Discovering Classes and Objects - Beginning Java 7 - page 100

{
System.out.println(e);
}
}
//...
}
Listing 2-16 ' s JDBCFilterDriver class uses its class initializer to load and in-
stantiate the class that describes Java's JDBC-ODBC Bridge Driver, and to register
a JDBCFilterDriver instance with Java's database driver. Although this listing's
JDBC-orientedcodeisprobablymeaninglesstoyourightnow,thelistingillustratesthe
usefulness of class initializers. (I discuss JDBC in Chapter 9 . )
A class can declare a mix of class initializers and class field initializers, as demon-
strated in Listing 2-17 .
Listing 2-17. Mixing class initializers with class field initializers
class C
{
static
{
System.out.println("class initializer 1");
}
static int counter = 1;
static
{
System.out.println("class initializer 2");
System.out.println("counter = "+counter);
}
}
Listing2-17 declaresaclassnamed C thatspecifiestwoclassinitializersandoneclass
field initializer. When the Java compiler compiles into a classfile a class that declares
atleastoneclassinitializerorclassfieldinitializer,itcreatesaspecial void <clin-
it>() classmethodthatstoresthebytecodeequivalentofallclassinitializersandclass
field initializers in the order they occur (from top to bottom).