What is the main idea of error handling in Java?

Exception handling in Java is based on the try-catch-finally mechanism.

The main idea is as follows:

• Separating normal code from error handling code. Code that may throw an exception is placed in the try block. Code that handles a specific exception is placed in the catch block.
• Explicit declaration of possible errors. Java requires methods that can throw a checked exception to declare it using throws. This allows the calling code to be aware of potential issues and either handle them or pass them on.
• Ensuring resource cleanup. The finally block guarantees the execution of certain code (e.g., closing files or releasing connections), regardless of whether an exception was thrown or not.

This increases code reliability and readability, making error management predictable.

// Example of exception handling
try {
    // Code that may generate an exception (e.g., division by zero)
    int result = 10 / 0;
} catch (ArithmeticException e) {
    // Handling a specific exception
    System.err.println("An arithmetic error occurred: " + e.getMessage());
} finally {
    // Code that always executes (e.g., resource cleanup)
    System.out.println("This block executes regardless of exceptions.");
}

In Java, there are three types of exceptions:

• Checked Exceptions: Must be either caught or declared with throws.
• Unchecked Exceptions (Runtime Exceptions): Not mandatory to handle or declare. Usually indicate programming errors.
• Errors: Serious problems that are usually impossible to recover from. They should not be handled.

Comparison of Checked and Unchecked exceptions:

Attribute	Checked Exceptions	Unchecked Exceptions (Runtime Exceptions)
Requires handling/declaration	Yes	No
Examples	IOException, FileNotFoundException	NullPointerException, ArrayIndexOutOfBoundsException
Purpose	Indicate expected errors that may occur due to external environment	Indicate logical errors in code