Java SE 11 Exception Handling
- 1. Java SE 11 Exception Handling BY: ASHWIN SHIV NIT DELHI
- 3. Introduction Exceptions in Java are any abnormal, unexpected events or extra-ordinary conditions that may occur at runtime. Java Exception Handling is used to handle error conditions in a program systemically by taking the necessary action. The java.lang.Throwable class and all its subclasses are collectively the exception classes.
- 4. Class Hierarchy Throwable has two subclasses: Exception and Error
- 5. What Happens when an Exception occurs in a Java Program When an exception occurs, the method from which the exception originated, creates a special object known as exception object and hands it off to the Runtime System. The exception object contains information about the exception, and the state of the program when the exception occurred. Creating an exception object and handing it to the runtime system is called throwing an exception. You can manually throw an exception by identifying a scenario you considered an exception, but in many cases, it is the Java Virtual Machine(JVM) throwing exceptions manually
- 6. Searching the Call Stack for the Exception Handler
- 7. try catch Clause If an exception occurs at the particular statement of try block, the rest of the block code will not execute and code will fall through to the catch statement. Syntax of try-catch: Unlike other statements such as if and else,the enclosing braces {} sets are required in this case.
- 8. try catch finally clause The finally clause purpose is to clean up the resources.It will always get executed whether an exception occurs in the try clause or not. You can declare a try-finally block also and you can also declare try-catch-finally together also. What you cannot do is just declaring a try clause without a catch,or finally clause.It will result in compiler error. Declaring try-finally Declaring try-catch-finally
- 9. More on try-catch finally You can put a nested try-catch in outer try block or outer catch block or outer finally block.
- 10. throw clause A program can explicitly throw an exception using the throw keyword besides the implicit exception thrown. Syntax:
- 11. throws clause throws clause is used to declare an exception. It gives an information to the programmer that there may occur an exception so it is better for the programmer to provide the exception handling code so that normal flow can be maintained. Syntax:
- 12. Unchecked Exceptions Unchecked Exceptions are those exceptions in which the compiler does not force you to write code to check for the exception or specify the exception. In other words, Unchecked Exceptions are those classes which inherit RuntimeException. Eg: RuntimeException, ArithmeticException, ArrayIndexOutOfBoundsException etc.
- 13. Unchecked Exceptions in Work Output: In this example,the program abruptly ends as the exception is not handled Output In this example,the program continues after the exception has been caught and handled by the catch clause so the program will continue
- 14. Checked Exceptions A Checked Exception is a special designation, for a group of exceptions that the compiler forces compliance of ‘The Catch or Specify Requirement’. Catch or Specify Requirement: It states that code that might throw certain exceptions, must be enclosed by either of the following: A try statement that catches the exception. The try must provide an appropriate handler for the exception. A method that specifies that it can throw Exception. The method must provide a throws clause that lists the exception or an appropriate exception type.
- 15. Checked Exceptions In Work Output Output In this example, the program abruptly ends as the checked exception is not handled. In this example,the program continues after the checked exception has been caught and handled by the catch clause so the program will continue.
- 16. Table to explain which Exceptions are Checked or which are Unchecked
- 17. Thank You