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Exception handling in Java is a mechanism to handle runtime errors, allowing the normal flow of the application to be maintained. It involves using specific keywords like <code>try</code>, <code>catch</code>, <code>finally</code>, <code>throw</code>, and <code>throws</code>. Find Exception Class Heirarchy Below:<div class="se-component se-image-container __se__float-none" style="width: 100%"><figure style="width: 100%;"><img src="https://www.api.cstechie.com/upload/editor-image/exception-heirachy-class_1725307026648.png" alt="" data-rotate="" data-proportion="true" data-size="100%," data-align="none" data-percentage="100," data-file-name="exception-heirachy-class.png" data-file-size="81123" data-origin="," origin-size="901,591" style="width: 100%;"></figure></div><h2>1. Try-Catch Block</h2><ul><li><code>try</code> block: Code that might throw an exception is placed inside the <code>try</code> block.</li><li><code>catch</code> block: Handles the exception if one occurs. You can have multiple <code>catch</code> blocks to handle different types of exceptions.</li></ul><pre>try { int result = 10 / 0; // This will throw an ArithmeticException } catch (ArithmeticException e) { System.out.println("Cannot divide by zero!"); } </pre> <h2>2. Finally Block</h2><ul><li>The <code>finally</code> block is optional and is used to execute code that must run regardless of whether an exception was caught or not. It's often used for cleanup activities like closing files or releasing resources.</li></ul><pre>try { int result = 10 / 0; } catch (ArithmeticException e) { System.out.println("Cannot divide by zero!"); } finally { System.out.println("This will always be executed."); } </pre> <h2>3. Throw and Throws</h2><ul><li><code>throw</code> keyword: Used to explicitly throw an exception.</li><li><code>throws</code> keyword: Declares that a method may throw exceptions, indicating to the caller that they should handle or propagate the exception.</li></ul>Using throw:<pre>public void checkAge(int age) { if(age &lt; 18) { throw new ArithmeticException("Access denied - You must be at least 18 years old."); } else { System.out.println("Access granted - You are old enough!"); } } </pre>Using throws: <pre>public void myMethod() throws IOException { FileReader file = new FileReader("somefile.txt"); file.read(); } </pre> <h2>4. Custom Exceptions</h2>You can create your own exceptions by extending the <code>Exception</code> class.<pre>class MyCustomException extends Exception { public MyCustomException(String message) { super(message); } } public class Test { public void checkValue(int value) throws MyCustomException { if (value &lt; 0) { throw new MyCustomException("Value cannot be negative!"); } } }</pre> <h2>5. Best Practices</h2><ul><li style="font-size: 18px">Catch specific exceptions: Always try to catch the most specific exception first to ensure proper handling.</li><li style="font-size: 18px">Never swallow exceptions: Avoid empty <code>catch</code> blocks; they make debugging difficult.</li><li style="font-size: 18px">Use finally for cleanup: Ensure resources like files or connections are properly closed in the <code>finally</code> block.</li><li style="font-size: 18px">Custom exceptions: Use custom exceptions for more meaningful error handling in your application.</li></ul><h2> </h2><h2>6. Checked vs. Unchecked Exceptions</h2><ul><li>Checked Exceptions: These are exceptions that are checked at compile-time. Examples include <code>IOException</code>, <code>SQLException</code>, etc. You must either handle them using a <code>try-catch</code> block or declare them using <code>throws</code>.</li><li>Unchecked Exceptions: These are exceptions that occur at runtime and are not checked at compile-time. Examples include <code>ArithmeticException</code>, <code>NullPointerException</code>, etc. They are typically programming errors and do not need to be declared or caught. </li></ul><pre>//Example import java.io.*; public class ExceptionExample { public static void main(String[] args) { try { FileReader file = new FileReader("test.txt"); BufferedReader fileInput = new BufferedReader(file); // Print first 3 lines of file "test.txt" for (int counter = 0; counter &lt; 3; counter++) System.out.println(fileInput.readLine()); fileInput.close(); } catch (FileNotFoundException e) { System.out.println("File not found: " + e.getMessage()); } catch (IOException e) { System.out.println("I/O error occurred: " + e.getMessage()); } finally { System.out.println("This block is executed no matter what."); } } } </pre>In this example, <code>FileNotFoundException</code> and <code>IOException</code> are checked exceptions that must be either caught or declared in the method signature.

