Java Exception Handling

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Questions and Answers

What is the purpose of the `finally` block in a Java program?

The finally block is used to execute important code regardless of whether an exception is thrown or not.

What type of exception is thrown when dividing by zero in Java?

ArithmeticException

What is the difference between the `throw` and `throws` keywords in Java?

The throw keyword is used to manually throw an exception, while the throws keyword is used to declare that a method may throw an exception.

What is the purpose of the `catch` block in a Java program?

The <code>catch</code> block is used to handle and process exceptions that are thrown by the <code>try</code> block. Signup and view all the answers

Can a `finally` block be used without a `catch` block?

Yes Signup and view all the answers

What is a multi-catch block in Java?

A multi-catch block is a single <code>catch</code> block that can catch multiple exceptions. Signup and view all the answers

What is the purpose of the `try` block in a Java program?

The <code>try</code> block is used to enclose a block of code that may throw an exception. Signup and view all the answers

Can a `finally` block throw an exception?

Yes Signup and view all the answers

What happens when an exception is thrown in a `try` block and not caught by a `catch` block?

The program will terminate and an error message will be displayed. Signup and view all the answers

What is the purpose of the `NullPointerException` in Java?

The <code>NullPointerException</code> is thrown when a program attempts to access or manipulate a null object reference. Signup and view all the answers

Study Notes

Exception Handling in Java

In Java, only one exception can occur at a time, and only one catch block is executed.
Catch blocks must be ordered from most specific to most general, with the catch block for ArithmeticException coming before the catch block for Exception.

Multiple Catch Blocks

A try block can have multiple catch blocks to handle different exceptions.
Each catch block must contain a different exception handler.

Java Finally Block

The finally block is used to execute important code such as closing connections, streams, etc.
The finally block is always executed, whether an exception is handled or not.
The finally block must be followed by a try or catch block.

Exception Handling Keywords

Keywords used in Java for exception handling:
- Try
- Catch
- Finally
- Throw

Exception Handling Terms

Try: used to enclose a segment of code that may produce an exception.
Catch: placed directly after the try block to handle one or more exception types.
Finally: execute important code such as closing connection, stream, etc.
Throw: to generate an exception or to describe an instance of an exception.

Try-Catch Syntax

Syntax of Java try-catch: try { // code that may throw exception } catch (Exception_class_Name ref) {}
Syntax of try-finally block: try { // code that may throw exception } finally {}

Problem without Exception Handling

Without exception handling, a program will terminate if an exception occurs.
Example: int data = 50 / 0; will throw an ArithmeticException.

Solution with Exception Handling

Using a try-catch block to handle an exception: try { int data = 50 / 0; } catch (ArithmeticException e) { System.out.println(e); }
The program will continue to execute even if an exception occurs.

Internal Working of Java Try-Catch Block

The try block is executed, and if an exception occurs, the catch block is executed.
If no exception occurs, the catch block is skipped.

Catching Multiple Exceptions

A try block can be followed by one or more catch blocks.
Each catch block must contain a different exception handler.
If you have to perform different tasks at the occurrence of different exceptions, use a Java multi-catch block.

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Description

Understanding the concept of multiple catch blocks in Java and how to handle exceptions in a specific order.