interface Math
{
double PI=3.1415926;
}class Arithmetic implements Math
{
double roundArea(double radius)
{
return PI*radius*radius;
}
}class Student
{
public static void main(String[] args)
{
Arithmetic a=new Arithmetic();
System.out.println( a.roundArea(3));
//要把上行结果作四舍五入,并保留二位小数,应如何操作?
System.out.println(Math.PI);
System.out.println(Arithmetic.PI);
System.out.println(a.PI);
}
}
{
double PI=3.1415926;
}class Arithmetic implements Math
{
double roundArea(double radius)
{
return PI*radius*radius;
}
}class Student
{
public static void main(String[] args)
{
Arithmetic a=new Arithmetic();
System.out.println( a.roundArea(3));
//要把上行结果作四舍五入,并保留二位小数,应如何操作?
System.out.println(Math.PI);
System.out.println(Arithmetic.PI);
System.out.println(a.PI);
}
}
import java.text.DecimalFormat; DecimalFormat a = new DecimalFormat("0.00");//0.00代表保留两位小数 然后调用a.format()
就可以了
{
double PI=3.1415926;
}class Arithmetic implements MyMath
{
double roundArea(double radius)
{
return PI*radius*radius;
}
}public class Student
{
public static void main(String[] args)
{
Arithmetic a=new Arithmetic();
System.out.println( a.roundArea(3));
//以下简单实现了保留两位小数 和C语言是一样的:)
System.out.printf("%.2f\n", a.roundArea(3));
System.out.println(Math.PI);
System.out.println(Arithmetic.PI);
System.out.println(a.PI);
}
}
建议把Math改名,因为存在java.lang.Math类
您好!感谢你们的提示,但javac Student.java 时出现如下信息:能否再帮我看一下:
cannot resolve symbol
symbol : method printf (java.lang.String,double)
location: class java.io.PrintStream
System.out.printf("%.2f\n", a.roundArea(3)).println();