Static block (static block)

From: http://www.cnblogs.com/o-andy-o/archive/2011/12/28/2304959.html

The static block is executed only once when the class is loaded.

Class usestatic {

Static int A = 3;

Static int B;

Static void meth (int x ){

System. out. println ("x =" + x); system. out. println ("A =" + a); system. out. println ("B =" + B );

}

Static {

System. Out. println ("static block initialized .");

B = A * 4;

}

Public static void main (string ARGs []) {

Meth (42 );

}

}

 

Once the usestatic class is loaded, all static statements are run. First, a is set to 3, then the static block is executed (print a message), and finally, B is initialized to a * 4 or 12. Then, call main () and main () to call meth () and pass the value 42 to X. The three println () Statements reference two static variables A and B, and the local variable X. Note: It is invalid to reference any instance variable in a static method. Below isProgramOutput:

Static block initialized.

X = 42

A = 3

B = 12

One step at a time to facilitate your review

 

The static block is executed only once when the class is loaded.

Class usestatic {

Static int A = 3;

Static int B;

Static void meth (int x ){

System. out. println ("x =" + x); system. out. println ("A =" + a); system. out. println ("B =" + B );

}

Static {

System. Out. println ("static block initialized .");

B = A * 4;

}

Public static void main (string ARGs []) {

Meth (42 );

}

}

 

Once the usestatic class is loaded, all static statements are run. First, a is set to 3, then the static block is executed (print a message), and finally, B is initialized to a * 4 or 12. Then, call main () and main () to call meth () and pass the value 42 to X. The three println () Statements reference two static variables A and B, and the local variable X. Note: It is invalid to reference any instance variable in a static method. The output of the program is as follows:

Static block initialized.

X = 42

A = 3

B = 12