import java.util.Scanner; public class Circle { private double r; public Circle() { } public Circle(double r) { this.r = r; } public double area() { return Math.PI * r * r; } Circle c = new Circle(); Scanner scanner = new Scanner(System.in); System.out.print("请输入半径:"); double r = scanner.nextDouble(); c.setR(r); System.out.println("圆的面积(使用成员变量r):" + c.area()); 将以上代码中的main 方法定义为: public static void main(String[] args)
时间: 2023-06-26 14:09:20 浏览: 42
public static void main(String[] args) {
Circle c = new Circle();
Scanner scanner = new Scanner(System.in);
System.out.print("请输入半径:");
double r = scanner.nextDouble();
c.r = r;
System.out.println("圆的面积(使用成员变量r):" + c.area());
}
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import java.util.Scanner; public class Circle { private double r; public Circle() { } public Circle(double r) { this.r = r; } public double area() { return Math.PI * r * r; }} 将代码中的main 方法定义为: public static void main(String[] args)
import java.util.Scanner;
public class Circle {
private double r;
public Circle() {
}
public Circle(double r) {
this.r = r;
}
public double area() {
return Math.PI * r * r;
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("请输入圆的半径:");
double r = scanner.nextDouble();
Circle circle = new Circle(r);
System.out.println("圆的面积为:" + circle.area());
}
}
import java.util.Scanner;class Circle { private double radius; public Circle(double radius) throws NegativeRadiusException { if (radius < 0) { throw new NegativeRadiusException("半径不能为负数"); } this.radius = radius; } public double getArea() { return Math.PI * radius * radius; }}class NegativeRadiusException extends Exception { public NegativeRadiusException(String message) { super(message); }}public class Main { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.print("请输入圆的半径:"); double radius = scanner.nextDouble(); try { Circle circle = new Circle(radius); System.out.println("圆的面积为:" + circle.getArea()); } catch (NegativeRadiusException e) { System.out.println("错误信息:" + e.getMessage()); } }}
这段代码是一个Java程序,实现了计算圆的面积的功能。它定义了一个Circle类,其中包含一个构造方法和一个计算圆面积的方法。在构造方法中,会检查传入的半径是否为负数,如果是则会抛出一个自定义的NegativeRadiusException异常。在主函数中,会提示用户输入半径,并且通过try-catch语句来捕获异常并输出错误信息或者计算圆的面积。