Static Blocks in Java

• Static blocks executed only once when the class is loaded into the memory for the first time.

  public class Main {
    {
        System.out.println("inside instance block");
    }
  
    static {
        System.out.println("inside static block");
    }
  
    public static void main(String[] args) {
        new Main();
        new Main();
        System.out.println("Main Program ");
    }
  }
  //output
  inside static block
  inside instance block
  inside instance block
  Main Program
  

• A static block will be executed even if there is no main method, for example we print something on the console without creating main() method.

  class Main {
    static {
        System.out.print("Static block without main method");
    }
  }
  //output (works only if JDK version is 1.6 or previous)
  Static block without main method
  

• Static blocks gets executed before the constructor
• Static blocks are used for the initialization of static variables
• A class can have any number of static blocks, and they can appear anywhere in the class body.
• If there are multiple static blocks then those will be executed from top to bottom.