on creating your own exceptions.

you can create an customized exception by extending the Exception class

sample code for you:

public class MyException extends Exception {

public MyException(String message)
{
super(message);
//System.out.println(message);
}

}




public class ExceptionDemo {

public void displayNumbers() throws MyException
{
for(int i=0;i<10;i++)
{
System.out.println("i= "+i);
if(i==6)
{
throw new MyException("My Exception Occurred");
}
}
}


public static void main(String[] args) throws MyException {

ExceptionDemo exceptionDemo = new ExceptionDemo();
exceptionDemo.displayNumbers();



}

}

Java provides a way to define our own exceptions. It is good practice to defined the custom(user-defined) exceptions for every application. This helps in handling exceptions better and pass additional information along with exception. The hierarchy of custom exceptions can help taking appropriate actions at various module levels.
For more information visit below link.
http://java.meritcampus.com/t/155/Us...ned-exceptions

1. Create a new class whose name should end with Exception like ClassNameException. This is a convention to differentiate an exception class from regular ones.
2. Make the class extends one of the exceptions which are subtypes of the java.lang.Exception class. Generally, a custom exception class always extends directly from the Exception class.
3. Create a constructor with a String parameter which is the detail message of the exception. In this constructor, simply call the super constructor and pass the message.

Java has many built-in exception classes, such as NullPointerException and IllegalArgumentException. At times however, you might want to create your own exception class. For example, as opposed to throwing IllegalArgumentException when a 0 is detected as a divisor during a division operation, you might wish to throw a DivideByZeroException. This exception class does not exist in the Java core API, but you can create one yourself. The seven steps below will show you how to create an exception class in Java.

First, you will create the custom exception class. Open your text editor and type in the following Java statements:
Java Source for Create an Exception Class
The class extends the Exception class that is defined in the Java core API (in the package is java.lang). When extending Exception you are defining a "checked" exception, i.e., an exception that must be caught or thrown. A constructor is provided that passes the message argument to the super class Exception. The Exception class supports a message property.
Save your file as DivideByZeroException.java.
Open a command prompt and navigate to the directory containing your Java program. Then type in the command to compile the source and hit Enter.
Compile Source for Create Exception
Now you will create the program to test your new exception class. Open your text editor and type in the following Java statements:
Java Source for Testing Exception Class
Notice that the divideInt method must provide a throw clause because the method potentially throws the DivideByZeroException. To create the exception object, the program uses the throw keyword followed by the instantiation of the exception object. At runtime, the throw clause will terminate execution of the method and pass the exception to the calling method.
Save your file as TestDivideByZeroException.java.
Open a command prompt and navigate to the directory containing your Java program. Then type in the command to compile the source and hit Enter.
Compile Source for Test Create Exception
Type in the command to run your program and hit Enter.
Run for Test Create Exception
The first call to the divideInt method is successful. The second call, using a divisor of 0, causes the DivideByZeroException to be thrown in the divideInt method. The message passed to the constructor is displayed in the output.