Unchecked Exception in Java

-

In Java, unchecked exceptions are a type of exception that do not need to be declared in a method or caught in a try-catch block. They are also known as runtime exceptions, and they are thrown automatically by the Java runtime system when a program encounters an error or a logical problem at runtime.

Examples of unchecked exceptions in Java include:

  1. NullPointerException - occurs when a program tries to access a null object reference.
  2. ArrayIndexOutOfBoundsException - occurs when a program tries to access an array element that does not exist.
  3. ArithmeticException - occurs when a program attempts to perform an arithmetic operation that is not possible, such as dividing by zero.
  4. IllegalArgumentException - occurs when a method receives an argument that is not valid or outside of the expected range.

Unchecked exceptions are generally used to signal programming errors or other unexpected conditions, and they should be avoided when possible by writing robust code that anticipates and handles all possible error conditions. However, when they do occur, they can be useful for debugging and troubleshooting.


Here's an example of how an unchecked exception (specifically a NullPointerException) can occur in Java code:

java
public class Example {
    public static void main(String[] args) {
        String str = null;
        System.out.println(str.length()); // This line will throw a NullPointerException
    }
}

In this example, we create a String variable called str and set it to null. We then try to call the length() method on str, which will result in a NullPointerException being thrown because str is null and does not have a valid object reference.

Since NullPointerException is an unchecked exception, we don't need to declare it in the main() method or catch it in a try-catch block. Instead, the exception will propagate up the call stack until it is caught by the JVM or terminates the program.

Comments

Post a Comment

Popular posts from this blog

Cryptography API

-
Java offers a comprehensive set of cryptographic functionalities through its `java.security` package. This package provides various classes and interfaces for encryption, decryption, key generation, digital signatures, and more. Here are some key classes and concepts within Java's Cryptography API: 1. **Message Digests (Hashing):** Classes like `MessageDigest` help generate hash values for data using algorithms like MD5, SHA-1, SHA-256, etc. 2. **Encryption/Decryption:** The `Cipher` class allows encryption and decryption using various algorithms like AES, DES, RSA, etc. 3. **Key Management:** Java provides classes such as `KeyGenerator` for generating symmetric keys, `KeyPairGenerator` for key pairs (for asymmetric encryption), and `KeyStore` for managing keys and certificates. 4. **Digital Signatures:** The `Signature` class helps create and verify digital signatures. Here's a simple example demonstrating encryption and decryption using Java's Cryptography API: ```java im...
Read more

Java Applet Overview

-
  An applet in Java is a special type of program that is designed to be executed within a web browser. Applets are written in the Java programming language and can be embedded within an HTML page using the <applet> tag. When the HTML page containing the applet is loaded in a web browser, the applet code is downloaded and executed by the Java Virtual Machine (JVM) built into the browser. Applets are often used to provide interactive functionality on a web page, such as games, animations, and data visualization. They have access to a limited set of features and resources provided by the web browser, such as user input events and graphics libraries, but are restricted from accessing resources on the user's computer or network. In recent years, the use of applets has declined in favor of other technologies such as JavaScript, HTML5, and CSS. However, applets are still supported by some web browsers and can be a useful tool in certain situations where other technologies may not be...
Read more

Vector in Java

-
  In Java, a vector is a resizable collection of objects, similar to an array, but with some additional functionality. A vector can grow or shrink dynamically, and can be accessed using an index just like an array. To use a vector in Java, you first need to import the java.util.Vector package. Then you can create a new vector object using the following syntax: java Copy code Vector<Object> vectorName = new Vector <Object>(); Here, Object can be replaced with any data type that you want to store in the vector. For example, if you want to store integers, you can use: java Copy code Vector<Integer> intVector = new Vector <Integer>(); To add elements to the vector, you can use the add() method: java Copy code intVector.add( 1 ); intVector.add( 2 ); intVector.add( 3 ); To access an element in the vector, you can use the get() method: java Copy code int element = intVector.get( 0 ); // returns the first element (1) You can also use other methods provided...
Read more