Vfrdtyky

Can I define multiple static blocks?

If possible, why should I define muliple static blocks?

yes, you can also make multiple initialisation blocks.

This allows you to place code with the thing initialised.

private static final Map<String, String> map;

static {

   // complex code to initialise map

}



private static final DbConnection conn;

static {

  // handle any exceptions and initialise conn

}

public class TryInitialisation {

static int values = new int[10];

static{

    System.out.println("running initialisation block");

    for (int i=0; i< values.length; i++)

        values[i] = (int) (100.0 * i);

}

static{

    System.out.println("running initialisation block");

    for (int i=0; i< values.length; i++)

        values[i] = (int) (200.0 * i);

}

static{

    System.out.println("running initialisation block");

    for (int i=0; i< values.length; i++)

        values[i] = (int) (300.0 * i);

}

void listValues(){

    for (int i=0; i<values.length; i++)

        System.out.println(" " + values[i]);

}

public static void main(String args) {



TryInitialisation example = new TryInitialisation();

example.listValues(); 

example = new TryInitialisation(); // referencing a new object of same type

example.listValues();

}



}

here is the output:

running initialisation block

running initialisation block

running initialisation block

0

300

600

900

1200

1500

1800

2100

2400

2700

0

300

600

900

1200

1500

1800

2100

2400

2700

The static blocks were executed serially in the order in which they were declared and the values assigned by the first two static blocks is replaced by the final (third static block).

Also one more thing to observe is that the static initialization block(s) ran only once i.e when the class was loaded by the JVM independent of how many objects were created.

You can define multiple static blocks. But I don't think it is really necessary. But if you will define, then they will be executed sequentially. i mean the static block defined first will execute first and the next block will execute next.

Yes. It is possible to define multiple static blocks in a java class. It helps in modularization of your initialization code, which in turn helps in better understanding and readable nature of the code(As peter mentioned).