Exception handling

• Exceptions are errors that occur at run time.

• The exception handling subsystem in Java allows you to handle errors in a structured and controlled way.

• Java provides easy-to-use and flexible support for exception handling.

• The main advantage is the automation of the error handling code, which previously had to be done manually.

• In older languages, you had to manually check error codes returned by methods, which was tedious and error-prone.

• Exception handling optimizes this checking by automatically executing a block of code (exception handler) when an error occurs.

• No need to manually check the success or failure of each operation or method call.

• Java defines standard exceptions for common errors such as division by zero or file not found.

• The program needs to be prepared to handle these exceptions.

• The Java API library uses exceptions extensively.

• Being a good Java programmer involves mastering the exception handling subsystem.

Hierarchy of exceptions

• In Java, all exceptions are represented by classes.

• All exception classes derive from the Throwable class.

• When an exception occurs, an object of an exception class is generated.

• There are two direct subclasses of Throwable: Exception and Error.

• Exceptions of type Error are related to errors in the Java Virtual Machine (JVM) and not in programs.

• Errors are generally not handled by programs, as they are beyond the developer's control.

• Errors related to program activity are represented by Exception subclasses.

• Examples of program errors: division by zero, exceeding array limits and file errors.

• Programs must handle Exception exceptions.

• RuntimeException is an important subclass of Exception, representing common runtime errors.

(source: https://codegym.cc/groups/posts/exceptions-in-java)

1 Checked Exceptions: These are exceptions that the compiler forces the developer to handle.

2 Unchecked Exceptions: These are exceptions that do not need to be checked by the compiler. They are subclasses of RuntimeException and generally occur due to programmer logic errors.

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