![\"Exception](\"https:\/\/techvidvan.com\/tutorials\/wp-content\/uploads\/sites\/2\/2023\/09\/Exception-Handling-with-Method-Overriding.webp\")
<\/a><\/p>\nKey points to consider<\/h3>\n
Exception Type Matching:<\/strong> When a subclass overrides a method, it must adhere to the same or more specific exceptions (subclasses) in its throws clause. In the example, the Car class method startEngine() is allowed to throw EngineStartException (same exception) or any subclass of it.<\/p>\n No Broader Exception:<\/strong> The subclass is not allowed to throw a broader (more general) exception than its superclass counterpart. For instance, you cannot throw an Exception if the superclass method throws EngineStartException.<\/p>\n Unchecked Exceptions:<\/strong> For unchecked exceptions (subclasses of RuntimeException), you’re not bound by the exception rules. You can freely throw unchecked exceptions in overridden methods, regardless of whether the superclass method throws checked exceptions.<\/p>\n Overriding without Exception:<\/strong> If the superclass method doesn’t declare any exceptions (including unchecked exceptions), the subclass is not required to declare any exceptions. It’s allowed to throw exceptions if needed, but it’s not mandatory.<\/p>\n Case 1: <\/strong>If the superclass method does not throw any exceptions (neither checked nor unchecked), the subclass method also cannot throw any exceptions. If the subclass method throw the checked exception, we will get a compile time error.<\/p>\n Here’s an example of Java code where the superclass method does not declare an exception, but the subclass overridden method declares a checked exception:<\/strong><\/p>\n Example code:<\/strong><\/p>\n Output:<\/strong><\/p>\n Java: method() in com.company.Subclass cannot override method() in com.company.Superclass<\/p>\n overridden method does not throw com.company.CustomCheckedException<\/p>\n Explanation:<\/strong><\/p>\n Case 2: <\/strong>If the superclass method does not throw any exceptions (neither checked nor unchecked),Subclass method can choose to throw unchecked exceptions.<\/p>\n Example Code:<\/strong><\/p>\n Output:<\/strong><\/p>\n Superclass method Explanation:<\/strong><\/p>\n In this example, the Superclass defines a method called method() that doesn’t throw any exceptions. The Subclass overrides this method and also doesn’t throw any exceptions. The main method demonstrates how both the superclass and subclass methods can be invoked without any issues.<\/p>\n Case 1: <\/strong>If the superclass method throws a checked exception; the subclass method can:<\/p>\n a. Throw the same exception.<\/p>\n Example Code:<\/strong><\/p>\n Output:<\/strong><\/p>\n SavingsAccount: Insufficient funds for withdrawal<\/p>\n Explanation:<\/strong><\/p>\n Case 2: <\/strong>If the superclass method throws a checked exception, the subclass method can:<\/p>\n b. Throw a subclass exception of the exception thrown by the superclass method.<\/p>\n Example code:<\/strong><\/p>\n Output:<\/strong><\/p>\n Subclass method<\/p>\n Caught:<\/strong> Subclass Exception in Subclass<\/p>\n Explanation:<\/strong><\/p>\n Case 3: <\/strong>If the Parentclass method throws a checked exception, the Childclass method can:<\/p>\n c. Choose not to throw any exception.<\/p>\n Example code:<\/strong><\/p>\n Output:<\/strong><\/p>\n Subclass method<\/p>\n Explanation:<\/strong><\/p>\n Case 4: <\/strong>If the superclass method throws a checked exception, the subclass method can:<\/p>\n d. Cannot throw a parent exception.<\/p>\n Example code:<\/strong><\/p>\n Output:<\/strong><\/p>\n java: method() in com.company.Subclass cannot override method() in com.company.Superclass overridden method does not throw java.lang.Exception<\/p>\n Explanation:<\/strong><\/p>\n In this example, the Subclass attempts to throw a parent exception Exception in its overridden method(). This will result in a compilation error because it is not allowed to throw a parent exception. The Superclass method declares ParentException, and any exception thrown by the Subclass must follow the hierarchy rules.