Exception Handling Program in Java

Last Updated on April 25, 2023 by Prepbytes

The exception handling program in java is to provide a standard mechanism for handling errors and exceptional conditions in a more robust, reliable, and maintainable way, improving the quality and resilience of Java applications.

What is an Exception?

An exception is an event that disrupts the normal flow of a program’s execution. It occurs when the program encounters an error or unexpected condition that it cannot handle, causing it to halt or behave abnormally. Exceptions can be caught and handled by the program, allowing it to recover from errors and continue executing.

What is Exception Handling?

Exception handling is a mechanism in programming that allows a program to gracefully handle errors and unexpected events. When an exception is thrown, the program’s normal execution flow is interrupted, and the exception-handling system takes over. The system searches for a matching exception handler that can handle the specific type of exception, and if found, the handler will execute and attempt to recover from the error. If no matching handler is found, the program will terminate with an error message. Exception handling is essential for creating robust and reliable software that can handle unexpected conditions and recover from errors.

Types of Exception Handling in Java

Here, are the two types of exception handling In java:

• Checked exceptions: These are exceptions that must be handled by the program, either by catching them using a try-catch block or by declaring them in the method signature using the "throws" keyword. Examples of checked exceptions are ClassNotFoundException, SQLException, and IOException.
• Unchecked exceptions: Also known as runtime exceptions, these are exceptions that can be handled but are not required to be. They are typically caused by programming errors such as null pointer exceptions or arithmetic exceptions. Unchecked exceptions can be caught using a try-catch block, but it’s not mandatory to handle them. Examples of unchecked exceptions include NullPointerException, ArithmeticException, and ArrayIndexOutOfBoundsException.

Java Exception Keywords

In Java, there are several keywords related to exception handling that are used to manage and manipulate exceptions. Here are some of the exception keywords in Java:

• try:The try block encloses the code that may throw an exception. If an exception is thrown, the code inside the try block will terminate immediately and the control will be transferred to the catch block.

  Syntax of try:

  try {
      // code throw an exception
  }

• catch: The catch block catches the thrown exception and provides a block of code to handle it. The catch block is executed only if an exception of the specified type is thrown.

  Syntax of catch:

  catch (ExceptionType e) {
      // code to handle ExceptionType
  } 

• finally: If an exception gets thrown or not, the finally block is always executed. This block is frequently used for elimination operations like resource release and file closure.

  Syntax of finally:

  try {
      // code that may throw an exception
  } catch (ExceptionType e) {
      // code to handle ExceptionType
  } finally {
      // optional block of code that is always executed, whether an exception is thrown or not
  }

• throw: An exception can be thrown explicitly using the throw keyword. When an exception is thrown using the throw keyword, it must be caught by a try-catch block or propagated to a higher level.

  Syntax of throw:

  throw new ExceptionType("Error message");

• throws: The throws keyword is used to declare that a method may throw a specific type of exception. When a method is declared with the throws keyword, it must either catch the exception or propagate it to a higher level.

  Syntax of throws:

   public void methodName() throws ExceptionType1, ExceptionType2 {
      // method body that may throw ExceptionType1 or ExceptionType2
  }

Example Code for Exception Handling Program in Java

public class ExceptionHandlingExample {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    System.out.print("Enter a number: ");
    try {
      int num = scanner.nextInt();
      int result = 10 / num;
      System.out.println("Result = " + result);
    } catch (ArithmeticException e) {
      System.out.println("Error: " + e.getMessage());
    } catch (Exception e) {
      System.out.println("Unknown error occurred: " + e.getMessage());
    } finally {
      System.out.println("Program execution completed.");
    }
  }
}

Output:

Note: This code works only in VScode

Explanation of exception handling program in java
In the exception handling program in java, the user is asked to input a number. The program then attempts to perform a division operation with the number 10. If the number entered by the user is 0, an ArithmeticException will be thrown. The try-catch block in the program handles this exception by catching it and printing an error message. The catch block also catches any other exceptions that may occur and prints a generic error message. The finally block is executed regardless of whether an exception occurred or not and is typically used to perform cleanup tasks or release resources.

Advantages of Exception Handling Program in Java

Here are some disadvantages of exception handling in Java:

• It improves code reliability and simplifies error handling.
• They promote code reuse in the program.
• It enables layered exception handling in the program.
• They support advanced recovery in exception handling.

Disadvantages of Exception Handling Program in Java

Here are some disadvantages of exception handling in Java:

• The performance overhead is due to try-catch blocks.
• Using more exception handling can lead to code that is difficult to read and maintain.
• Improper use of exceptions can lead to unexpected program behaviour.
• Catching and handling exceptions at a high level can lead to the masking of underlying issues.

Conclusion
In conclusion, the exception handling program in java is an essential feature of Java programming that allows developers to handle errors and unexpected conditions gracefully. Java provides two types of exceptions, checked and unchecked, that can be handled using the try-catch block. The finally block is used to execute cleanup tasks or release resources. It’s crucial to handle exceptions appropriately to create reliable and robust software. Java’s exception-handling mechanism enables developers to write programs that can handle a wide range of errors and recover from unexpected conditions, ensuring the smooth execution of their applications

Frequently Asked Questions(FAQs)

Q1. What is the purpose of the try-catch block in Java?
Ans: The try-catch block in Java is used to handle exceptions that may occur during program execution. It allows the program to gracefully recover from errors and continue execution.

Q2. Can you have multiple catch blocks in Java?
Ans: Yes, you can have multiple catch blocks in Java. The catch blocks are evaluated in the order they are specified, and the first catch block that matches the exception type is executed.

Q3. What happens if an exception is not caught in Java?
Ans: If an exception is not caught in Java, it will propagate up the call stack until it is caught by a higher-level catch block or reaches the top level of the program. If the exception is not caught at all, the program will terminate with an error message.

Q4. What is the purpose of the finally block in Java?
Ans: The finally block in Java is used to execute code that should be executed regardless of whether an exception occurs or not. It’s typically used to release resources or perform cleanup tasks.

Q5. Can you have a try block without a catch block in Java?
Ans: Yes, you can have a try block without a catch block in Java. However, if an exception is thrown and not caught, the program will terminate with an error message. To prevent this, you can add a finally block to perform cleanup tasks.