java validation exception

in java, validation exceptions are often used to indicate that an object's state does not meet certain criteria or constraints. this is particularly useful in scenarios where you want to enforce rules on input data or application state before proceeding with operations like saving data to a database or performing business operations.

### what is a validation exception?

a validation exception is typically a custom exception that extends the standard `exception` class or its subclasses. by creating a custom validation exception, you can encapsulate specific validation errors that occur during runtime, providing more meaningful error handling in your application.

### when to use validation exceptions

- **input validation**: when user input does not meet the required format or constraints.
- **business logic validation**: when an operation violates business rules.
- **model state validation**: when an object does not conform to required state before being processed.

### steps to create a validation exception

1. **define a custom exception class**: extend the `exception` class or one of its subclasses.
2. **throw the exception**: use the `throw` keyword when validation fails.
3. **catch the exception**: handle the exception where appropriate in your application.

### example code

here's a simple example demonstrating the use of a custom validation exception in a java application.

#### step 1: define the validation exception

#### step 2: create a user class with validation

#### step 3: use the user class

### explanation of the code

1. **validationexception class**: this is a custom exception class that takes a message as an argument, which describes the validation error.

2. **user class**: this class represents a user. it contains:
- a constructor that initializes the username and email.
- setters for username and email that throw a `validationexception` if the provided values do not meet the required criteria.

3. **main class**: this is the entr ...

#python exception handling
#python exception handling best practices
#python exception get message
#python exception list
#python exception message

python exception handling
python exception handling best practices
python exception get message
python exception list
python exception message
python exception as e
python exception groups
python exception print stack trace
python exception
python exception to string
python javascript parser
python java c++
python javatpoint
python java
python java interop
python java or c++
python javalang
python javadoc