Exceptions In java and their Utilities with Examples

Exception Handling In Java

Java has seen significant updates and changes from Java 8 to Java 17. Below is a comparison of the key differences, new features, improvements, and deprecated features between Java 8 and Java 17. <h2>Key Differences and New Features:</h2><h3>Java 8:</h3><ol><li style="font-size: 18px">Lambda Expressions: Introduced to enable functional programming, allowing you to pass functionality as arguments to methods.</li><li style="font-size: 18px">Stream API: Added to facilitate functional-style operations on streams of elements, such as map-reduce transformations on collections.</li><li style="font-size: 18px">Optional: A container object which may or may not contain a non-null value.</li><li style="font-size: 18px">Default Methods: Introduced in interfaces to provide default implementations for methods.</li><li style="font-size: 18px">Nashorn JavaScript Engine: A lightweight, high-performance JavaScript runtime.</li><li style="font-size: 18px">New Date and Time API: Improved date and time handling with the <code>java.time</code> package.</li><li style="font-size: 18px">Method References: Easier syntax for referring to methods.</li></ol><h3>Java 17:</h3><ol><li style="font-size: 18px">Sealed Classes: Allows classes to restrict which other classes or interfaces may extend or implement them.</li><li style="font-size: 18px">Pattern Matching for <code>instanceof</code>: Simplifies common instanceof checks.</li><li style="font-size: 18px">Records: A compact syntax for declaring classes which are transparent holders for shallowly immutable data.</li><li style="font-size: 18px">Text Blocks: Multiline strings, simplifying the inclusion of large text blocks in the code.</li><li style="font-size: 18px">Enhanced <code>switch</code>: <code>switch</code> expressions can now return values, and support for pattern matching.</li><li style="font-size: 18px">Foreign Function &amp; Memory API (Incubator): Provides an API to interact with native code and memory more safely and efficiently.</li><li style="font-size: 18px">Vector API (Incubator): Introduced to express vector computations that compile to optimal vector hardware instructions on supported CPU architectures.</li><li style="font-size: 18px">Deprecation and Removal of RMI Activation: The RMI Activation mechanism has been removed.</li><li style="font-size: 18px">Z Garbage Collector: A scalable low-latency garbage collector.</li><li style="font-size: 18px">Improved Docker Support: Better support for containerized environments, such as Docker.</li><li style="font-size: 18px">Numerous JEPs (JDK Enhancement Proposals): Each JEP brings in a range of new features and improvements.</li></ol>Deprecated and Removed Features <h3>Java 8:</h3><ul><li style="font-size: 18px">Java 8 itself was a major release and did not deprecate or remove many features, but it set the stage for future removals by introducing more robust APIs like the new Date and Time API.</li></ul><h3>Java 17:</h3><ul><li style="font-size: 18px">Removal of Nashorn: The Nashorn JavaScript engine, introduced in Java 8, has been removed.</li><li style="font-size: 18px">Removal of RMI Activation: The Remote Method Invocation (RMI) Activation has been deprecated and removed.</li><li style="font-size: 18px">Applets: Applets were deprecated in Java 9 and have been removed in Java 17.</li><li style="font-size: 18px">Finalization: Finalization has been deprecated for removal in a future release.</li></ul>Performance Improvements <ul><li style="font-size: 18px">Garbage Collection Enhancements: Java 17 includes improvements to the Z Garbage Collector (ZGC) and the Shenandoah GC, providing better performance and lower latency.</li><li style="font-size: 18px">JVM Improvements: The JVM continues to receive performance improvements, making newer versions generally faster and more efficient than older ones.</li></ul>Security Enhancements <ul><li style="font-size: 18px">Enhanced Security Algorithms: Java 17 includes more secure and efficient cryptographic algorithms.</li><li style="font-size: 18px">Improved Container Awareness: Better resource management and security in containerized environments like Docker.</li></ul>Compatibility and Migration <ul><li style="font-size: 18px">Backward Compatibility: Java strives to maintain backward compatibility, but migrating from Java 8 to Java 17 may require changes in the code, especially if deprecated features were used.</li><li style="font-size: 18px">Deprecation Warnings: Pay attention to deprecation warnings in Java 8, as these features may be removed in future versions.</li></ul>Conclusion Java 8 was a major release that introduced a range of features enabling functional programming and modern APIs, making it one of the most widely used versions of Java.Java 17 is the latest Long-Term Support (LTS) version, incorporating numerous new language features, API enhancements, and performance improvements, while also cleaning up older, less secure, or less efficient features.Upgrading from Java 8 to Java 17 offers many benefits in terms of performance, security, and language features. However, it requires careful consideration of code changes due to deprecated and removed features.

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Exception Handling In Java

JAVA 8 VS JAVA 17