Java For Dummies Quick Reference

Initializer

An initializer is a line of code (or a block of code) placed outside any method, constructor, or other block of code. Initializers are executed whenever an instance of a class is created, regardless of which constructor is used to create the instance.

The simplest initializers are those that declare and initialize fields. For example:

class Class1

{

public int x = 0;

// other class constructors and members go here

}

The variable x is declared and initialized to a value of 0 (zero).

An initializer can also be a block of code enclosed within parentheses, as in this example:

class PrimeClass

{

private Scanner sc = new Scanner(System.in);

public int x;

{

System.out.print(

“Enter the starting value for x: “);

x = sc.nextInt();

}

}

Here are a few other nuggets of information concerning initializers:

If a class contains more than one initializer, the initializers are executed in the order in which they appear in the program.

Initializers are executed before any class constructors.

Although including all initializers at the beginning of the class is common — before any constructors or methods — this ordering isn’t a requirement. Initializers can appear anywhere within ...