Java : Instance Initializer block in Java (init block)

/*init block is always executed before any constructor

//if you are not doing constructor chaining then the complete code of init block is

inserted as a first line in every constructor of class*/

//if you have done constructor chaining the complete code of init block is inserted as a first line in

//that constructor which you are not using this () as a first line

//if you want to perform some common task in every constructor of class then put the code of

that task into the init block

class InitBlock {

    int x;

    // init block

    {

        System.out.println(" first init block");

        x = 10;

    }

    // constructor

    InitBlock() {

        System.out.println("default");

        System.out.println(x);

    }

    // constructor

    InitBlock(int x) {

        System.out.println(x);

    }

    // init block

    {

        System.out.println(" secound init block");

    }

    public static void main(String... s) {

        new InitBlock();

        new InitBlock(20);

        new InitBlock();

    }

}

Output :

 first init block

secound init block

 default  10

first init block secound init block

20 first init block secound init block

default 10