23. When should we use static block?

When should we use static block?

• A class can have multiple static blocks
• We can use the static block to initialize the value for static member in a class. Static block always execute one time at the class loading time and before the main method is execute.

  Example:
  
  public class StaticBlockExample {
  // Static member variables
  private static int staticInt;
  private static double staticDouble;
  private static String staticString;

  // Static block for initialization
  static {
  System.out.println(“Static block is executed.”);

  // Initialize the static member variables
  staticInt = 100;
  staticDouble = 99.99;
  staticString = “Hello, World!”;
  }

  // Static methods to get the values of the static member variables
  public static int getStaticInt() {
  return staticInt;
  }

  public static double getStaticDouble() {
  return staticDouble;
  }

  public static String getStaticString() {
  return staticString;
  }

  public static void main(String[] args) {
  // Print the values of the static member variables
  System.out.println(“Static integer: ” + getStaticInt());
  System.out.println(“Static double: ” + getStaticDouble());
  System.out.println(“Static string: ” + getStaticString());
  }
  }

• We also can use static block for building singleton pattern or read the configuration file.

  Example
  public class Singleton {
  // The single instance of the class
  private static Singleton instance;

  // Static block for initialization
  static {
  try {
  // Simulate some complex initialization
  System.out.println(“Static block is executed for Singleton.”);
  instance = new Singleton();
  } catch (Exception e) {
  throw new RuntimeException(“Exception occurred during Singleton creation”, e);
  }
  }

  // Private constructor to prevent instantiation
  private Singleton() {
  // Private constructor
  }

  // Method to get the single instance of the class
  public static Singleton getInstance() {
  return instance;
  }

  // Example method
  public void showMessage() {
  System.out.println(“Hello World from Singleton!”);
  }

  public static void main(String[] args) {
  // Get the Singleton instance and call its method
  Singleton singleton = Singleton.getInstance();
  singleton.showMessage();
  }
  }