<\/p>\n If the superclass method throws an unchecked exception (subclass of RuntimeException), the subclass method can choose to throw the same exception or any other unchecked exception, including subclasses of RuntimeException.<\/p>\n Example Code:<\/strong><\/p>\n Output:<\/strong><\/p>\n Subclass method<\/p>\n Caught: Unchecked Exception in Subclass<\/p>\n Explanation:<\/strong><\/p>\n When the SuperClass doesn’t specify any exceptions, the SubClass is limited to declaring only unchecked exceptions, excluding checked exceptions.<\/p>\n If the SuperClass specifies an exception, the SubClass is allowed to declare the same exception or its subclasses, along with new RuntimeExceptions. However, it’s restricted from introducing any new checked exceptions at the same level or higher.<\/p>\n In the case of the SuperClass specifying an exception, the SubClass can also choose not to declare any exceptions at all.<\/p>\n","protected":false},"excerpt":{"rendered":" In the following sections, we will unravel the art of harmonizing method overriding and exception handling, shedding light on how these two facets can complement and enhance each other in the pursuit of creating...<\/p>\n","protected":false},"author":1,"featured_media":89028,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[183],"tags":[5232,5233,5234,296,5235,5236],"class_list":["post-88557","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java","tag-exception-handling","tag-exception-handling-with-method-overriding","tag-exception-handling-with-method-overriding-in-java","tag-java","tag-java-exception-handling-with-method-overriding","tag-method-overriding"],"yoast_head":"\nHere are the Problems for exception handling with method overriding in Java:<\/h3>\n
Problem 1 – No Exception in Superclass:<\/h4>\n
class Superclass {\n void method() {\n System.out.println(\"Superclass method\");\n }\n}\nclass Subclass extends Superclass {\n @Override\n void method() throws CustomCheckedException {\n System.out.println(\"Subclass method\");\n throw new CustomCheckedException(\"Checked Exception in Subclass\");\n }\n}\nclass CustomCheckedException extends Exception {\n CustomCheckedException(String message) {\n super(message);\n }\n}\nclass DataFlair{\n public static void main(String[] args) {\n Superclass instance = new Subclass();\n\n try {\n instance.method();\n } catch (CustomCheckedException e) {\n System.out.println(\"Caught: \" + e.getMessage());\n }\n }\n}<\/pre>\n\n
class Superclass {\n void method() {\n System.out.println(\"Superclass method\");\n }\n}\nclass Subclass extends Superclass {\n @Override\n void method() {\n System.out.println(\"Subclass method\");\n }\n}\nclass DataFlair{\n public static void main(String[] args) {\n Superclass superClassInstance = new Superclass();\n Subclass subClassInstance = new Subclass();\n superClassInstance.method(); \/\/ Output: Superclass method\n subClassInstance.method(); \/\/ Output: Subclass method\n }\n}<\/pre>\n
\nSubclass method<\/p>\nProblem 2 – Checked Exception in Superclass:<\/h4>\n
class InsufficientFundsException extends Exception {\n InsufficientFundsException(String message) {\n super(message);\n }\n}\nclass BankAccount {\n protected double balance;\n BankAccount(double initialBalance) {\n this.balance = initialBalance;\n }\n void withdraw(double amount) throws InsufficientFundsException {\n if (amount > balance) {\n throw new InsufficientFundsException(\"Insufficient funds for withdrawal\");\n }\n balance -= amount;\n System.out.println(\"Withdrawal successful. New balance: \" + balance);\n }\n}\nclass SavingsAccount extends BankAccount {\n SavingsAccount(double initialBalance) {\n super(initialBalance);\n }\n @Override\n void withdraw(double amount) throws InsufficientFundsException {\n try {\n super.withdraw(amount); \/\/ Call the superclass method\n } catch (InsufficientFundsException e) {\n System.out.println(\"SavingsAccount: \" + e.getMessage());\n \/\/ Perform additional handling specific to SavingsAccount\n }\n }\n}\nclass DataFlair{\n public static void main(String[] args) {\n BankAccount account1 = new SavingsAccount(1000);\n try {\n account1.withdraw(1500);\n } catch (InsufficientFundsException e) {\n System.out.println(\"Main: \" + e.getMessage());\n \/\/ Perform general handling for all bank accounts\n }\n }\n}<\/pre>\n\n
class ParentException extends Exception {\n ParentException(String message) {\n super(message);\n }\n}\nclass ChildException extends ParentException {\n ChildException(String message) {\n super(message);\n }\n}\nclass Superclass {\n void method() throws ParentException {\n System.out.println(\"Superclass method\");\n throw new ParentException(\"Checked Exception in Superclass\");\n }\n}\nclass Subclass extends Superclass {\n @Override\n void method() throws ChildException {\n System.out.println(\"Subclass method\");\n throw new ChildException(\"Subclass Exception in Subclass\");\n }\n}\nclass DataFlair{\n public static void main(String[] args) {\n Superclass instance = new Subclass();\n\n try {\n instance.method();\n } catch (ParentException e) {\n System.out.println(\"Caught: \" + e.getMessage());\n }\n }\n}<\/pre>\n\n
class ParentException extends Exception {\n ParentException(String message) {\n super(message);\n }\n}\n\nclass Superclass {\n void method() throws ParentException {\n System.out.println(\"Superclass method\");\n throw new ParentException(\"Checked Exception in Superclass\");\n }\n}\n\nclass Subclass extends Superclass {\n @Override\n void method() {\n System.out.println(\"Subclass method\");\n \/\/ No exception thrown in Subclass method\n }\n}\nclass DataFlair{\n public static void main(String[] args) {\n Superclass instance = new Subclass();\n\n try {\n instance.method();\n } catch (ParentException e) {\n System.out.println(\"Caught: \" + e.getMessage());\n }\n }\n}<\/pre>\n\n
class ParentException extends Exception {\n ParentException(String message) {\n super(message);\n }\n}\n\nclass Superclass {\n void method() throws ParentException {\n System.out.println(\"Superclass method\");\n throw new ParentException(\"Checked Exception in Superclass\");\n }\n}\n\nclass Subclass extends Superclass {\n @Override\n void method() throws Exception {\n System.out.println(\"Subclass method\");\n \/\/ Cannot throw ParentException directly here\n throw new Exception(\"Exception in Subclass\"); \/\/ A subclass of Exception\n }\n}\nclass DataFlair{\n public static void main(String[] args) {\n Superclass instance = new Subclass();\n\n try {\n instance.method();\n } catch (ParentException e) {\n System.out.println(\"Caught: \" + e.getMessage());\n }\n }\n}<\/pre>\nProblem 3 – Unchecked Exception in Superclass:<\/h4>\n
class ParentUncheckedException extends RuntimeException {\n ParentUncheckedException(String message) {\n super(message);\n }\n}\nclass Superclass {\n void method() {\n System.out.println(\"Superclass method\");\n throw new ParentUncheckedException(\"Unchecked Exception in Superclass\");\n }\n}\n\nclass ChildUncheckedException extends ParentUncheckedException {\n ChildUncheckedException(String message) {\n super(message);\n }\n}\nclass Subclass extends Superclass {\n @Override\n void method() {\n System.out.println(\"Subclass method\");\n throw new ChildUncheckedException(\"Unchecked Exception in Subclass\");\n }\n}\nclass DataFlair{\n public static void main(String[] args) {\n Superclass superClassInstance = new Subclass();\n\n try {\n superClassInstance.method();\n } catch (ParentUncheckedException e) {\n System.out.println(\"Caught: \" + e.getMessage());\n }\n }\n}<\/pre>\n\n
Conclusion<\/h3>\n