常量命名

 

public class f1 {
 public static void main(String[]args)
 {
  final double CM_PER_INCH= 2.53;
  double  paperWidth=8.5;
  double paperHeight=11;
  System.out.println("Paper size in centimeters:"+paperWidth*CM_PER_INCH+"by"+paperHeight*CM_PER_INCH);

 }

}