exceptions
Create custom Exception example
This is an example of how to create and use a custom exception that will be thrown in a specified condition. In order to create a custom exception and use it in a method invocation we have followed the steps below:
- We have created an
InvalidPassException
class that extends the Exception and uses the Exception’s constructors in its constructors. - We have created a method
void checkPass(String pass)
, that checks a String password’s validity and throws anInvalidPassException
if the password’s length is shorter that a specific min length. - We create a
try-catch
block where we invoke thecheckPass(String pass)
method and catch theInvalidPassException
.
Let’s take a look at the code snippet that follows:
package com.javacodegeeks.snippets.basics; public class CustomExceptionExample { public static void main(String[] args) { // We demonstrate with a short password try { CustomExceptionExample.checkPass("pass"); } catch (InvalidPassException e) { e.printStackTrace(); } // We demonstrate with no password try { CustomExceptionExample.checkPass(null); } catch (InvalidPassException e) { e.printStackTrace(); } } // Our business method that check password validity and throws InvalidPassException public static void checkPass(String pass) throws InvalidPassException { int minPassLength = 5; try { if (pass.length() < minPassLength) throw new InvalidPassException("The password provided is too short"); } catch (NullPointerException e) { throw new InvalidPassException("No password provided", e); } } } // A custom business exception class InvalidPassException extends Exception { InvalidPassException() { } InvalidPassException(String message) { super(message); } InvalidPassException(String message, Throwable cause) { super(message, cause); } }
This was an example of how to create and use a custom exception in Java.