java大学实用教程第四章例题.docVIP

例4-1 public class ComputerCircleArea { public static void main (String args[ ]){ double radius; double area; radius=163.16; area=3.14*radius*radius; System.out.printf(半径是%5.3f的圆的面积:\n%5.3f\n,radius,area); } } 例4-2 class Circle{ double radius; double getArea(){ double area=3.14*radius*radius; return area; } } public class Example4_2 { public static void main(String[] args) { // TODO Auto-generated method stub Circle circle; circle=new Circle(); circle.radius=163.16; double area=circle.getArea(); System.out.printf(半径是%5.3f的圆的面积:\n%5.3f\n,circle.radius,area); } } 例4-3 class Lader{ double above,bottom,height; Lader(){} Lader(double a,double b,double h){ above=a; bottom=b; height=h; } public void setAbove(double a){ above=a; } public void setBottom(double b){ bottom=b; } public void setHeight(double h){ height=h; } double computerAera(){ return (above+bottom)*height/2.0; } } public class Example4_1 { public static void main(String[] args) { // TODO Auto-generated method stub double area1=0,area2=0; Lader laderOne,laderTwo; laderOne=new Lader(); laderTwo=new Lader(10,88,20); laderOne.setAbove(16); laderOne.setBottom(26); laderOne.setHeight(100); laderTwo.setAbove(300); laderTwo.setBottom(500); area1=laderOputerAera(); area2=laderTputerAera(); System.out.println(laderOne的above,bottom和height: +laderOne.above+,+laderOne.bottom+,+laderOne.height); System.out.println(laderOne的面积：+area1); System.out.println(laderTwo的above,bottom和height:+laderTwo.above+,+laderTwo.bottom+,+laderTwo.height); System.out.println(laderTwo的面积:+area2); System.exit(0); } } 例4-4 class Lader{ double above,height; static double bottom; void setAbove(double a){ above=a; } void setBottom(double b){ bottom=b; } double getAbove(){ return above; } double getBottom(){ return bottom; } } public class Example4_4 { public static void main(String[